1
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Effects of pituitary adenylate cyclase activating polypeptide (PACAP) in corneal epithelial regeneration and signal transduction in rats. Int J Pept Res Ther 2022. [DOI: 10.1007/s10989-022-10405-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AbstractCorneal epithelium responds to insults with a rapid wound healing, which is essential for maintaining vision. The proper balance of apoptotic and proliferation-stimulating pathways is critical for normal regeneration. Pituitary adenylate cyclase activating polypeptide (PACAP) is an important growth factor during the development of the nervous system and exerts cytoprotective effects in injuries. The aim of the present study was to investigate the effects of PACAP on corneal epithelial wound healing in rats and on two important protective signaling molecules, Akt and ERK1/2, both of which have been reported to play important roles during cell survival and regeneration, including corneal wound healing. Wistar rats received PACAP treatment in form of eyedrops, containing 1, 5 and 10 µg PACAP27, immediately and every two hours after corneal abrasion. Corneas were stained with fluorescein dye and further processed for histological staining or Western blot analysis for Akt and ERK1/2 expression. Our results showed that topical PACAP application enhanced corneal wound healing, as the area of injury was significantly less in PACAP-treated groups. Furthermore, both ERK1/2 and Akt signaling was induced upon PACAP administration in both injured and intact corneas. In summary, the present results show that PACAP enhances corneal wound healing in a rat model of corneal abrasion.
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2
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Perlikowska R. Whether short peptides are good candidates for future neuroprotective therapeutics? Peptides 2021; 140:170528. [PMID: 33716091 DOI: 10.1016/j.peptides.2021.170528] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/18/2021] [Accepted: 02/27/2021] [Indexed: 02/07/2023]
Abstract
Neurodegenerative diseases are a broad group of largely debilitating, and ultimately terminal conditions resulting in progressive degeneration of different brain regions. The observed damages are associated with cell death, structural and functional deficits of neurons, or demyelination. The concept of neuroprotection concerns the administration of the agent, which should reverse some of the damage or prevent further adverse changes. A growing body of evidence suggested that among many classes of compounds considered as neuroprotective agents, peptides derived from natural materials or their synthetic analogs are good candidates. They presented a broad spectrum of activities and abilities to act through diverse mechanisms of action. Biologically active peptides have many properties, including antioxidant, antimicrobial, antiinflammatory, and immunomodulatory effects. Peptides with pro-survival and neuroprotective activities, associated with inhibition of oxidative stress, apoptosis, inflammation and are able to improve cell viability or mitochondrial functions, are also promising molecules of particular interest to the pharmaceutical industries. Peptide multiple activities open the way for broad application potential as therapeutic agents or ingredients of health-promoting functional foods. Significantly, synthetic peptides can be remodeled in numerous ways to have desired features, such as increased solubility or biological stability, as well as selectivity towards a specific receptor, and finally better membrane penetration. This review summarized the most common features of major neurodegenerative disorders, their causes, consequences, and reported new neuroprotective drug development approaches. The author focused on the unique perspectives in neuroprotection and provided a concise survey of short peptides proposed as novel therapeutic agents against various neurodegenerative diseases.
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Affiliation(s)
- Renata Perlikowska
- Department of Biomolecular Chemistry, Faculty of Medicine, Medical University of Lodz, 92-215, Lodz, Poland.
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3
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Ruel J, Guitton MJ, Gratias P, Lenoir M, Shen S, Puel JL, Brabet P, Wang J. Endogenous Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) Plays a Protective Effect Against Noise-Induced Hearing Loss. Front Cell Neurosci 2021; 15:658990. [PMID: 33828461 PMCID: PMC8019930 DOI: 10.3389/fncel.2021.658990] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/02/2021] [Indexed: 01/07/2023] Open
Abstract
Pituitary adenylyl cyclase-activating polypeptide (PACAP) is a member of the vasoactive intestinal polypeptide (VIP)-the secretin-glucagon family of neuropeptides. They act through two classes of receptors: PACAP type 1 (PAC1) and type 2 (VPAC1 and VPAC2). Among their pleiotropic effects throughout the body, PACAP functions as neuromodulators and neuroprotectors, rescuing neurons from apoptosis, mostly through the PAC1 receptor. To explore the potential protective effect of endogenous PACAP against Noise-induced hearing loss (NIHL), we used a knockout mouse model lacking PAC1 receptor expression (PACR1−/−) and a transgenic humanized mouse model expressing the human PAC1 receptor (TgHPAC1R). Based on complementary approaches combining electrophysiological, histochemical, and molecular biological evaluations, we show PAC1R expression in spiral ganglion neurons and in cochlear apical cells of the organ of Corti. Wild-type (WT), PAC1R−/−, and TgHPAC1R mice exhibit similar auditory thresholds. For most of the frequencies tested after acute noise damage, however, PAC1R−/− mice showed a larger elevation of the auditory threshold than did their WT counterparts. By contrast, in a transgene copy number-dependent fashion, TgHPAC1R mice showed smaller noise-induced elevations of auditory thresholds compared to their WT counterparts. Together, these findings suggest that PACAP could be a candidate for endogenous protection against noise-induced hearing loss.
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Affiliation(s)
- Jérôme Ruel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France.,Laboratoire de Neurosciences Cognitives, UMR7291 CNRS, Aix-Marseille Université, Marseille, France
| | - Matthieu J Guitton
- CERVO Brain Research Center, Faculty of Medicine, Laval University, Quebec City, QC, Canada
| | - Paul Gratias
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France
| | - Marc Lenoir
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France
| | - Sanbing Shen
- Regenerative Medicine Institute, National University of Ireland (NUI), Galway, Ireland
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France
| | - Philippe Brabet
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France
| | - Jing Wang
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, Montpellier, France
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4
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Meloni BP, Mastaglia FL, Knuckey NW. Cationic Arginine-Rich Peptides (CARPs): A Novel Class of Neuroprotective Agents With a Multimodal Mechanism of Action. Front Neurol 2020; 11:108. [PMID: 32158425 PMCID: PMC7052017 DOI: 10.3389/fneur.2020.00108] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 01/30/2020] [Indexed: 12/17/2022] Open
Abstract
There are virtually no clinically available neuroprotective drugs for the treatment of acute and chronic neurological disorders, hence there is an urgent need for the development of new neuroprotective molecules. Cationic arginine-rich peptides (CARPs) are an expanding and relatively novel class of compounds, which possess intrinsic neuroprotective properties. Intriguingly, CARPs possess a combination of biological properties unprecedented for a neuroprotective agent including the ability to traverse cell membranes and enter the CNS, antagonize calcium influx, target mitochondria, stabilize proteins, inhibit proteolytic enzymes, induce pro-survival signaling, scavenge toxic molecules, and reduce oxidative stress as well as, having a range of anti-inflammatory, analgesic, anti-microbial, and anti-cancer actions. CARPs have also been used as carrier molecules for the delivery of other putative neuroprotective agents across the blood-brain barrier and blood-spinal cord barrier. However, there is increasing evidence that the neuroprotective efficacy of many, if not all these other agents delivered using a cationic arginine-rich cell-penetrating peptide (CCPPs) carrier (e.g., TAT) may actually be mediated largely by the properties of the carrier molecule, with overall efficacy further enhanced according to the amino acid composition of the cargo peptide, in particular its arginine content. Therefore, in reviewing the neuroprotective mechanisms of action of CARPs we also consider studies using CCPPs fused to a putative neuroprotective peptide. We review the history of CARPs in neuroprotection and discuss in detail the intrinsic biological properties that may contribute to their cytoprotective effects and their usefulness as a broad-acting class of neuroprotective drugs.
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Affiliation(s)
- Bruno P Meloni
- Department of Neurosurgery, QEII Medical Centre, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.,Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia.,Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA, Australia
| | - Frank L Mastaglia
- Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia.,Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA, Australia
| | - Neville W Knuckey
- Department of Neurosurgery, QEII Medical Centre, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.,Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia.,Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA, Australia
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5
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Atlasz T, Werling D, Song S, Szabo E, Vaczy A, Kovari P, Tamas A, Reglodi D, Yu R. Retinoprotective Effects of TAT-Bound Vasoactive Intestinal Peptide and Pituitary Adenylate Cyclase Activating Polypeptide. J Mol Neurosci 2019. [PMID: 30542799 DOI: 10.1007/s12031-018-1229-5/figures/7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) belong to the same peptide family and exert a variety of biological functions. Both PACAP and VIP have protective effects in several tissues. While PACAP is known to be a stronger retinoprotective peptide, VIP has very potent anti-inflammatory effects. The need for a non-invasive therapeutic approach has emerged and PACAP has been shown to be retinoprotective when administered in the form of eye drops as well. The cell penetrating peptide TAT is composed of 11 amino acids and tagging of TAT at the C-terminus of neuropeptides PACAP/VIP can enhance the traversing ability of the peptides through the biological barriers. We hypothesized that TAT-bound PACAP and VIP could be more effective in exerting retinoprotective effects when given in eye drops, by increasing the traversing efficacy and enhancing the activation of the PAC1 receptor. Rats were subjected to bilateral carotid artery occlusion (BCCAO), and retinas were processed for histological analysis 14 days later. The efficiency of the TAT-bound peptides to reach the retina was assessed as well as their cAMP increasing ability. Our present study provides evidence, for the first time, that topically administered PACAP and VIP derivatives (PACAP-TAT and VIP-TAT) attenuate ischemic retinal degeneration via the PAC1 receptor presumably due to a multifactorial protective mechanism.
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Affiliation(s)
- Tamas Atlasz
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary.
- Department of Sportbiology, University of Pecs, Pecs, Hungary.
- Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary.
| | - D Werling
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - S Song
- Institute of Biomedicine, Jinan University, Guangzhou, China
| | - E Szabo
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - A Vaczy
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - P Kovari
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - A Tamas
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - D Reglodi
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - Rongjie Yu
- Institute of Biomedicine, Jinan University, Guangzhou, China.
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6
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Atlasz T, Werling D, Song S, Szabo E, Vaczy A, Kovari P, Tamas A, Reglodi D, Yu R. Retinoprotective Effects of TAT-Bound Vasoactive Intestinal Peptide and Pituitary Adenylate Cyclase Activating Polypeptide. J Mol Neurosci 2018; 68:397-407. [PMID: 30542799 PMCID: PMC6581923 DOI: 10.1007/s12031-018-1229-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/21/2018] [Indexed: 12/19/2022]
Abstract
Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) belong to the same peptide family and exert a variety of biological functions. Both PACAP and VIP have protective effects in several tissues. While PACAP is known to be a stronger retinoprotective peptide, VIP has very potent anti-inflammatory effects. The need for a non-invasive therapeutic approach has emerged and PACAP has been shown to be retinoprotective when administered in the form of eye drops as well. The cell penetrating peptide TAT is composed of 11 amino acids and tagging of TAT at the C-terminus of neuropeptides PACAP/VIP can enhance the traversing ability of the peptides through the biological barriers. We hypothesized that TAT-bound PACAP and VIP could be more effective in exerting retinoprotective effects when given in eye drops, by increasing the traversing efficacy and enhancing the activation of the PAC1 receptor. Rats were subjected to bilateral carotid artery occlusion (BCCAO), and retinas were processed for histological analysis 14 days later. The efficiency of the TAT-bound peptides to reach the retina was assessed as well as their cAMP increasing ability. Our present study provides evidence, for the first time, that topically administered PACAP and VIP derivatives (PACAP-TAT and VIP-TAT) attenuate ischemic retinal degeneration via the PAC1 receptor presumably due to a multifactorial protective mechanism.
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Affiliation(s)
- Tamas Atlasz
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary. .,Department of Sportbiology, University of Pecs, Pecs, Hungary. .,Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary.
| | - D Werling
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - S Song
- Institute of Biomedicine, Jinan University, Guangzhou, China
| | - E Szabo
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - A Vaczy
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - P Kovari
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - A Tamas
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - D Reglodi
- Department of Anatomy, Medical School, MTA-PTE PACAP Research Group, University of Pecs, Pecs, Hungary
| | - Rongjie Yu
- Institute of Biomedicine, Jinan University, Guangzhou, China.
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7
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Ye D, Yang Y, Lu X, Xu Y, Shi Y, Chen H, Huang J. Spatiotemporal Expression Changes of PACAP and Its Receptors in Retinal Ganglion Cells After Optic Nerve Crush. J Mol Neurosci 2018; 68:465-474. [PMID: 30415445 DOI: 10.1007/s12031-018-1203-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 10/30/2018] [Indexed: 12/14/2022]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) has been demonstrated to play a crucial part in protecting retinal ganglion cells (RGCs) from apoptosis in various retinal injury animal models. PACAP has two basic groups of receptors: PACAP receptor type 1 (PAC1R) and vasoactive intestinal polypeptide/PACAP receptors (VPAC1R and VPAC2R). However, few studies illustrated the spatial and temporal expression changes of endogenous PACAP and its receptors in a rodent optic nerve crush (ONC) model. In this study, a significant upregulation of PACAP and PAC1R in the retina after ONC was observed in both protein and RNA levels. The peak level of PACAP and PAC1R expression could be found on the fifth day following ONC. In addition, immunofluorescent labeling indicated that PACAP and PAC1R were localized mainly in RGCs. On the contrary, VPAC1R and VPAC2R were hardly detected in the retina. Collectively, the spatiotemporal expression of PACAP and its high-affinity receptor PAC1R were remarkably changed after ONC, and mainly expressed in the ganglion cell layer of the retina. This suggested that the upregulation of PACAP and PAC1R may play a vital role in RGC death after ONC.
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Affiliation(s)
- Dan Ye
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlienan Road, Guangzhou, 510060, China
| | - Yao Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlienan Road, Guangzhou, 510060, China
| | - Xi Lu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlienan Road, Guangzhou, 510060, China
| | - Yue Xu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlienan Road, Guangzhou, 510060, China
| | - Yuxun Shi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlienan Road, Guangzhou, 510060, China
| | - Hailiu Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlienan Road, Guangzhou, 510060, China
| | - Jingjing Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlienan Road, Guangzhou, 510060, China.
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8
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Werling D, Banks WA, Salameh TS, Kvarik T, Kovacs LA, Vaczy A, Szabo E, Mayer F, Varga R, Tamas A, Toth G, Biro Z, Atlasz T, Reglodi D. Passage through the Ocular Barriers and Beneficial Effects in Retinal Ischemia of Topical Application of PACAP1-38 in Rodents. Int J Mol Sci 2017; 18:ijms18030675. [PMID: 28335564 PMCID: PMC5372685 DOI: 10.3390/ijms18030675] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/08/2017] [Accepted: 03/12/2017] [Indexed: 01/14/2023] Open
Abstract
The neuropeptide pituitary adenylate cyclase activating polypeptide (PACAP) has two active forms, PACAP1-27 and PACAP1-38. Among the well-established actions are PACAP’s neurotrophic and neuroprotective effects, which have also been proven in models of different retinopathies. The route of delivery is usually intravitreal in studies proving PACAP’s retinoprotective effects. Recently, we have shown that PACAP1-27 delivered as eye drops in benzalkonium-chloride was able to cross the ocular barriers and exert retinoprotection in ischemia. Since PACAP1-38 is the dominant form of the naturally occurring PACAP, our aim was to investigate whether the longer form is also able to cross the barriers and exert protective effects in permanent bilateral common carotid artery occlusion (BCCAO), a model of retinal hypoperfusion. Our results show that radioactive PACAP1-38 eye drops could effectively pass through the ocular barriers to reach the retina. Routine histological analysis and immunohistochemical evaluation of the Müller glial cells revealed that PACAP1-38 exerted retinoprotective effects. PACAP1-38 attenuated the damage caused by hypoperfusion, apparent in almost all retinal layers, and it decreased the glial cell overactivation. Overall, our results confirm that PACAP1-38 given in the form of eye drops is a novel protective therapeutic approach to treat retinal diseases.
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Affiliation(s)
- Dora Werling
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
- Department of Ophthalmology, University of Pecs, Pecs 7624, Hungary.
| | - William A Banks
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA.
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98122, USA.
| | - Therese S Salameh
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA.
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98122, USA.
| | - Timea Kvarik
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
| | - Laszlo Akos Kovacs
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
| | - Alexandra Vaczy
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
| | - Edina Szabo
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
| | - Flora Mayer
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
| | - Rita Varga
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
| | - Andrea Tamas
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
| | - Gabor Toth
- Department of Medical Chemistry, University of Szeged, Szeged 6720, Hungary.
| | - Zsolt Biro
- Department of Ophthalmology, University of Pecs, Pecs 7624, Hungary.
| | - Tamas Atlasz
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
- Department of Sportbiology, University of Pecs, Pecs 7624, Hungary.
- Janos Szentagothai Research Center, University of Pecs, Pecs 7624, Hungary.
| | - Dora Reglodi
- Department of Anatomy, University of Pecs, Medical School, Pecs 7624, Hungary.
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9
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Shioda S, Takenoya F, Wada N, Hirabayashi T, Seki T, Nakamachi T. Pleiotropic and retinoprotective functions of PACAP. Anat Sci Int 2016; 91:313-24. [PMID: 27324639 DOI: 10.1007/s12565-016-0351-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 06/08/2016] [Indexed: 10/21/2022]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a 27- or 38-amino acid neuropeptide, which belongs to the vasoactive intestinal polypeptide/glucagon/secretin family. PACAP and its three receptor subtypes are expressed in neural tissues of the eye, including the retina, cornea and lacrimal gland, and PACAP is known to exert pleiotropic effects throughout the central nervous system. This review provides an overview of current knowledge regarding the cell protective effects, mechanisms of action and therapeutic potential of PACAP in response to several types of eye injury.
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Affiliation(s)
- Seiji Shioda
- Global Research Center for Innovative Life Science, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.
| | - Fumiko Takenoya
- Global Research Center for Innovative Life Science, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Nobuhiro Wada
- Global Research Center for Innovative Life Science, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Takahiro Hirabayashi
- Global Research Center for Innovative Life Science, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Tamotsu Seki
- Department of Anatomy and Ophthalmology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Tomoya Nakamachi
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan
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10
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Bhandare AM, Kapoor K, Farnham MM, Pilowsky PM. Microglia PACAP and glutamate: Friends or foes in seizure-induced autonomic dysfunction and SUDEP? Respir Physiol Neurobiol 2016; 226:39-50. [DOI: 10.1016/j.resp.2016.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 01/18/2016] [Accepted: 01/21/2016] [Indexed: 12/18/2022]
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11
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Lakk M, Denes V, Gabriel R. Pituitary Adenylate Cyclase-Activating Polypeptide Receptors Signal via Phospholipase C Pathway to Block Apoptosis in Newborn Rat Retina. Neurochem Res 2015; 40:1402-9. [PMID: 25975365 DOI: 10.1007/s11064-015-1607-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 04/03/2015] [Accepted: 05/07/2015] [Indexed: 12/22/2022]
Abstract
Glutamate induced cell death mechanisms gained considerable attention lately as excessive release of extracellular glutamate was reported to cause neurodegeneration in brain areas including the retina. Conversely, pituitary adenylate cyclase-activating polypeptide (PACAP) was shown to provide neuroprotection through anti-apoptotic effects in the glutamate-model and also in other degeneration assays. Although PACAP is known to orchestrate complex intracellular signaling primarily through cAMP production, the mechanism that mediates the anti-apoptotic effect in glutamate excitotoxicity remains to be clarified. To study this mechanism we induced retinal neurodegeneration in newborn Wistar rats by subcutaneous monosodium-glutamate injection. 100 pmol PACAP and enzyme inhibitors were administered intravitreally. Levels of caspase 3, 9, and phospho-protein kinase A were assessed by Western blots. Changes in cAMP levels were detected employing a competitive immunoassay. We found that cAMP blockade by an adenylyl-cyclase inhibitor (2',4'-dideoxy-adenosine) did not abrogate the neuroprotective effect of PACAP1-38. We show that following intravitreal PACAP1-38 treatment cAMP was unaltered, consistent with the inhibitor results and phospho-protein kinase A, an effector of the cAMP pathway was also unaffected. On the other hand, blockade of the alternative phosphatidylcholine-specific PLC pathway using an inhibitor (D609CAS) abrogated the neuroprotective effects of PACAP1-38. Our results highlight PACAP1-38 ability in protecting retinal cells against apoptosis through diverse signaling cascades. It seems that at picomolar concentrations, PACAP does not trigger cAMP production, but nonetheless, exerts a significant anti-apoptotic effect through PLC activation. In conclusion, PACAP1-38 may signal via both AC and PLC activation producing the same protective outcome.
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Affiliation(s)
- Monika Lakk
- Department of Experimental Zoology and Neurobiology, University of Pécs, 6 Ifjúság Street, 7601, Pécs, Hungary
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12
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Lee EH, Seo SR. Neuroprotective roles of pituitary adenylate cyclase-activating polypeptide in neurodegenerative diseases. BMB Rep 2015; 47:369-75. [PMID: 24856828 PMCID: PMC4163857 DOI: 10.5483/bmbrep.2014.47.7.086] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Indexed: 12/04/2022] Open
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic bioactive peptide that was first isolated from an ovine hypothalamus in 1989. PACAP belongs to the secretin/glucagon/vasoactive intestinal polypeptide (VIP) superfamily. PACAP is widely distributed in the central and peripheral nervous systems and acts as a neurotransmitter, neuromodulator, and neurotrophic factor via three major receptors (PAC1, VPAC1, and VPAC2). Recent studies have shown a neuroprotective role of PACAP using in vitro and in vivo models. In this review, we briefly summarize the current findings on the neurotrophic and neuroprotective effects of PACAP in different brain injury models, such as cerebral ischemia, Parkinson’s disease (PD), and Alzheimer’s disease (AD). This review will provide information for the future development of therapeutic strategies in treatment of these neurodegenerative diseases. [BMB Reports 2014; 47(7): 369-375]
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Affiliation(s)
- Eun Hye Lee
- Department of Molecular Bioscience, College of Biomedical Science, and Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701, Korea
| | - Su Ryeon Seo
- Department of Molecular Bioscience, College of Biomedical Science, and Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701, Korea
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Ko JA, Hirata J, Yamane K, Sonoda KH, Kiuchi Y. Up-regulation of semaphorin 4A expression in human retinal pigment epithelial cells by PACAP released from cocultured neural cells. Cell Biochem Funct 2014; 33:29-36. [PMID: 25515530 DOI: 10.1002/cbf.3082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/04/2014] [Accepted: 11/05/2014] [Indexed: 01/01/2023]
Abstract
Development and homeostasis of multicellular organisms require interactions between neighbouring cells. We recently established an in vitro model of cell-cell interaction based on a collagen vitrigel membrane. We have now examined the role of neural cells in retinal homeostasis by coculture of human retinal pigment epithelial (RPE) cells and neural cells on opposite sides of such a membrane. The neural cells (differentiated PC12 cells) induced up-regulation of semaphorin 4A (Sema4A), a member of the semaphorin family of neural guidance proteins, in RPE (ARPE19) cells. This effect of the neural cells was mimicked by the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) and was abolished by the PACAP antagonist PACAP(6-38). Coculture with neural cells or stimulation with PACAP also induced the phosphorylation of extracellular-signal-regulated kinase in ARPE19 cells, and this effect of the neural cells was inhibited by PACAP(6-38). Finally, among various cytokines examined, only the amount of interleukin-6 released by cocultures of ARPE19 and neural cells differed from that released by ARPE19 cells cultured alone. Interleukin-6 was not detected in culture supernatants of neural cells, and the reduction in the amount of interleukin-6 released by the cocultures compared with that released by ARPE19 cells alone was prevented by PACAP(6-38). Our findings suggest that PACAP released from retinal neural cells (photoreceptors or optic nerve cells) may regulate Sema4A expression in RPE cells and thereby contribute to the maintenance of retinal structure and function. Development and homeostasis of multicellular organisms require interactions between neighbouring cells. With the use of a coculture system based on a collagen vitrigel membrane, we have now shown that neural cells induce up-regulation of the neural guidance protein Sema4A in RPE cells. This effect of neural cells appears to be mediated by the neuropeptide PACAP. PACAP released from retinal neural cells (photoreceptors or optic nerve cells) may thus regulate Sema4A expression in RPE cells and thereby contribute to the maintenance of retinal structure and function.
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Affiliation(s)
- Ji-Ae Ko
- Department of Ophthalmology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima City, Hiroshima, Japan
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Investigation of PACAP Fragments and Related Peptides in Chronic Retinal Hypoperfusion. J Ophthalmol 2014; 2014:563812. [PMID: 24900914 PMCID: PMC4036611 DOI: 10.1155/2014/563812] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 03/24/2014] [Indexed: 12/05/2022] Open
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) has neuroprotective effects in different neuronal and retinal injuries. Retinal ischemia can be effectively modelled by permanent bilateral common carotid artery occlusion (BCCAO), which causes chronic hypoperfusion-induced degeneration in the entire rat retina. The retinoprotective effect of PACAP 1-38 and VIP is well-established in ischemic retinopathy. However, little is known about the effects of related peptides and PACAP fragments in ischemic retinopathy. The aim of the present study was to investigate the potential retinoprotective effects of different PACAP fragments (PACAP 4-13, 4-22, 6-10, 6-15, 11-15, and 20-31) and related peptides (secretin, glucagon) in BCCAO-induced ischemic retinopathy. Wistar rats (3-4 months old) were used in the experiment. After performing BCCAO, the right eyes of the animals were treated with PACAP fragments or related peptides intravitreal (100 pM), while the left eyes were injected with saline serving as control eyes. Sham-operated (without BCCAO) rats received the same treatment. Routine histology was performed 2 weeks after the surgery; cells were counted and the thickness of retinal layers was compared. Our results revealed significant neuroprotection by PACAP 1-38 but did not reveal retinoprotective effect of the PACAP fragments or related peptides. These results suggest that PACAP 1-38 has the greatest efficacy in ischemic retinopathy.
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D'Alessandro A, Cervia D, Catalani E, Gevi F, Zolla L, Casini G. Protective effects of the neuropeptides PACAP, substance P and the somatostatin analogue octreotide in retinal ischemia: a metabolomic analysis. MOLECULAR BIOSYSTEMS 2014; 10:1290-304. [PMID: 24514073 DOI: 10.1039/c3mb70362b] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ischemia is a primary cause of neuronal death in retinal diseases and the somatostatin subtype receptor 2 agonist octreotide (OCT) is known to decrease ischemia-induced retinal cell death. Using a recently optimized ex vivo mouse model of retinal ischemia, we tested the anti-ischemic potential of two additional neuropeptides, pituitary adenylate cyclase activating peptide (PACAP) and substance P (SP), and monitored the major changes occurring at the metabolic level. Metabolomics analyses were performed via fast HPLC online using a microTOF-Q MS instrument, a workflow that is increasingly becoming the gold standard in the field of metabolomics. The metabolomic approach allowed detection of the most significant alterations induced in the retina by ischemia and of the significance of the protective effects exerted by OCT, PACAP or SP. All treatments were shown to reduce ischemia-induced cell death, vascular endothelial growth factor over-expression and glutamate release. The metabolomic analysis showed that OCT and, to a lesser extent, also PACAP or SP, were able to counteract the ischemia-induced oxidative stress and to promote, with various efficacies, (i) decreased accumulation of glutamate and normalization of glutathione homeostasis; (ii) reduced build-up of α-ketoglutarate, which might serve as a substrate for the enhanced biosynthesis of glutamate in response to ischemia; (iii) reduced accumulation of peroxidized lipids and inflammatory mediators; (iv) the normalization of glycolytic fluxes and thus preventing the over-accumulation of lactate or either promoting the down-regulation of the glyoxalate anti-oxidant system; (v) a reduced metabolic shift from glycolysis towards the PPP or either a blockade at the non-oxidative phase of the PPP; and (vi) tuning down of purine metabolism. In addition, OCT seemed to stimulate nitric oxide production. None of the treatments was able to restore ATP production, although ATP reservoirs were partly replenished by OCT, PACAP or SP. These data indicate that, in addition to that of somatostatin, peptidergic systems such as those of PACAP and SP deserve attention in view of peptide-based therapies to treat ischemic retinal disorders.
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Affiliation(s)
- Angelo D'Alessandro
- Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, L.go dell'Università snc, I-01100 Viterbo, Italy.
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STC1 induction by PACAP is mediated through cAMP and ERK1/2 but not PKA in cultured cortical neurons. J Mol Neurosci 2013; 46:75-87. [PMID: 21975601 DOI: 10.1007/s12031-011-9653-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 09/15/2011] [Indexed: 10/17/2022]
Abstract
The neuroprotective actions of PACAP (pituitary adenylate cyclase-activating polypeptide) in vitro and in vivo suggest that activation of its cognate G protein coupled receptor PAC1 or downstream signaling molecules,and thus activation of PACAP target genes, could be of therapeutic benefit. Here, we show that cultured rat cortical neurons predominantly expressed the PAC1hop and null variants. PACAP receptor activation resulted in the elevation of the two second messengers cAMP and Ca(2+) and expression of the putative neuroprotectant stanniocalcin 1(STC1). PACAP signaling to the STC1 gene proceeded through the extracellular signal-regulated kinases 1 and 2(ERK1/2), but not through the cAMP-dependent protein kinase (PKA), and was mimicked by the adenylate cyclase activator forskolin. PACAP- and forskolin-mediated activation of ERK1/2 occurred through cAMP, but not PKA.These results suggest that STC1 gene induction proceeds through cAMP and ERK1/2, independently of PKA, the canonical cAMP effector. In contrast, PACAP signaling to the BDNF gene proceeded through PKA, suggesting that two different neuroprotective cAMP pathways co-exist in differentiated cortical neurons. The selective activation of a potentially neuroprotective cAMP-dependent pathway different from the canonical cAMP pathway used in many physiological processes, such as memory storage, has implications for pharmacological activation of neuroprotection in vivo.
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Scuderi S, D'Amico AG, Castorina A, Imbesi R, Carnazza ML, D'Agata V. Ameliorative effect of PACAP and VIP against increased permeability in a model of outer blood retinal barrier dysfunction. Peptides 2013; 39:119-24. [PMID: 23220033 DOI: 10.1016/j.peptides.2012.11.015] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 11/22/2012] [Accepted: 11/26/2012] [Indexed: 11/15/2022]
Abstract
Breakdown of outer blood retinal barrier (BRB) due to the disruption of tight junctions (TJs) is one of the main factors accounting for diabetic macular edema (DME), a major complication of diabetic retinopathy. Previously it has been shown that PACAP and VIP are protective against several types of retinal injuries. However, their involvement in the maintenance of outer BRB function during DME remains uncovered. Here, using an in vitro model of DME, we explored the effects of both PACAP and VIP. Human retinal pigment epithelial cells (ARPE19) were cultured for 26 days either in normal glucose (5.5 mM, NG) or in high glucose (25 mM, HG). In addition, to mimic the inflammatory aspect of the diabetic milieu, cells were also treated with IL-1β (NG+IL-1β and HG+IL-1β). Effects of PACAP or VIP on cells permeability were evaluated by measuring both apical-to-basolateral movements of fluorescein isothyocyanate (FITC) dextran and transepithelial electrical resistance (TEER). Expression of TJ-related proteins was evaluated by immunoblot. Results demonstrated that NG+IL-1β and, to a greater extent, HG+IL-1β significantly increased FITC-dextran diffusion, paralleled by decreased TEER. PACAP or VIP reversed both of these effects. Furthermore, HG+IL-1β-induced reduction of claudin-1 and ZO-1 expression was reversed by PACAP and VIP. Occludin expression was not affected in any of the conditions tested. Altogether, these finding show that both peptides counteract HG+IL-1β-induced damage in ARPE19 cells, suggesting that they might be relevant to the maintenance of outer BRB function in DME.
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Affiliation(s)
- Soraya Scuderi
- Department of Bio-Medical Sciences, University of Catania, Catania, Italy
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Giunta S, Castorina A, Bucolo C, Magro G, Drago F, D'Agata V. Early changes in pituitary adenylate cyclase-activating peptide, vasoactive intestinal peptide and related receptors expression in retina of streptozotocin-induced diabetic rats. Peptides 2012; 37:32-9. [PMID: 22721946 DOI: 10.1016/j.peptides.2012.06.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 06/11/2012] [Accepted: 06/11/2012] [Indexed: 11/26/2022]
Abstract
The retinal expression and distribution of pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) and their receptors was investigated in early streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in rats by STZ injection (60 mg/kg i.p.). PACAP, VIP and their receptors in nondiabetic control and diabetic retinas were assayed by quantitative real-time PCR and Western blot 1 and 3 weeks after STZ injection. Effects of intravitreal treatment with PACAP38 on the expression of the two apoptotic-related genes Bcl-2 and p53 were also evaluated. PACAP and VIP, as well as VPAC1 and VPAC2 receptors, but not PAC1 mRNA levels, were transiently induced in retinas 1 week following STZ. These findings were confirmed by immunoblot analyses. Three weeks after the induction of diabetes, significant decreases in the expression of peptides and their receptors were observed, Bcl-2 expression decreased and p53 expression increased. Intravitreal injection of PACAP38 restored STZ-induced changes in retinal Bcl-2 and p53 expression to nondiabetic levels. The initial upregulation of PACAP, VIP and related receptors and the subsequent downregulation in retina of diabetic rats along with the protective effects of PACAP38 treatment, suggest a role for both peptides in the pathogenesis of diabetic retinopathy.
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MESH Headings
- Animals
- Base Sequence
- Blood Glucose
- DNA Primers/genetics
- Diabetes Mellitus, Experimental/blood
- Diabetes Mellitus, Experimental/metabolism
- Gene Expression/drug effects
- Intravitreal Injections
- Male
- Pituitary Adenylate Cyclase-Activating Polypeptide/administration & dosage
- Pituitary Adenylate Cyclase-Activating Polypeptide/metabolism
- Pituitary Adenylate Cyclase-Activating Polypeptide/pharmacology
- Proto-Oncogene Proteins c-bcl-2/genetics
- Proto-Oncogene Proteins c-bcl-2/metabolism
- Rats, Sprague-Dawley
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I/genetics
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I/metabolism
- Receptors, Vasoactive Intestinal Peptide, Type II/genetics
- Receptors, Vasoactive Intestinal Peptide, Type II/metabolism
- Receptors, Vasoactive Intestinal Polypeptide, Type I/genetics
- Receptors, Vasoactive Intestinal Polypeptide, Type I/metabolism
- Retina/metabolism
- Streptozocin
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Vasoactive Intestinal Peptide/metabolism
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Protective Effects of Vasoactive Intestinal Peptide (VIP) in Ischemic Retinal Degeneration. J Mol Neurosci 2012; 48:501-7. [DOI: 10.1007/s12031-012-9774-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/09/2012] [Indexed: 01/19/2023]
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Nakamachi T, Matkovits A, Seki T, Shioda S. Distribution and protective function of pituitary adenylate cyclase-activating polypeptide in the retina. Front Endocrinol (Lausanne) 2012; 3:145. [PMID: 23189073 PMCID: PMC3504973 DOI: 10.3389/fendo.2012.00145] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP), which is found in 27- or 38-amino acid forms, belongs to the VIP/glucagon/secretin family. PACAP and its three receptor subtypes are expressed in neural tissues, with PACAP known to exert a protective effect against several types of neural damage. The retina is considered to be part of the central nervous system, and retinopathy is a common cause of profound and intractable loss of vision. This review will examine the expression and morphological distribution of PACAP and its receptors in the retina, and will summarize the current state of knowledge regarding the protective effect of PACAP against different kinds of retinal damage, such as that identified in association with diabetes, ultraviolet light, hypoxia, optic nerve transection, and toxins. This article will also address PACAP-mediated protective pathways involving retinal glial cells.
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Affiliation(s)
- Tomoya Nakamachi
- Department of Anatomy, Showa University School of MedicineTokyo, Japan
- Center for Biotechnology, Showa UniversityTokyo, Japan
| | - Attila Matkovits
- Department of Anatomy, Showa University School of MedicineTokyo, Japan
- Center for Biotechnology, Showa UniversityTokyo, Japan
| | - Tamotsu Seki
- Department of Anatomy, Showa University School of MedicineTokyo, Japan
- Center for Biotechnology, Showa UniversityTokyo, Japan
| | - Seiji Shioda
- Department of Anatomy, Showa University School of MedicineTokyo, Japan
- *Correspondence: Seiji Shioda, Department of Anatomy, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan. e-mail:
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Teuchner B, Dimmer A, Humpel C, Amberger A, Fischer-Colbrie R, Nemeth J, Waschek JA, Kieselbach G, Kralinger M, Schmid E, Bechrakis N, Troger J. VIP, PACAP-38, BDNF and ADNP in NMDA-induced excitotoxicity in the rat retina. Acta Ophthalmol 2011; 89:670-5. [PMID: 20064115 DOI: 10.1111/j.1755-3768.2009.01828.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PURPOSE To evaluate the effect of intravitreal injection of N-methyl-D-aspartate (NMDA) on brain-derived neurotrophic factor (BDNF), pituitary adenylate cyclase-activating peptide-38 (PACAP-38), vasoactive intestinal peptide (VIP) and the VIP-associated glial protein activity-dependent neuroprotective protein (ADNP) in the rat retina. These elements have well-documented neuroprotective properties and may thus be integrated in endogenous neuroprotective mechanisms in the retina which break down in NMDA excitotoxicity. METHODS A volume of 2 μl of 100 nmol NMDA was intravitreally injected into one eye of rats, the untreated eye served as a control. Time-dependent effects of NMDA on VIP, PACAP-38 and BDNF were detected by radioimmunoassay and ELISA, and the effect on the expression of VIP, PACAP-38 and ADNP was evaluated by quantitative RT-PCR 20 days after NMDA injection. Topical flunarizine served to find out whether the effect of NMDA is counteracted. RESULTS Compared to PACAP-38, VIP levels significantly decreased on days 1, 7, 14, 28 and 56 after NMDA injection indicating that VIPergic cells are more vulnerable than PACAP-38-expressing cells. The expression of VIP and ADNP but not of PACAP-38 was found to be reduced, and application of topical flunarizine counteracted the decrease of VIP. BDNF levels significantly increased after days 1 and 3. CONCLUSION The early upregulation of BDNF seems to act neuroprotectively and leads to a delay of ganglion cell loss. Although there is no direct evidence, the decrease of VIP and ADNP - the consequence of the presence of NMDA receptors on these peptide-expressing cells - might contribute to the breakdown of endogenous neuroprotective mechanisms given that the decrease of the VIP-related ADNP runs in parallel with the decrease of VIP. Activating and maintaining these mechanisms must be the primary aim in the therapy of diseases with retinal neuronal degeneration.
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Affiliation(s)
- Barbara Teuchner
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria
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Atlasz T, Szabadfi K, Kiss P, Racz B, Gallyas F, Tamas A, Gaal V, Marton Z, Gabriel R, Reglodi D. Pituitary adenylate cyclase activating polypeptide in the retina: focus on the retinoprotective effects. Ann N Y Acad Sci 2010; 1200:128-39. [PMID: 20633141 DOI: 10.1111/j.1749-6632.2010.05512.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is a neurotrophic and neuroprotective peptide that has been shown to exert protective effects against different neuronal injuries, such as traumatic brain and spinal cord injury, models of neurodegenerative diseases, and cerebral ischemia. PACAP and its receptors are present in the retina. In this study, we summarize the current knowledge on retinal PACAP with focus on the retinoprotective effects. Results of histological, immunohistochemical, and molecular biological analysis are reviewed. In vitro, PACAP shows protection against glutamate, thapsigargin, anisomycin, and anoxia. In vivo, the protective effects of intravitreal PACAP treatment have been shown in the following models of retinal degeneration in rats: excitotoxic injury induced by glutamate and kainate, ischemic injury, degeneration caused by UV-A light, optic nerve transection, and streptozotocin-induced diabetic retinopathy. Studying the molecular mechanism has revealed that PACAP acts by activating antiapoptotic and inhibiting proapoptotic signaling pathways in the retina in vivo. These studies strongly suggest that PACAP is an excellent candidate retinoprotective agent that could be a potential therapeutic substance in various retinal diseases.
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Affiliation(s)
- T Atlasz
- Department of Sportbiology, University of Pecs, Pecs, Hungary
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23
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Mester L, Kovacs K, Racz B, Solti I, Atlasz T, Szabadfi K, Tamas A, Reglodi D. Pituitary Adenylate Cyclase-Activating Polypeptide is Protective Against Oxidative Stress in Human Retinal Pigment Epithelial Cells. J Mol Neurosci 2010; 43:35-43. [DOI: 10.1007/s12031-010-9427-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 07/07/2010] [Indexed: 12/27/2022]
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Seki T, Itoh H, Nakamachi T, Endo K, Wada Y, Nakamura K, Shioda S. Suppression of rat retinal ganglion cell death by PACAP following transient ischemia induced by high intraocular pressure. J Mol Neurosci 2010; 43:30-4. [PMID: 20585899 DOI: 10.1007/s12031-010-9410-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 06/11/2010] [Indexed: 01/26/2023]
Abstract
Glaucoma is a neurodegenerative disease in which increasing intraocular pressure leads to the progressive loss of retinal ganglion cells (RGCs) and blindness. Here, we report a neuroprotective effect of pituitary adenylate cyclase-activating polypeptide (PACAP) against RGC loss induced by high intraocular pressure in the rat. Vehicle or PACAP (1 fM to 1,000 pM) solution was injected into the vitreous body once after induction of a high intraocular pressure (110 mmHg). Seven days later, the number of viable RGCs was reduced to 45% of that in the intact control. However, PACAP treatment significantly reduced this RGC death in a bimodal manner, with peaks at 10 fM and 10-100 pM. The cAMP antagonist Rp-cAMP significantly blocked the neuroprotective effect of PACAP at both high and low doses, whereas the MAP kinase inhibitor PD-98059 only prevented the effect of the low dose of PACAP. These findings suggest that PACAP has bimodal effects in the neuroprotection of RGCs against ischemia and that these effects are mediated via different signaling pathways.
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Affiliation(s)
- Tamotsu Seki
- Department of Anatomy, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
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Atlasz T, Szabadfi K, Kiss P, Marton Z, Griecs M, Hamza L, Gaal V, Biro Z, Tamas A, Hild G, Nyitrai M, Toth G, Reglodi D, Gabriel R. Effects of PACAP in UV-A radiation-induced retinal degeneration models in rats. J Mol Neurosci 2010; 43:51-7. [PMID: 20521124 DOI: 10.1007/s12031-010-9392-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Accepted: 05/11/2010] [Indexed: 11/26/2022]
Abstract
The retina is constantly exposed to ultraviolet (UV) light with different wavelengths, which may lead to chronic UV-induced retinal injury. In our previous studies, we have shown the protective effects of pituitary adenylate cyclase activating polypeptide (PACAP) in toxic and ischemic retinal injuries. The aim of the present study was to investigate the effects of PACAP in UV-A-induced retinal lesion. We used diffuse UV-A radiation (315-400 nm) to induce acute retinal damage over a short period of exposure. Using standard histological (morphological and morphometrical) analysis, we assessed the actions of intravitreal PACAP (100 pmol/5 µl) treatment on acute UV-A-induced retinal damage. We measured the thickness of nuclear and plexiform layers as well as the number of cells in the outer nuclear and inner nuclear layers and in the ganglion cell layer. Outer limiting membrane-inner limiting membrane distances in the cross-section of the retina were also examined. Our results show that UV-A light-induced retinal damage led to severe degeneration in the photoreceptor layer, and in the outer and inner nuclear layers. Alteration in the plexiform layers was also observed. We found that post-irradiation PACAP treatment significantly attenuated the UV-A-induced retinal damage. Our results provide the basis for future clinical application of PACAP treatment in retinal degeneration and may have clinical implications in several ophthalmic diseases.
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Affiliation(s)
- Tamas Atlasz
- Department of Sportbiology, University of Pecs, Pecs, Hungary
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Nakata M, Shintani N, Hashimoto H, Baba A, Yada T. Intra-islet PACAP protects pancreatic β-cells against glucotoxicity and lipotoxicity. J Mol Neurosci 2010; 42:404-10. [PMID: 20461496 DOI: 10.1007/s12031-010-9383-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 04/21/2010] [Indexed: 01/11/2023]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP), a potent insulinotropin, is localized in pancreatic islets. Hyperglycemia and hyperlipidemia impair islet β-cell functions, being recognized as glucotoxicity and lipotoxicity. In this study, we examined whether endogenous PACAP protects islet β-cells against the toxicities. Pancreatic islets were prepared from wild-type and PACAP-null mice, and cultured for 2 days in control conditions containing 5.6 mM glucose, those with elevated 25 mM glucose and those supplemented with 0.4 mM palmitate. After culture in control conditions, a rise in the superfusate glucose concentration from 2.8 mM to a physiologic 8.3 mM increased cytosolic Ca(2+) concentration ([Ca(2+)](i)) in both wild-type and PACAP-null mouse islets. In contrast, after culture with high glucose or palmitate, the glucose-induced first phase [Ca(2+)](i) increases were severely impaired in islets of PACAP-null mice while they were preserved in islets of wild-type mice. Treatment with high glucose or palmitate also impaired glucose-induced insulin secretion in islets and increased mRNA expression of uncoupling protein 2 (UCP2) in islets of PACAP-null, but not wild-type, mice. These data indicate that islet-produced PACAP protects β-cells from deteriorating action of high glucose and palmitate at least partly by blocking the elevation of UCP2, suggesting an anti-diabetic role for PACAP.
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Affiliation(s)
- Masanori Nakata
- Department of Physiology, Division of Integrative Physiology, School of Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
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Szabadfi K, Mester L, Reglodi D, Kiss P, Babai N, Racz B, Kovacs K, Szabo A, Tamas A, Gabriel R, Atlasz T. Novel neuroprotective strategies in ischemic retinal lesions. Int J Mol Sci 2010; 11:544-561. [PMID: 20386654 PMCID: PMC2852854 DOI: 10.3390/ijms11020544] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 01/27/2010] [Accepted: 01/27/2010] [Indexed: 02/04/2023] Open
Abstract
Retinal ischemia can be effectively modeled by permanent bilateral common carotid artery occlusion, which leads to chronic hypoperfusion-induced degeneration in the entire rat retina. The complex pathways leading to retinal cell death offer a complex approach of neuroprotective strategies. In the present review we summarize recent findings with different neuroprotective candidate molecules. We describe the protective effects of intravitreal treatment with: (i) urocortin 2; (ii) a mitochondrial ATP-sensitive K+ channel opener, diazoxide; (iii) a neurotrophic factor, pituitary adenylate cyclase activating polypeptide; and (iv) a novel poly(ADP-ribose) polymerase inhibitor (HO3089). The retinoprotective effects are demonstrated with morphological description and effects on apoptotic pathways using molecular biological techniques.
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Affiliation(s)
- Krisztina Szabadfi
- Department of Experimental Zoology and Neurobiology, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(K.S.);
(N.B.);
(R.G.)
| | - Laszlo Mester
- Department of Biochemistry and Medical Chemistry, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(L.M.);
(B.R.);
(K.K.);
(A.S.)
| | - Dora Reglodi
- Department of Anatomy, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(D.R.);
(P.K.);
(A.T.)
| | - Peter Kiss
- Department of Anatomy, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(D.R.);
(P.K.);
(A.T.)
| | - Norbert Babai
- Department of Experimental Zoology and Neurobiology, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(K.S.);
(N.B.);
(R.G.)
| | - Boglarka Racz
- Department of Biochemistry and Medical Chemistry, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(L.M.);
(B.R.);
(K.K.);
(A.S.)
| | - Krisztina Kovacs
- Department of Biochemistry and Medical Chemistry, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(L.M.);
(B.R.);
(K.K.);
(A.S.)
| | - Aliz Szabo
- Department of Biochemistry and Medical Chemistry, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(L.M.);
(B.R.);
(K.K.);
(A.S.)
| | - Andrea Tamas
- Department of Anatomy, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(D.R.);
(P.K.);
(A.T.)
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(K.S.);
(N.B.);
(R.G.)
| | - Tamas Atlasz
- Department of Experimental Zoology and Neurobiology, University of Pecs, H-7624 Pecs, Hungary; E-Mails:
(K.S.);
(N.B.);
(R.G.)
- Department of Sportbiology, University of Pecs, H-7624 Pecs, Hungary
- Author to whom correspondence should be addressed; E-Mail:
; Tel.: +36-72-503-600/4613; Fax: +36-72-501-517
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Vaudry D, Falluel-Morel A, Bourgault S, Basille M, Burel D, Wurtz O, Fournier A, Chow BKC, Hashimoto H, Galas L, Vaudry H. Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery. Pharmacol Rev 2009; 61:283-357. [DOI: 10.1124/pr.109.001370] [Citation(s) in RCA: 829] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Atlasz T, Szabadfi K, Kiss P, Tamas A, Toth G, Reglodi D, Gabriel R. Evaluation of the protective effects of PACAP with cell-specific markers in ischemia-induced retinal degeneration. Brain Res Bull 2009; 81:497-504. [PMID: 19751807 DOI: 10.1016/j.brainresbull.2009.09.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 09/08/2009] [Indexed: 01/26/2023]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is a neurotrophic and neuroprotective peptide that has been shown to exert protective effects in different neuronal injuries, such as traumatic brain injury, models of neurodegenerative diseases and cerebral ischemia. We have provided evidence that PACAP is neuroprotective in several models of retinal degeneration in vivo. In our previous studies we showed that PACAP treatment significantly ameliorated the damaging effects of permanent bilateral common carotid artery occlusion (BCCAO). In the present study cell-type-specific markers were used in the same models in order to further specify the protective effects of PACAP. In rats BCCAO led to severe degeneration of all retinal layers that was attenuated by PACAP (100 pmol) administered unilaterally immediately following BCCAO into the vitreous body of one eye. Retinas were processed for immunohistochemistry after 3 weeks. Immunolabeling was executed for vesicular glutamate transporter 1 (VGLUT 1), vesicular gamma-aminobutyric acid transporter (VGAT), protein kinase Calpha (PKCalpha), glial fibrillary acidic protein (GFAP) and calcium-binding proteins, such as calbindin, calretinin, parvalbumin. In BCCAO retinas, intensity of immunopositivity for all antisera was dramatically decreased, except in the case of GFAP. In PACAP-treated retinas, immunostaining was similar to that of the control animals. In summary, our study presented immunohistochemical identification of cell types sensitive to chronic retinal hypoperfusion and the protective effects of PACAP. This analysis revealed that the retinoprotective effects of PACAP are not phenotype-specific, but it rather influences general cytoprotective pathways irrespective of the neuronal subtypes in the retina subjected to chronic hypoperfusion.
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Affiliation(s)
- Tamas Atlasz
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary.
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Staines DR, Brenu EW, Marshall-Gradisnik S. Vasoactive neuropeptides in clinical ophthalmology: An association with autoimmune retinopathy? Clin Ophthalmol 2009; 3:259-61. [PMID: 19668576 PMCID: PMC2709019 DOI: 10.2147/opth.s5356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The mammalian eye is protected against pathogens and inflammation in a relatively immune-privileged environment. Stringent mechanisms are activated that regulate external injury, infection, and autoimmunity. The eye contains a variety of cells expressing vasoactive neuropeptides (VNs), and their receptors, located in the sclera, cornea, iris, ciliary body, ciliary process, and the retina. VNs are important activators of adenylate cyclase, deriving cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP). Impairment of VN function would arguably impede cAMP production and impede utilization of ATP. Thus VN autoimmunity may be an etiological factor in retinopathy involving perturbations of purinergic signaling. A sound blood supply is necessary for the existence and functional properties of the retina. This paper postulates that impairments in the endothelial barriers and the blood–retinal barrier, as well as certain inflammatory responses, may arise from disruption to VN function. Phosphodiesterase inhibitors and purinergic modulators may have a role in the treatment of postulated VN autoimmune retinopathy.
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Affiliation(s)
- Donald R Staines
- Queensland Health, Gold Coast Population Health Unit, Southport, Gold Coast, Queensland, Australia.
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Zhang XY, Hayasaka S, Chi ZL, Cui HS, Hayasaka Y. Effect of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) on IL-6, IL-8, and MCP-1 Expression in Human Retinal Pigment Epithelial Cell Line. Curr Eye Res 2009; 30:1105-11. [PMID: 16354624 DOI: 10.1080/02713680500421444] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE To examine pituitary adenylate cyclase-activating polypeptide (PACAP) receptors (PAC1, VPAC1, and VPAC2) mRNA and the effect of PACAP on interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1) expression in human retinal pigment epithelial cell line (ARPE-19) stimulated with interleukin-1beta (IL-1beta). METHODS Expression of PACAP receptor mRNA was examined by reverse transcription polymerase chain reaction (RT-PCR). PACAP and IL-1beta were added to serum-free medium. IL-6, IL-8, and MCP-1 mRNA were measured by real-time PCR. IL-6, IL-8, and MCP-1 protein concentrations were measured using enzyme-linked immunosorbent assay. Nuclear factor kappaB (NF-kappaB) translocation was examined by immunofluorescence. RESULTS PAC1 and VCAP1 receptors mRNA were expressed in unstimulated cells. VCAP2 mRNA was expressed in cells stimulated with IL-1beta. IL-1beta stimulated IL-6, IL-8, and MCP-1 mRNA expression and protein levels. PACAP (10(- 7) to 10(- 6) M) inhibited IL-1beta -stimulated IL-6, IL-8, and MCP-1 mRNA and protein levels. Immunofluorescence of NF-kappaB in the nucleus was dense 30 min after stimulation with IL-1beta, and it was decreased by PACAP. CONCLUSIONS ARPE-19 cells had PACAP receptors mRNA. PACAP inhibited IL-6, IL-8, and MCP-1 expression and protein secretion. Possibly, the effect on cytokines may be via suppression of NF-kappaB translocation.
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Affiliation(s)
- Xue-Yun Zhang
- Department of Ophthalmology, Toyama Medical and Pharmaceutical University, Toyama, Japan.
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Tomimatsu N, Arakawa Y. Survival-promoting activity of pituitary adenylate cyclase-activating polypeptide in the presence of phosphodiesterase inhibitors on rat motoneurons in culture: cAMP-protein kinase A-mediated survival. J Neurochem 2008; 107:628-35. [PMID: 18717811 DOI: 10.1111/j.1471-4159.2008.05638.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to be neurotrophic or neuroprotective in various neurons in culture. It is expressed in spinal motoneurons in vivo and its expression is increased markedly after axotomy, suggesting a neuroprotective role via an autocrine mechanism. However, neurotrophic activity of PACAP has not been reported for motoneurons. In the present study, we investigated the effects of PACAP on rat motoneurons in culture. In the presence of a phosphodiesterase inhibitor, PACAP showed significant neurotrophic activity at concentrations as low as 0.01 nM. Previously, we found that glutamate was excitotoxic to motoneurons even in the presence of brain-derived neurotrophic factor, which is neurotrophic for motoneurons. PACAP with a phosphodiesterase inhibitor protected motoneurons against this excitotoxicity. The activity of PACAP was inhibited by the protein kinase A inhibitor N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinolinesulfonamide dihydrochloride, as was the case with the activity of forskolin, suggesting downstream involvement of a cAMP-protein kinase A signaling pathway. The present results may suggest a physiological role of PACAP in vivo, and implicate the PACAP-cAMP signaling pathway for the possible therapeutic target of amyotrophic lateral sclerosis as glutamate excitotoxicity was suggested in sporadic amyotrophic lateral sclerosis.
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Affiliation(s)
- Naoko Tomimatsu
- Clinical Research Center, The University of Tokyo Hospital, Faculty of Medicine, University of Tokyo, Tokyo, Japan
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Gaal V, Mark L, Kiss P, Kustos I, Tamas A, Kocsis B, Lubics A, Nemeth V, Nemeth A, Lujber L, Pytel J, Toth G, Reglodi D. Investigation of the effects of PACAP on the composition of tear and endolymph proteins. J Mol Neurosci 2008; 36:321-9. [PMID: 18421426 DOI: 10.1007/s12031-008-9067-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 03/12/2008] [Indexed: 12/30/2022]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is widely distributed in ocular tissues, including the lacrimal gland. PACAP has been shown to influence the activity of several exocrine glands, but its effects on the composition of the tear film are not known yet. Similarly, the presence of PACAP has already been shown in the inner ear, but it is not known whether PACAP influences the composition of the endolymph. The aim of the present study was to investigate whether systemic injection of PACAP has any modulatory effects on the protein composition of the tear film and endolymph using chip electrophoresis and mass spectrometry analysis. Tear and endolymph samples were collected from rats and chickens, respectively, at various time points after systemic injection of PACAP. Fluid samples were further processed for chip electrophoretic studies. No difference was found in the protein composition of the endolymph between control and PACAP-treated animals. In contrast, tear samples showed a marked difference after PACAP treatment. Proteins in the molecular range 50-70 kDa, which showed a different chip electropherogram profile in every PACAP-treated sample, were further analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. PACAP treatment induced a repression in certain keratins, while others were induced after PACAP injection. Furthermore, PACAP treatment decreased aldehyde dehydrogenase expression. The present study provides a base for further studies on the in vivo effects of PACAP on the composition of tear film. These investigations may have important clinical relevance because of the noninvasive sample collection, the correlation between tear proteins and ocular diseases, and the possible presence of biomarkers for both ophthalmological and systemic pathological conditions.
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Affiliation(s)
- Valeria Gaal
- Department of Ophthalmology, University of Pecs, Ifjusag u 13, 7624, Pecs, Hungary
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Atlasz T, Szabadfi K, Kiss P, Babai N, Koszegi Z, Tamas A, Reglodi D, Gabriel R. PACAP-Mediated Neuroprotection of Neurochemically Identified Cell Types in MSG-Induced Retinal Degeneration. J Mol Neurosci 2008; 36:97-104. [DOI: 10.1007/s12031-008-9059-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Accepted: 02/22/2008] [Indexed: 11/28/2022]
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Shieh PC, Tsao CW, Li JS, Wu HT, Wen YJ, Kou DH, Cheng JT. Role of pituitary adenylate cyclase-activating polypeptide (PACAP) in the action of ginsenoside Rh2 against beta-amyloid-induced inhibition of rat brain astrocytes. Neurosci Lett 2008; 434:1-5. [DOI: 10.1016/j.neulet.2007.12.032] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 12/10/2007] [Accepted: 12/18/2007] [Indexed: 12/30/2022]
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Atlasz T, Babai N, Kiss P, Reglodi D, Tamás A, Szabadfi K, Tóth G, Hegyi O, Lubics A, Gábriel R. Pituitary adenylate cyclase activating polypeptide is protective in bilateral carotid occlusion-induced retinal lesion in rats. Gen Comp Endocrinol 2007; 153:108-14. [PMID: 17289046 DOI: 10.1016/j.ygcen.2006.12.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 12/21/2006] [Accepted: 12/25/2006] [Indexed: 10/23/2022]
Abstract
Pituitary adenylate cyclase activating popypeptide (PACAP) is a pleiotropic neuropeptide, exerting neurotrophic and neuroprotective effects in numerous models of in vitro and in vivo nervous injuries. The aim of the present study was to investigate whether PACAP is neuroprotective in ischemic retinal damage. Adult male Wistar rats underwent bilateral carotid occlusion and PACAP was administered unilaterally into the vitreous body immediately following carotid occlusion. Retinas were analyzed three weeks after the injury. It was found that bilateral carotid occlusion led to a severe degeneration of all retinal layers. PACAP treatment significantly ameliorated the carotid occlusion-induced retinal damage: the overall thickness of the retina was significantly more than in control carotid occluded animals and the morphological characteristics of the photoreceptors showed nearly normal appearance. The outer plexiform layer remained discernible and the inner and outer nuclear layers were significantly thicker than in control animals. In summary, our present study provides evidence, for the first time, that PACAP attenuates ischemic retinal degeneration.
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Affiliation(s)
- Tamás Atlasz
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
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Staines DR. Does autoimmunity of endogenous vasoactive neuropeptides cause retinopathy in humans? Med Hypotheses 2007; 70:137-40. [PMID: 17560049 PMCID: PMC7130865 DOI: 10.1016/j.mehy.2007.04.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Accepted: 04/17/2007] [Indexed: 01/17/2023]
Abstract
Immune privilege is a physiologic mechanism within the eye which protects it against pathogens, while also protecting it from inflammation. Immunological mechanisms in the eye must be tightly regulated to ensure externally mediated injury and infection or internally mediated autoimmunity do not exceed self-defence tolerance. Vasoactive neuropeptides (VNs) including vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase polypeptide (PACAP) and their receptors exist in the mammalian eye including the sclera, cornea, iris, ciliary body, ciliary process and the retina and may have a role in protecting these normally immune privileged sites. VN receptors are class II G protein-coupled receptors (GPCRs) which couple primarily to the adenylate cyclase (AC)-cyclic AMP pathway. A sound blood supply is essential for retinal survival hence vascular compromise will have serious consequences. Retinal vasculitis is a potentially blinding condition with a strong association with systemic inflammatory diseases. Compromise of the endothelial barriers and the blood retina barrier (BRB) may instigate inflammatory responses setting up a chain of events involving VNs in a manner which provokes autoimmunity to them. Protection from BRB breakdown may be linked to nitric oxide (NO) effects and actions of phosphodiesterase inhibitors and cAMP production. Induced NO expressed under influences of inflammatory mediators evokes neurodegeneration and cell apoptosis and may lead to serious ocular disease including retinal injury. Other inflammatory mediators also play a role in retinal pathology. PACAP and glutamate are co-stored in the retinohypothalamic tract and PACAP attenuates glutamate induced neurotoxicity in cultured retinal neurons suggesting that compromise of this VN would have significant detrimental impact on retinal viability though glutamate toxicity. Additional effects of VN compromise would possibly occur through unopposed vasoconstriction and inflammation. Proof of this hypothesis has important implications for treatment and prevention of autoimmune retinopathy and blindness as a number of therapeutic pathways may be opened. Importantly for therapeutic contexts cAMP effects are maintained by phosphodiesterase (PDE) inhibitors which could be used in VN autoimmune disorders. A compelling case may exist to undertake a therapeutic trial of VN replacement, PDE inhibitors and other agents in autoimmune retinopathies resulting from possible VN autoimmunity.
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Affiliation(s)
- Donald R Staines
- Gold Coast Population Health Unit, 10-12 Young Street, Southport 4215, Qld., Australia.
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Effects of pituitary adenylate cyclase activating polypeptide (PACAP) on the PKA-bad-14-3-3 signaling pathway in glutamate-induced retinal injury in neonatal rats. Neurotox Res 2007; 12:95-104. [DOI: 10.1007/bf03033918] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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van Landeghem FKH, Weiss T, von Deimling A. Expression of PACAP and glutamate transporter proteins in satellite oligodendrocytes of the human CNS. ACTA ACUST UNITED AC 2007; 142:52-9. [PMID: 17346813 DOI: 10.1016/j.regpep.2007.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 01/23/2007] [Accepted: 01/24/2007] [Indexed: 11/23/2022]
Abstract
White matter oligodendrocytes have been shown to actively regulate extracellular glutamate levels in the CNS. Such function has yet not been examined in satellite oligodendrocytes of gray matter. Similar to those in white matter, satellite oligodendrocytes are involved in myelination. In addition, they modulate the activity of surrounding neurons. This study examined whether satellite oligodendrocytes express PACAP and glutamate transporter proteins and whether this expression is influenced by global ischemia. We demonstrated expression of PACAP27 and PACAP38 in a major fraction of satellite oligodendrocytes in normal neocortex and hippocampus of human brain tissues obtained post-mortem. All three glutamate transporters EAAT1, EAAT2 and EAAT3 were expressed in satellite oligodendrocytes from these tissues. Thus, satellite oligodendrocytes may participate in the perineuronal glutamate homeostasis. Following transient global ischemia, the total number of satellite oligodendrocytes expressing PACAP or glutamate transporter proteins was significantly decreased in cerebral neocortex and hippocampus. However, alterations of PACAP and glutamate transporter protein expression were region and time specific. In satellite oligodendrocytes of CA1 an early strong reduction of PACAP and glutamate transporter expression was observed. This contrasted with late reduction of PACAP27, PACAP38 and glutamate transporters EAAT1, EAAT2 and EAAT3 in satellite oligodendrocytes of neocortex. Further studies should clarify whether these alterations in protein expression are primary or secondary to neuronal cell death.
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Affiliation(s)
- Frank K H van Landeghem
- Institute of Neuropathology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany.
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Rácz B, Gallyas F, Kiss P, Tóth G, Hegyi O, Gasz B, Borsiczky B, Ferencz A, Roth E, Tamás A, Lengvári I, Lubics A, Reglodi D. The neuroprotective effects of PACAP in monosodium glutamate-induced retinal lesion involve inhibition of proapoptotic signaling pathways. ACTA ACUST UNITED AC 2006; 137:20-6. [PMID: 16945433 DOI: 10.1016/j.regpep.2006.02.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 02/10/2006] [Accepted: 02/27/2006] [Indexed: 11/20/2022]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) and its receptors are present in the retina and exert several distinct functions. PACAP has well-known neuroprotective effects in neuronal cultures in vitro and against different insults in vivo. Recently we have shown that PACAP is neuroprotective against monosodium glutamate (MSG)-induced retinal degeneration. In the present study we investigated the possible signal transduction pathways involved in the protective effect of intravitreal PACAP administration against apoptotic retinal degeneration induced by neonatal MSG treatment. MSG induced activation of proapoptotic signaling proteins and reduced the levels of antiapoptotic molecules in neonatal retinas. Co-treatment with PACAP attenuated the MSG-induced activation of caspase-3 and JNK, inhibited the MSG-induced cytosolic translocation of apoptosis inducing factor (AIF) and cytochrome c, and increased the level of phospho-Bad. Furthermore, PACAP treatment alone decreased cytosolic AIF and cytochrome c levels, while PACAP6-38 increased cytochrome c release, caspase-3 and JNK activity and decreased phospho-Bad activity. In summary, our results show that PACAP treatment attenuated the MSG-induced changes in apoptotic signaling molecules in vivo and suggest that also endogenously present PACAP has neuroprotective effects. These results may have further clinical implications in reducing glutamate-induced excitotoxicity in several ophthalmic diseases.
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Affiliation(s)
- Boglárka Rácz
- Department of Surgical Research and Techniques, University of Pecs, Hungary
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Chen Y, Samal B, Hamelink CR, Xiang CC, Chen Y, Chen M, Vaudry D, Brownstein MJ, Hallenbeck JM, Eiden LE. Neuroprotection by endogenous and exogenous PACAP following stroke. ACTA ACUST UNITED AC 2006; 137:4-19. [PMID: 17027094 PMCID: PMC4183206 DOI: 10.1016/j.regpep.2006.06.016] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 06/13/2006] [Accepted: 06/13/2006] [Indexed: 11/28/2022]
Abstract
We investigated the effects of PACAP treatment, and endogenous PACAP deficiency, on infarct volume, neurological function, and the cerebrocortical transcriptional response in a mouse model of stroke, middle cerebral artery occlusion (MCAO). PACAP-38 administered i.v. or i.c.v. 1 h after MCAO significantly reduced infarct volume, and ameliorated functional motor deficits measured 24 h later in wild-type mice. Infarct volumes and neurological deficits (walking faults) were both greater in PACAP-deficient than in wild-type mice, but treatment with PACAP reduced lesion volume and neurological deficits in PACAP-deficient mice to the same level of improvement as in wild-type mice. A 35,546-clone mouse cDNA microarray was used to investigate cortical transcriptional changes associated with cerebral ischemia in wild-type and PACAP-deficient mice, and with PACAP treatment after MCAO in wild-type mice. 229 known (named) transcripts were increased (228) or decreased (1) in abundance at least 50% following cerebral ischemia in wild-type mice. 49 transcripts were significantly up-regulated only at 1 h post-MCAO (acute response transcripts), 142 were up-regulated only at 24 h post-MCAO (delayed response transcripts) and 37 transcripts were up-regulated at both times (sustained response transcripts). More than half of these are transcripts not previously reported to be altered in ischemia. A larger percentage of genes up-regulated at 24 hr than at 1 hr required endogenous PACAP, suggesting a more prominent role for PACAP in later response to injury than in the initial response. This is consistent with a neuroprotective role for PACAP in late response to injury, i.e., even when administered 1 hr or more after MCAO. Putative injury effector transcripts regulated by PACAP include beta-actin, midline 2, and metallothionein 1. Potential neuroprotective transcripts include several demonstrated to be PACAP-regulated in other contexts. Prominent among these were transcripts encoding the PACAP-regulated gene Ier3, and the neuropeptides enkephalin, substance P (tachykinin 1), and neurotensin.
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Affiliation(s)
- Yun Chen
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, NIH, Bethesda, MD, 20892, USA
| | - Babru Samal
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, NIH, Bethesda, MD, 20892, USA
| | - Carol R. Hamelink
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, NIH, Bethesda, MD, 20892, USA
| | - Charlie C. Xiang
- Laboratory of Genetics, National Institute of Mental Health, NIH, Bethesda, MD, 20892, USA
| | - Yong Chen
- Stroke Branch, National Institute of Neurological Diseases and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Mei Chen
- Laboratory of Genetics, National Institute of Mental Health, NIH, Bethesda, MD, 20892, USA
| | - David Vaudry
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, NIH, Bethesda, MD, 20892, USA
| | - Michael J. Brownstein
- Laboratory of Genetics, National Institute of Mental Health, NIH, Bethesda, MD, 20892, USA
| | - John M. Hallenbeck
- Stroke Branch, National Institute of Neurological Diseases and Stroke, NIH, Bethesda, MD, 20892, USA
| | - Lee E. Eiden
- Corresponding author. Tel.: +1 301 496 4110; fax: +1 301 402 1748. (L.E. Eiden)
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Tamás A, Zsombok A, Farkas O, Reglödi D, Pál J, Büki A, Lengvári I, Povlishock JT, Dóczi T. Postinjury administration of pituitary adenylate cyclase activating polypeptide (PACAP) attenuates traumatically induced axonal injury in rats. J Neurotrauma 2006; 23:686-95. [PMID: 16689670 DOI: 10.1089/neu.2006.23.686] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) has several different actions in the nervous system. Numerous studies have shown its neuroprotective effects both in vitro and in vivo. Previously, it has been demonstrated that PACAP reduces brain damage in rat models of global and focal cerebral ischemia. Based on the protective effects of PACAP in cerebral ischemia and the presence of common pathogenic mechanisms in cerebral ischemia and traumatic brain injury (TBI), the aim of the present study was to investigate the possible protective effect of PACAP administered 30 min or 1 h postinjury in a rat model of diffuse axonal injury. Adult Wistar male rats were subjected to impact acceleration, and PACAP was administered intracerebroventricularly 30 min (n = 4), and 1 h after the injury (n = 5). Control animals received the same volume of vehicle at both time-points (n = 5). Two hours after the injury, brains were processed for immunohistochemical localization of damaged axonal profiles displaying either beta-amyloid precursor protein (beta-APP) or RMO-14 immunoreactivity, both considered markers of specific features of traumatic axonal injury. Our results show that treatment with PACAP (100 microg) 30 min or 1 h after the induction of TBI resulted in a significant reduction of the density of beta-APP-immunopositive axon profiles in the corticospinal tract (CSpT). There was no significant difference between the density of beta-APP-immunopositive axons in the medial longitudinal fascicle (MLF). PACAP treatment did not result in significantly different number of RMO-14-immunopositive axonal profiles in either brain areas 2 hours post-injury compared to normal animals. While the results of this study highlighted the complexity of the pathogenesis and manifestation of diffuse axonal injury, they also indicate that PACAP should be considered a potential therapeutic agent in TBI.
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Affiliation(s)
- Andrea Tamás
- Department of Anatomy (Neurohumoral Regulations Research Group of the Hungarian Academy of Sciences), University of Pécs, Medical Faculty, Pécs, Hungary.
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Nakatani M, Seki T, Shinohara Y, Taki C, Nishimura S, Takaki A, Shioda S. Pituitary adenylate cyclase-activating peptide (PACAP) stimulates production of interleukin-6 in rat Müller cells. Peptides 2006; 27:1871-6. [PMID: 16427158 DOI: 10.1016/j.peptides.2005.12.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Revised: 12/20/2005] [Accepted: 12/20/2005] [Indexed: 11/24/2022]
Abstract
Pituitary adenylate cyclase-activating peptide (PACAP) is known to regulate not only neurons but also astrocytes. Here, we investigated, both in vitro and in vivo, the effects of PACAP38 on rat Müller cells, which are the predominant glial element in the retina. Müller cells isolated from juvenile Wistar rats were treated with PACAP38 or PACAP6-38, a PACAP selective antagonist. Cell proliferation was determined by measuring the incorporation of bromodeoxyuridine with ELISA. Interleukin-6 (IL-6) levels in the culture medium were determined by a bioassay using B9 cells, IL-6 dependent hybridoma. In adult Wistar rats, the expression of IL-6 in the retina after intravitreal injection of PACAP38 (10 pmol) was assessed by immunohistochemistry. PACAP38 stimulated IL-6 production in Müller cells at a concentration as low as 10(-12) M, which did not induce cell proliferation. This elevation of IL-6 production was inhibited by PACAP6-38. Radial IL-6 expression was observed throughout the retina at 2 and 3 days after PACAP38 injection. These data demonstrate that Müller cells are one of the target cells for PACAP. IL-6, which is released from Müller cells with stimulation by PACAP, may play a significant role in the retina.
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Affiliation(s)
- Masayoshi Nakatani
- Bioengineering Institute, Assessment Research Department, Nidek Co. Ltd., 6-209-1 Miyakitadori Gamagori-shi, Aichi 443-0022, Japan.
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Martin B, Lopez de Maturana R, Brenneman R, Walent T, Mattson MP, Maudsley S. Class II G protein-coupled receptors and their ligands in neuronal function and protection. Neuromolecular Med 2005; 7:3-36. [PMID: 16052036 PMCID: PMC2636744 DOI: 10.1385/nmm:7:1-2:003] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2005] [Accepted: 01/26/2005] [Indexed: 12/20/2022]
Abstract
G protein-coupled receptors (GPCRs) play pivotal roles in regulating the function and plasticity of neuronal circuits in the nervous system. Among the myriad of GPCRs expressed in neural cells, class II GPCRs which couples predominantly to the Gs-adenylate cyclase-cAMP signaling pathway, have recently received considerable attention for their involvement in regulating neuronal survival. Neuropeptides that activate class II GPCRs include secretin, glucagon-like peptides (GLP-1 and GLP-2), growth hormone-releasing hormone (GHRH), pituitary adenylate cyclase activating peptide (PACAP), corticotropin-releasing hormone (CRH), vasoactive intestinal peptide (VIP), parathyroid hormone (PTH), and calcitonin-related peptides. Studies of patients and animal and cell culture models, have revealed possible roles for class II GPCRs signaling in the pathogenesis of several prominent neurodegenerative conditions including stroke, Alzheimer's, Parkinson's, and Huntington's diseases. Many of the peptides that activate class II GPCRs promote neuron survival by increasing the resistance of the cells to oxidative, metabolic, and excitotoxic injury. A better understanding of the cellular and molecular mechanisms by which class II GPCRs signaling modulates neuronal survival and plasticity will likely lead to novel therapeutic interventions for neurodegenerative disorders.
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Affiliation(s)
- Bronwen Martin
- Laboratory of Neurosciences, National Institute on Ageing Intramural Research Program, Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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Babai N, Atlasz T, Tamás A, Reglödi D, Tóth G, Kiss P, Gábriel R. Degree of damage compensation by various PACAP treatments in monosodium glutamate-induced retinal degeneration. Neurotox Res 2005; 8:227-33. [PMID: 16371317 DOI: 10.1007/bf03033976] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) has been shown to be neuroprotective in retinal ischemia and monosodium L-glutamate (MSG)-induced retinal degeneration. Here we describe how different MSG treatments (1x and 3x application) cause retinal damage and finally lead to the destruction of the entire inner retina and how PACAP attenuates this effect. Newborn rats from both sexes were injected subcutaneously with 2 mg/g bodyweight MSG on postnatal days 1, 5 and 9. The left eye was left intact while we injected 5 microl PACAP38 solution (100 pmol) into the vitreous of the right eye with a Hamilton syringe at the time of (i) the first, (ii) the first two or (iii) all three MSG injections. Histological analysis has shown that the above described MSG treatment caused the entire inner plexiform layer (IPL) to degenerate, and the inner nuclear (INL) and ganglion cell layers (GCL) seemed fused. One time PACAP38 treatment at the first MSG application did not change the degenerative capacity of MSG. However, if animals received PACAP38 into the vitreous of the eye at the first 2 or all 3 times, a substantial protective effect could be observed. The IPL remained well discernible, the INL retained 2-3 cell rows and the number of cells in the GCL was substantially higher than in the MSG-treated retinas, and was not significantly different from that observed in the control tissue. We conclude that (i) 2 or 3 times PACAP treatment attenuates retinal degeneration; (ii) one PACAP treatment does not provide protection against repeated excitotoxic insults, and (iii) repeated application of PACAP under these experimental conditions may lead to a primed state in which further neurotoxic insults are ineffective.
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Affiliation(s)
- Norbert Babai
- Department of General Zoology and Neurobiology, Pécs University, Hungary
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Yamasaki M, Mishima HK, Yamashita H, Kashiwagi K, Murata K, Minamoto A, Inaba T. Neuroprotective effects of erythropoietin on glutamate and nitric oxide toxicity in primary cultured retinal ganglion cells. Brain Res 2005; 1050:15-26. [PMID: 15979589 DOI: 10.1016/j.brainres.2005.05.037] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2005] [Revised: 04/30/2005] [Accepted: 05/03/2005] [Indexed: 10/25/2022]
Abstract
Erythropoietin receptor (EpoR) is expressed in the central nervous system (CNS), however, no clear consensus has been obtained whether Epo acts as a prosurvival factor in neurons. Because retinal ganglion cell (RGC) death is a common cause of reduced visual function in several ocular diseases, we explored whether Epo might potentially be beneficial in protecting RGCs from glutamate and nitric oxide (NO)-induced cytotoxicity, using isolated RGCs by a two-step panning method. Brain-derived neurotrophic factor (BDNF) was used as a positive control. EpoR mRNA was expressed in isolated RGCs, and EpoR protein was expressed on the RGCs in the normal and ischemic retinas. Epo had less potential to improve the survival of primary RGCs in serum-free medium than BDNF. In these cells, BDNF, but not Epo, downregulated the expression of Bim, a proapoptotic Bcl-2 family member that plays a key role in cytokine-mediated cell survival, suggesting a possible mechanism for this difference. When RGCs were cultured with glutamate or an NO-generating reagent, the survival of RGCs was compromised, and Bcl-2 expression was decreased in these cells. Both Epo and BDNF significantly reduced RGC death induced by glutamate and NO. In agreement with this, these factors reversed the Bcl-2 expression. These findings suggest that Epo may be a potent neuroprotective therapeutic agent for the treatment of ocular diseases that are characterized by RGC death.
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Affiliation(s)
- Makiko Yamasaki
- Department of Ophthalmology and Visual Science, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Hiroshima 734-8551, Japan
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Wang G, Qi C, Fan GH, Zhou HY, Chen SD. PACAP protects neuronal differentiated PC12 cells against the neurotoxicity induced by a mitochondrial complex I inhibitor, rotenone. FEBS Lett 2005; 579:4005-11. [PMID: 16004991 DOI: 10.1016/j.febslet.2005.06.013] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Accepted: 06/07/2005] [Indexed: 12/21/2022]
Abstract
In vivo and in vitro studies have suggested a neuroprotective role for Pituitary adenylate cyclase activating polypeptide (PACAP) against neuronal insults. Here, we showed that PACAP27 protects against neurotoxicity induced by rotenone, a mitochondrial complex I inhibitor that has been implicated in the pathogenesis of Parkinson's disease (PD). The neuroprotective effect of PACAP27 was dose-dependent and blocked by its specific receptor antagonist, PACAP6-27. The effects of PACAP27 on rotenone-induced cell death were mimicked by dibutyryl-cAMP (db-cAMP), forskolin and prevented by the PKA inhibitor H89, the ERK inhibitor PD98059 and the p38 inhibitor SB203580. PACAP27 administration blocked rotenone-induced increases in the level of caspase-3-like activity, whereas could not restore mitochondrial activity damaged by rotenone. Thus, our results demonstrate that PACAP27 has a neuroprotective role against rotenone-induced neurotoxicity in neuronal differentiated PC12 cells and the neuroprotective effects of PACAP are associated with activation of MAP kinase pathways by PKA and with inhibition of caspase-3 activity; the signaling mechanism appears to be mediated through mitochondrial-independent pathways.
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Affiliation(s)
- Gang Wang
- Department of Neurology & Institute of Neurology, Ruijin Hospital, Shanghai Second Medical University, Shanghai, China
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Shintani N, Suetake S, Hashimoto H, Koga K, Kasai A, Kawaguchi C, Morita Y, Hirose M, Sakai Y, Tomimoto S, Matsuda T, Baba A. Neuroprotective action of endogenous PACAP in cultured rat cortical neurons. ACTA ACUST UNITED AC 2005; 126:123-8. [PMID: 15620425 DOI: 10.1016/j.regpep.2004.08.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) exerts neurotrophic effects both in vitro and in vivo. Here we demonstrate the upregulation of PACAP mRNA expression in cultured rat cortical neurons after excitotoxic glutamate exposure, and the exacerbating effect of the PACAP receptor antagonist, PACAP(6-38), on neuronal viability. PACAP mRNA levels were increased up to 3.5-fold 8 h after glutamate exposure. PACAP(6-38) decreased the viability of cortical neurons, irrespective of whether the cells were exposed to glutamate or not. PACAP(6-38) also inhibited glutamate-induced expression of PACAP mRNA, suggesting that PACAP acts via an autocrine or paracrine mechanism to enhance PACAP expression itself. Glutamate exposure is known to increase brain-derived neurotrophic factor (BDNF) mRNA expression. This increased expression was markedly suppressed by PACAP(6-38). Our previous study has shown that PACAP stimulates the PACAP gene transcription in PC12 cells. Taken together, these data may suggest that endogenous PACAP regulates the expression of PACAP itself and BDNF. Although it may also be possible that PACAP(6-38)-induced death of PACAP and BDNF mRNA-expressing cells, per se, results in reduced levels of these mRNAs, the present results support the idea that endogenous PACAP has a neuroprotective action.
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Affiliation(s)
- Norihito Shintani
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
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Farkas O, Tamás A, Zsombok A, Reglodi D, Pál J, Büki A, Lengvári I, Povlishock JT, Dóczi T. Effects of pituitary adenylate cyclase activating polypeptide in a rat model of traumatic brain injury. ACTA ACUST UNITED AC 2005; 123:69-75. [PMID: 15518895 DOI: 10.1016/j.regpep.2004.05.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is a widely distributed neuropeptide that has numerous different actions. Recent studies have shown that PACAP exerts neuroprotective effects not only in vitro but also in vivo, in animal models of global and focal cerebral ischemia, Parkinson's disease and axonal injuries. Traumatic brain injury has an increasing mortality and morbidity and it evokes diffuse axonal injury which further contributes to its damaging effects. The aim of the present study was to examine the possible neuroprotective effect of PACAP in a rat model of diffuse axonal injury induced by impact acceleration. Axonal damage was assessed by immunohistochemistry using an antiserum against beta-amyloid precursor protein, a marker of altered axoplasmic transport considered as key feature in axonal injury. In these experiments, we have established the dose response curves for PACAP administration in traumatic axonal injury, demonstrating that a single post-injury intracerebroventricular injection of 100 microg PACAP significantly reduced the density of damaged, beta-amyloid precursor protein-immunoreactive axons in the corticospinal tract.
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Affiliation(s)
- Orsolya Farkas
- Department of Neurosurgery, University of Pécs, Medical Faculty, Hungary
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Onoue S, Endo K, Ohmori Y, Yamada S, Kimura R, Yajima T, Kashimoto K. Long-acting analogue of vasoactive intestinal peptide, [R15, 20, 21, L17]-VIP-GRR (IK312532), protects rat alveolar L2 cells from the cytotoxicity of cigarette smoke. REGULATORY PEPTIDES 2004; 123:193-9. [PMID: 15518912 DOI: 10.1016/j.regpep.2004.04.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) act as neurotransmitters in numerous biological responses. We previously reported that the replacement of Lys by Arg, and Met by Leu in VIP (IK312532; [Arg15, 20, 21, Leu17]-VIP) resulted in a significant improvement in metabolic stability and biological activity. In the present study, we investigated the effect of VIP and its related peptides including long-acting VIP derivative (IK312532) and PACAP27 on the cytotoxicity of cigarette smoke extract (CSE), a causative factor of chronic obstructive pulmonary disease (COPD), in rat alveolar L2 cells. RT-PCR displayed the dominant expression of mRNA for the VIP-specific VPAC2 receptor in L2 cells, and VIP and the related peptides showed the specific binding activity and potent stimulation of adenylate cyclase. CSE at a concentration of 0.1% or higher induced significant apoptotic death of L2 cells. Interestingly, the addition of neuropeptides at a concentration of 10(-11) M or higher in L2 cells with CSE (0.25%) resulted in significant attenuation of cell death with the deactivation of CSE-evoked caspase-3 activity. IK312532 was much stable against the enzymatic digestion compared to VIP, and the protective effect of IK312532 was 1.6-fold higher than that of VIP. Taken together with our previous report showing that IK312532 has long-acting relaxant activity in the lung, IK312532 may be a potential candidate for drug treatment of asthma and COPD.
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Affiliation(s)
- Satomi Onoue
- Health Science Division, Itoham Foods Inc., 1-2-1 Kubogaoka, Moriya, Ibaraki 302-0104, Japan.
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