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Tasma Z, Rees TA, Guo S, Tan S, O'Carroll SJ, Faull RLM, Curtis MA, Christensen SL, Hay DL, Walker CS. Pharmacology of PACAP and VIP receptors in the spinal cord highlights the importance of the PAC 1 receptor. Br J Pharmacol 2024; 181:2655-2675. [PMID: 38616050 DOI: 10.1111/bph.16376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 12/18/2023] [Accepted: 01/20/2024] [Indexed: 04/16/2024] Open
Abstract
BACKGROUND AND PURPOSE The spinal cord is a key structure involved in the transmission and modulation of pain. Pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP), are expressed in the spinal cord. These peptides activate G protein-coupled receptors (PAC1, VPAC1 and VPAC2) that could provide targets for the development of novel pain treatments. However, it is not clear which of these receptors are expressed within the spinal cord and how these receptors signal. EXPERIMENTAL APPROACH Dissociated rat spinal cord cultures were used to examine agonist and antagonist receptor pharmacology. Signalling profiles were determined for five signalling pathways. The expression of different PACAP and VIP receptors was then investigated in mouse, rat and human spinal cords using immunoblotting and immunofluorescence. KEY RESULTS PACAP, but not VIP, potently stimulated cAMP, IP1 accumulation and ERK and cAMP response element-binding protein (CREB) but not Akt phosphorylation in spinal cord cultures. Signalling was antagonised by M65 and PACAP6-38. PACAP-27 was more effectively antagonised than either PACAP-38 or VIP. The patterns of PAC1 and VPAC2 receptor-like immunoreactivity appeared to be distinct in the spinal cord. CONCLUSIONS AND IMPLICATIONS The pharmacological profile in the spinal cord suggested that a PAC1 receptor is the major functional receptor subtype present and thus likely mediates the nociceptive effects of the PACAP family of peptides in the spinal cord. However, the potential expression of both PAC1 and VPAC2 receptors in the spinal cord highlights that these receptors may play differential roles and are both possible therapeutic targets.
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MESH Headings
- Animals
- Spinal Cord/metabolism
- Spinal Cord/drug effects
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I/metabolism
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I/agonists
- Humans
- Pituitary Adenylate Cyclase-Activating Polypeptide/pharmacology
- Pituitary Adenylate Cyclase-Activating Polypeptide/metabolism
- Vasoactive Intestinal Peptide/metabolism
- Vasoactive Intestinal Peptide/pharmacology
- Mice
- Rats
- Signal Transduction/drug effects
- Receptors, Vasoactive Intestinal Peptide/metabolism
- Receptors, Vasoactive Intestinal Peptide/antagonists & inhibitors
- Cells, Cultured
- Rats, Sprague-Dawley
- Male
- Mice, Inbred C57BL
- Cyclic AMP/metabolism
- Receptors, Vasoactive Intestinal Peptide, Type II/metabolism
- Receptors, Vasoactive Intestinal Peptide, Type II/agonists
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Affiliation(s)
- Zoe Tasma
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Tayla A Rees
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
| | - Song Guo
- Department of Neurology, Danish Headache Center, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark
- Department of Odontology, Panum Institute, Faculty of Health, University of Copenhagen, Copenhagen, Denmark
| | - Sheryl Tan
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Simon J O'Carroll
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Sarah L Christensen
- Department of Neurology, Danish Headache Center, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark
| | - Debbie L Hay
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
- Department of Pharmacology and Toxicology, The University of Otago, Dunedin, New Zealand
| | - Christopher S Walker
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
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Kambe Y, Youkai M, Hashiguchi K, Sameshima Y, Takasaki I, Miyata A, Kurihara T. Spinal Astrocyte-Neuron Lactate Shuttle Contributes to the Pituitary Adenylate Cyclase-Activating Polypeptide/PAC1 Receptor-Induced Nociceptive Behaviors in Mice. Biomolecules 2022; 12:biom12121859. [PMID: 36551287 PMCID: PMC9775268 DOI: 10.3390/biom12121859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/15/2022] Open
Abstract
We have previously shown that spinal pituitary adenylate cyclase-activating polypeptide (PACAP)/PACAP type 1 (PAC1) receptor signaling triggered long-lasting nociceptive behaviors through astroglial activation in mice. Since astrocyte-neuron lactate shuttle (ANLS) could be essential for long-term synaptic facilitation, we aimed to elucidate a possible involvement of spinal ANLS in the development of the PACAP/PAC1 receptor-induced nociceptive behaviors. A single intrathecal administration of PACAP induced short-term spontaneous aversive behaviors, followed by long-lasting mechanical allodynia in mice. These nociceptive behaviors were inhibited by 1,4-dideoxy-1,4-imino-d-arabinitol (DAB), an inhibitor of glycogenolysis, and this inhibition was reversed by simultaneous L-lactate application. In the cultured spinal astrocytes, the PACAP-evoked glycogenolysis and L-lactate secretion were inhibited by DAB. In addition, a protein kinase C (PKC) inhibitor attenuated the PACAP-induced nociceptive behaviors as well as the PACAP-evoked glycogenolysis and L-lactate secretion. Finally, an inhibitor for the monocarboxylate transporters blocked the L-lactate secretion from the spinal astrocytes and inhibited the PACAP- and spinal nerve ligation-induced nociceptive behaviors. These results suggested that spinal PAC1 receptor-PKC-ANLS signaling contributed to the PACAP-induced nociceptive behaviors. This signaling system could be involved in the peripheral nerve injury-induced pain-like behaviors.
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Affiliation(s)
- Yuki Kambe
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Masafumi Youkai
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Kohei Hashiguchi
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Yoshimune Sameshima
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Ichiro Takasaki
- Department of Pharmacology, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan
| | - Atsuro Miyata
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
| | - Takashi Kurihara
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan
- Correspondence: ; Tel.: +81-99-275-5256
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3
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Takasaki I, Watanabe A, Yokai M, Watanabe Y, Hayakawa D, Nagashima R, Fukuchi M, Okada T, Toyooka N, Miyata A, Gouda H, Kurihara T. In Silico Screening Identified Novel Small-molecule Antagonists of PAC1 Receptor. J Pharmacol Exp Ther 2018; 365:1-8. [PMID: 29363578 DOI: 10.1124/jpet.117.245415] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 01/18/2018] [Indexed: 01/07/2023] Open
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors are present in the spinal dorsal horn and dorsal root ganglia, suggesting an important role of PACAP signaling systems in the modulation of spinal nociceptive transmission. Previously, we found that intrathecal injection of PACAP or maxadilan, a selective PACAP type I (PAC1) receptor agonist, induced transient aversive responses followed by a long-lasting mechanical allodynia in mice, suggesting that PACAP-PAC1 receptor systems are involved in chronic pain and that selective PAC1 antagonists may become a new class of analgesics. Although several PAC1 antagonists, such as PACAP 6-38, have been reported, all of them are peptide compounds. In the present study, we identified new small-molecule antagonists of the PAC1 receptor using in silico screening and in vitro/vivo pharmacological assays. The identified small-molecule compounds, named PA-8 and PA-9, dose dependently inhibited the phosphorylation of CREB induced by PACAP in PAC1-, but not VPAC1- or VPAC2-receptor-expressing CHO cells. PA-8 and PA-9 also dose dependently inhibited PACAP-induced cAMP elevation with an IC50 of 2.0 and 5.6 nM, respectively. In vivo pharmacological assays showed that intrathecal injection of these compounds blocked the induction of PACAP-induced aversive responses and mechanical allodynia in mice. In contrast, the compounds when administered alone exerted neither agonistic nor algesic actions in the in vitro/vivo assays. The compounds identified in the present study are new and the first small-molecule antagonists of the PAC1 receptor; they may become seed compounds for developing novel analgesics.
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Affiliation(s)
- Ichiro Takasaki
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Ai Watanabe
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Masafumi Yokai
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Yurie Watanabe
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Daichi Hayakawa
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Ryota Nagashima
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Mamoru Fukuchi
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Takuya Okada
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Naoki Toyooka
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Atsuro Miyata
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Hiroaki Gouda
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
| | - Takashi Kurihara
- Department of Pharmacology, Graduate School of Science and Engineering (I.T., A.W., R.N.), Graduate School of Innovative Life Sciences (I.T., T.O., N.T.), Department of Molecular Neurobiology, Graduate School of Medical and Pharmaceutical Sciences (M.F.), and Department of Bio-functional Molecular Engineering, Graduate School of Science and Engineering (T.O., N.T.), University of Toyama, Toyama, Japan; Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan (M.Y., A.M., T.K.); and Department of Analytical and Physical Chemistry, School of Pharmacy, Showa University, Tokyo, Japan (Y.W., D.H., H.G.)
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4
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Kambe Y, Kurihara T, Miyata A. [Astrocyte-neuron lactate shuttle, the major effector of astrocytic PACAP signaling for CNS functions]. Nihon Yakurigaku Zasshi 2018; 151:239-243. [PMID: 29887572 DOI: 10.1254/fpj.151.239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Transfer of lactate from astrocytes to neurons is activated when synaptic activity is increased, and this mechanism is now known as the astrocyte-neuron lactate shuttle (ANLS), that could account for the coupling between synaptic activity and energy delivery. Many lines of evidence suggested that ANLS contributes to neuronal activation or synaptic plasticity at the cellular level as well as learning/memory and cocaine addiction at the behavioral level. However, the candidate neurotransmitters which evoke ANLS activation are still under discussion. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neurotransmitter which distributed widely in central nervous system. Since PACAP might activate ANLS from very low concentration in cultured forebrain astrocytes, PACAP might be one of the candidates for the endogenous ANLS activator. In the present study, we investigated the potential relevance of PACAP/ANLS signaling in the learning/memory and spinal nociceptive transmission. In this study, we made the following findings: 1) PACAP could be an endogenous inducer for ANLS activation in central nervous system; 2) ANLS activation by PACAP/PAC1 receptor signaling contributed to learning/memory and induced long-lasting nociceptive behaviors; 3) PKC activation played an important role in the PACAP/PAC1 receptor-evoked ANLS.
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Affiliation(s)
- Yuki Kambe
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University
| | - Takashi Kurihara
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University
| | - Atsuro Miyata
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University
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Yokai M, Kurihara T, Miyata A. Spinal astrocytic activation contributes to both induction and maintenance of pituitary adenylate cyclase-activating polypeptide type 1 receptor-induced long-lasting mechanical allodynia in mice. Mol Pain 2016; 12:12/0/1744806916646383. [PMID: 27175011 PMCID: PMC4956379 DOI: 10.1177/1744806916646383] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 03/29/2016] [Indexed: 12/05/2022] Open
Abstract
Background Pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors are present in the spinal dorsal horn and dorsal root ganglia, suggesting an important role of PACAP–PACAP receptors signaling system in the modulation of spinal nociceptive transmission. We have previously reported that a single intrathecal injection of PACAP or a PACAP specific (PAC1) receptor selective agonist, maxadilan, in mice induced dose-dependent aversive behaviors, which lasted more than 30 min, and suggested that the maintenance of the nociceptive behaviors was associated with the spinal astrocytic activation. Results We found that a single intrathecal administration of PACAP or maxadilan also produced long-lasting hind paw mechanical allodynia, which persisted at least 84 days without affecting thermal nociceptive threshold. In contrast, intrathecal application of vasoactive intestinal polypeptide did not change mechanical threshold, and substance P, calcitonin gene-related peptide, or N-methyl-D-aspartate induced only transient mechanical allodynia, which disappeared within 21 days. Western blot and immunohistochemical analyses with an astrocytic marker, glial fibrillary acidic protein, revealed that the spinal PAC1 receptor stimulation caused sustained astrocytic activation, which also lasted more than 84 days. Intrathecal co-administration of L-α-aminoadipate, an astroglial toxin, with PACAP or maxadilan almost completely prevented the induction of the mechanical allodynia. Furthermore, intrathecal treatment of L-α-aminoadipate at 84 days after the PAC1 stimulation transiently reversed the mechanical allodynia accompanied by the reduction of glial fibrillary acidic protein expression level. Conclusion Our data suggest that spinal astrocytic activation triggered by the PAC1 receptor stimulation contributes to both induction and maintenance of the long-term mechanical allodynia.
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Affiliation(s)
- Masafumi Yokai
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima City, Japan
| | - Takashi Kurihara
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima City, Japan
| | - Atsuro Miyata
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima City, Japan
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Ohnou T, Yokai M, Kurihara T, Hasegawa-Moriyama M, Shimizu T, Inoue K, Kambe Y, Kanmura Y, Miyata A. Pituitary adenylate cyclase-activating polypeptide type 1 receptor signaling evokes long-lasting nociceptive behaviors through the activation of spinal astrocytes in mice. J Pharmacol Sci 2016; 130:194-203. [PMID: 26948958 DOI: 10.1016/j.jphs.2016.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 01/21/2016] [Accepted: 01/25/2016] [Indexed: 12/14/2022] Open
Abstract
Intrathecal (i.t.) administration of pituitary adenylate cyclase-activating polypeptide (PACAP) induces long-lasting nociceptive behaviors for more than 60 min in mice, while the involvement of PACAP type1 receptor (PAC1-R) has not been clarified yet. The present study investigated signaling mechanisms of the PACAP-induced prolonged nociceptive behaviors. Single i.t. injection of a selective PAC1-R agonist, maxadilan (Max), mimicked nociceptive behaviors in a dose-dependent manner similar to PACAP. Pre- or post-treatment of a selective PAC1-R antagonist, max.d.4, significantly inhibited the nociceptive behaviors by PACAP or Max. Coadministration of a protein kinase A inhibitor, Rp-8-Br-cAMPS, a mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase inhibitor, PD98059 or a c-Jun N-terminal kinase (JNK) inhibitor, SP600125, significantly inhibited the nociceptive behaviors by Max. Immunohistochemistry and immunoblotting analysis revealed that spinal administration of Max-induced ERK phosphorylation and JNK phosphorylation, and also augmented an astrocyte marker, glial fibrillary acidic protein in mouse spinal cord. Furthermore, an astroglial toxin, l-α-aminoadipate, significantly attenuated the development of the nociceptive behaviors and ERK phosphorylation by Max. These results suggest that the activation of spinal PAC1-R induces long-lasting nociception through the interaction of neurons and astrocytes.
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Affiliation(s)
- Tetsuya Ohnou
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan; Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Masafumi Yokai
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Takashi Kurihara
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Maiko Hasegawa-Moriyama
- Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Takao Shimizu
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Kazuhiko Inoue
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Yuki Kambe
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Yuichi Kanmura
- Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan
| | - Atsuro Miyata
- Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, Kagoshima 890-8544, Japan.
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Jansen-Olesen I, Baun M, Amrutkar DV, Ramachandran R, Christophersen DV, Olesen J. PACAP-38 but not VIP induces release of CGRP from trigeminal nucleus caudalis via a receptor distinct from the PAC1 receptor. Neuropeptides 2014; 48:53-64. [PMID: 24508136 DOI: 10.1016/j.npep.2014.01.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 11/07/2013] [Accepted: 01/07/2014] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To investigate if PACAP and VIP have an effect on CGRP release or NOS activity in the trigeminal ganglion and trigeminal nucleus caudalis and if there can be a difference in effect between PACAP and VIP on these two systems. Furthermore, we investigate if PACAP co-localize with CGRP and/or nNOS in the two tissues. BACKGROUND The structurally related neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating peptide-38 (PACAP-38) partially share receptors and are both potent vasodilators. However, PACAP-38 but not VIP is an efficient inducer of migraine attacks in migraineurs. Calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are two signaling molecules known to be involved in migraine. METHODS Rat tissue was used for all experiments. Release of CGRP induced by VIP and PACAP in dura mater, trigeminal ganglion (TG) and trigeminal nucleus caudalis (TNC) was quantified by EIA. Regulation of NOS-enzymes caused by VIP and PACAP was investigated in dura mater, TG and TNC by measuring the conversion of L-[3H]arginine to L-[3H]citrulline. Co-expression of PACAP, neuronal nitric oxide synthase (nNOS) and CGRP was explored by immunohistochemistry in TG and TNC. mRNA expression studies of VPAC1, VPAC2 and PAC1-receptors were performed by qRT-PCR. RESULTS PACAP-38 administered in increasing concentrations caused a concentration-dependent CGRP-release in the TNC, but not in TG. VIP was without effect in both tissues examined. The PAC1 receptor agonist maxadilan had no effect on CGRP release and the PAC1 antagonist M65 did not inhibit PACAP-38 induced CGRP release. PACAP-38 or VIP did not affect NOS activity in homogenates of TG and TNC. Quantitative PCR demonstrated the presence of VPAC1, VPAC2 and PAC1 receptors in TG and TNC. Immunohistochemistry of PACAP and CGRP showed co-expression in TG and TNC. PACAP and nNOS were co-localized in TG, but not in TNC. PACAP was found to co-localize with glutamine synthetase in TG satellite glial cells. CONCLUSION PACAP-38 cause release of CGRP from TNC but not from TG. We suggest that the release is not caused via activation of PAC1, VPAC1 or VPAC2 receptors. PACAP has no effect on NOS activity in TG or TNC. In TG PACAP was found in neuronal cells and in satellite glial cells. It co-localized with CGRP and nNOS in the neuronal cells. In TNC PACAP was co-localized with CGRP but not with nNOS.
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Affiliation(s)
- Inger Jansen-Olesen
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Glostrup, Denmark.
| | - Michael Baun
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Glostrup, Denmark
| | - Dipak V Amrutkar
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Glostrup, Denmark
| | - Roshni Ramachandran
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Glostrup, Denmark
| | - Daniel V Christophersen
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Glostrup, Denmark
| | - Jes Olesen
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Glostrup, Denmark
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Botz B, Imreh A, Sándor K, Elekes K, Szolcsányi J, Reglődi D, Quinn JP, Stewart J, Zimmer A, Hashimoto H, Helyes Z. Role of Pituitary Adenylate-Cyclase Activating Polypeptide and Tac1 gene derived tachykinins in sensory, motor and vascular functions under normal and neuropathic conditions. Peptides 2013; 43:105-12. [PMID: 23499760 DOI: 10.1016/j.peptides.2013.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/04/2013] [Accepted: 03/04/2013] [Indexed: 12/15/2022]
Abstract
Pituitary Adenylate-Cyclase Activating Polypeptide (PACAP) and Tac1 gene-encoded tachykinins (substance P: SP, neurokinin A: NKA) are expressed in capsaicin-sensitive nerves, but their role in nociception, inflammation and vasoregulation is unclear. Therefore, we investigated the function of these neuropeptides and the NK1 tachykinin receptor (from Tacr1 gene) in the partial sciatic nerve ligation-induced traumatic mononeuropathy model using gene deficient (PACAP(-/-), Tac1(-/-), and Tacr1(-/-)) mice. Mechanonociceptive threshold of the paw was measured with dynamic plantar aesthesiometry, motor coordination with Rota-Rod and cutaneous microcirculation with laser Doppler imaging. Neurogenic vasodilation was evoked by mustard oil stimulating sensory nerves. In wildtype mice 30-40% mechanical hyperalgesia developed one week after nerve ligation, which was not altered in Tac1(-/-) and Tacr1(-/-) mice, but was absent in PACAP(-/-) animals. Motor coordination of the PACAP(-/-) and Tac1(-/-) groups was significantly worse both before and after nerve ligation compared to their wildtypes, but it did not change in Tacr1(-/-) mice. Basal postoperative microcirculation on the plantar skin of PACAP(-/-) mice did not differ from the wildtypes, but was significantly lower in Tac1(-/-) and Tacr1(-/-) ones. In contrast, mustard oil-induced neurogenic vasodilation was significantly smaller in PACAP(-/-) mice, but not in Tacr1(-/-) and Tac1(-/-) animals. Both PACAP and SP/NKA, but not NK1 receptors participate in normal motor coordination. Tachykinins maintain basal cutaneous microcirculation. PACAP is a crucial mediator of neuropathic mechanical hyperalgesia and neurogenic vasodilation. Therefore identifying its target and developing selective, potent antagonists, might open promising new perspectives for the treatment of neuropathic pain and vascular complications.
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Affiliation(s)
- Bálint Botz
- Department of Pharmacology and Pharmacotherapy, University of Pécs, H-7624 Pécs, Szigeti u. 12, Hungary
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Pituitary adenylate cyclase-activating polypeptide plays a key role in nitroglycerol-induced trigeminovascular activation in mice. Neurobiol Dis 2012; 45:633-44. [DOI: 10.1016/j.nbd.2011.10.010] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 09/30/2011] [Accepted: 10/10/2011] [Indexed: 11/16/2022] Open
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10
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Sándor K, Kormos V, Botz B, Imreh A, Bölcskei K, Gaszner B, Markovics A, Szolcsányi J, Shintani N, Hashimoto H, Baba A, Reglodi D, Helyes Z. Impaired nocifensive behaviours and mechanical hyperalgesia, but enhanced thermal allodynia in pituitary adenylate cyclase-activating polypeptide deficient mice. Neuropeptides 2010; 44:363-71. [PMID: 20621353 DOI: 10.1016/j.npep.2010.06.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 06/10/2010] [Accepted: 06/12/2010] [Indexed: 01/31/2023]
Abstract
Pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) and its receptors (PAC1 and VPAC) have been shown in the spinal dorsal horn, dorsal root ganglia and sensory nerve terminals. Data concerning the role of PACAP in central pain transmission are controversial and we have recently published its divergent peripheral effects on nociceptive processes. The aim of the present study was to investigate acute somatic and visceral nocifensive behaviours, partial sciatic nerve ligation-evoked chronic neuropathic, as well as resiniferatoxin-induced inflammatory thermal and mechanical hyperalgesia in PACAP deficient (PACAP(-/-)) mice to elucidate its overall function in pain transmission. Neuronal activation was investigated with c-Fos immunohistochemistry. Paw lickings in the early (0-5 min) and late (20-45 min) phases of the formalin test were markedly reduced in PACAP(-/-) mice. Acetic acid-evoked abdominal contractions referring to acute visceral chemonociception was also significantly attenuated in PACAP knockout animals. In both models, the excitatory role of PACAP was supported by markedly greater c-Fos expression in the periaqueductal grey and the somatosensory cortex. In PACAP-deficient animals neuropathic mechanical hyperalgesia was absent, while c-Fos immunopositivity 20 days after the operation was significantly higher. In this chronic model, these neurons are likely to indicate the activation of secondary inhibitory pathways. Intraplantarly injected resiniferatoxin-evoked mechanical hyperalgesia involving both peripheral and central processes was decreased, but thermal allodynia mediated by only peripheral mechanisms was increased in PACAP(-/-) mice. These data clearly demonstrate an overall excitatory role of PACAP in pain transmission originating from both exteroceptive and interoceptive areas, it is also involved in central sensitization. This can be explained by the signal transduction mechanisms of its identified receptors, both PAC1 and VPAC activation leads to neuronal excitation. In contrast, it is an inhibitory mediator at the level of the peripheral sensory nerve endings and decreases their sensitization to heat with presently unknown mechanisms.
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Affiliation(s)
- K Sándor
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Pécs, Hungary
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11
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Nagata A, Tanaka T, Minezawa A, Poyurovsky M, Mayama T, Suzuki S, Hashimoto N, Yoshida T, Suyama K, Miyata A, Hosokawa H, Nakayama T, Tatsuno I. cAMP activation by PACAP/VIP stimulates IL-6 release and inhibits osteoblastic differentiation through VPAC2 receptor in osteoblastic MC3T3 cells. J Cell Physiol 2009; 221:75-83. [PMID: 19496170 DOI: 10.1002/jcp.21831] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP), a member of the glucagon/vasoactive intestinal peptide (VIP) superfamily, stimulates cyclic AMP accumulation initiating a variety of biological processes such as: neurotropic actions, immune and pituitary function, learning and memory, catecholamine biosynthesis and regulation of cardiopulmonary function. Both osteoclasts and osteoblasts have been shown to express receptors for PACAP/VIP implicated in their role in bone metabolism. To further understand the role of PACAP/VIP family in controlling bone metabolism, we investigated differentiation model of MC3T3-E1 cells, an osteoblastic cell line derived from mouse calvaria. Quantitative RT-PCR analysis demonstrated that MC3T3-E1 cells expressed only VPAC2 receptor and its expression was upregulated during osteoblastic differentiation, whereas VPAC1 and PAC1 receptors were not expressed. Consistent with expression of receptor subtype, both PACAP and VIP stimulate cAMP accumulation in a time- and dose-dependent manner with the similar potency in undifferentiated and differentiated cells, while Maxadilan, a specific agonist for PAC1-R, did not. Furthermore, downregulation of VPAC2-R by siRNA completely blocked cAMP response mediated by PACAP and VIP. Importantly, PACAP/VIP as well as forskolin markedly suppressed the induction of alkaline phosphatase mRNA upon differentiation and the pretreatment with 2',5'-dideoxyadenosine, a cAMP inhibitor, restored its inhibitory effect of PACAP. We also found that PACAP and VIP stimulated IL-6 release, a stimulator of bone resorption, and VPAC2-R silencing inhibited IL-6 production. Thus, PACAP/VIP can activate adenylate cyclase response and regulate IL-6 release through VPAC2 receptor with profound functional consequences for the inhibition of osteoblastic differentiation in MC3T3-E1 cells.
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Affiliation(s)
- Azusa Nagata
- Department of Clinical Cell Biology, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba-shi, Chiba, Japan
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12
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Wilson LA, Wayman CP, Jackson VM. Neuropeptide modulation of a lumbar spinal reflex: potential implications for female sexual function. J Sex Med 2009; 6:947-957. [PMID: 19170864 DOI: 10.1111/j.1743-6109.2008.01150.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Neuropeptides are known to modulate female receptivity. However, even though receptivity is a spinal reflex, the role of neuropeptides within the spinal cord remains to be elucidated. AIM The aims were to (i) investigate neuropeptides in the lumbosacral region; and (ii) determine how neuropeptides modulate glutamate release from stretch Ia fibers, touch sensation Abeta fibers and Adelta/C pain fibers. MAIN OUTCOME MEASURES Neuropeptide modulation of the lumbosacral dorsal-root ventral-root reflex in vitro. METHODS Spinal cords were removed from Sprague-Dawley rats in compliance with UK Home Office guidelines. Hemisected cords were superfused with aCSF and the dorsal root (L4-S1) was stimulated to evoke glutamate release. A biphasic reflex response was evoked from the opposite ventral root consisting of a monosynaptic (Ia fibers) and polysynaptic (Abeta, Adelta/C fibers) component. RESULTS The micro opioid receptor (MOR) agonist DAMGO inhibited the monosynaptic (EC(50) 0.02 +/- 0.02 nM) and polysynaptic area (EC(50) 125 +/- 167 nM) but not polysynaptic amplitude. Oxytocin and corticotrophin releasing factor (CRF) inhibited the monosynaptic amplitude (EC(50), 1.4 +/- 1.0 nM and EC(50) 4.3 +/- 3.5 nM, respectively), polysynaptic amplitude (EC(50) 18.2 +/- 28.0 nM and EC(50), 9.5 +/- 13.3 nM, respectively), and area (EC(50) 11.6 +/- 13.0 nM and EC(50), 2.8 +/- 3.3 nM, respectively); effects that were abolished by oxytocin and CRF(1) antagonists, L-368899 and 8w. Melanocortin agonists solely inhibited the monosynaptic component, which were blocked by the MC(3/4) receptor antagonist SHU9119. CONCLUSION These data suggest endogenous neuropeptides are released within the lumbosacral spinal cord. Melanocortin agonists, oxytocin, CRF, and DAMGO via MC(4), oxytocin, CRF(1), and MOR inhibit glutamate release but with differing effects on afferent fiber subtypes. Melanocortins, oxytocin, CRF, and DAMGO have the ability to modulate orgasm whereas oxytocin, CRF and DAMGO can increase pain threshold. Oxytocin and CRF may dampen touch sensation.
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Affiliation(s)
- Lesley A Wilson
- Pfizer Global Research & Development-Discovery Biology, Sandwich, Kent, UK
| | - Chris P Wayman
- Pfizer Global Research & Development-Discovery Biology, Sandwich, Kent, UK
| | - V Margaret Jackson
- Pfizer Global Research & Development-Discovery Biology, Sandwich, Kent, UK.
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Sándor K, Bölcskei K, McDougall JJ, Schuelert N, Reglődi D, Elekes K, Pethő G, Pintér E, Szolcsányi J, Helyes Z. Divergent peripheral effects of pituitary adenylate cyclase-activating polypeptide-38 on nociception in rats and mice. Pain 2009; 141:143-50. [DOI: 10.1016/j.pain.2008.10.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 10/11/2008] [Accepted: 10/30/2008] [Indexed: 01/11/2023]
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Yoshiyama M, de Groat WC. Effects of intrathecal administration of pituitary adenylate cyclase activating polypeptide on lower urinary tract functions in rats with intact or transected spinal cords. Exp Neurol 2008; 211:449-55. [PMID: 18410926 DOI: 10.1016/j.expneurol.2008.02.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2007] [Revised: 01/31/2008] [Accepted: 02/20/2008] [Indexed: 11/24/2022]
Abstract
Effects of intrathecally administered pituitary adenylate cyclase activating polypeptide-38 (PACAP-38, 0.1-30 microg) on lower urinary tract function were examined in unanesthetized, decerebrate rats with an intact spinal cord and after chronic spinal cord transection (SCT). PACAP-38 was also studied in rats with intact or bilaterally transected hypogastric nerves (HGNs), to determine if sympathetic pathways to the bladder influenced responses. In SCT rats with intact HGNs under isovolumetric conditions, 30 mug of PACAP-38 but not lower doses (0.1-10 microg) increased (mean 194%) bladder contraction amplitude (BCA). In SCT rats with sectioned HGNs, 10 microg and 30 microg of PACAP-38 increased BCA by 62% and 195%, respectively. On the other hand, during continuous infusion cystometrograms (CMGs) in SCT rats with intact or sectioned HGNs, PACAP-38 (10 microg and 30 microg) markedly reduced or completely suppressed BCA (60% and 90%, respectively) and reduced external urethral sphincter (EUS) EMG activity (58% and 91%, respectively). During CMGs in spinal cord intact rats, with intact HGNs PACAP-38 30 microg increased BCA (26%) but after HGN section PACAP-38 10 microg and 30 microg increased BCA by 21% and 35%. These results suggest that after SCT, PACAP-38 activates spinal circuitry to facilitate the parasympathetic outflow to the urinary bladder and that the elimination of sympathetic pathways enhances this effect. The decrease in BCA by PACAP-38 during CMGs in SCT rats is most reasonably attributed to a reduction in urethral outlet resistance due to suppression of excitatory EUS reflexes.
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Affiliation(s)
- Mitsuharu Yoshiyama
- Yamanashi Rehabilitation Hospital, 855 Komatsu, Kasugai-Cho, Fuefuki, Yamanashi, 406-0004, Japan.
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Staines DR. Is gulf war syndrome an autoimmune disorder of endogenous neuropeptides, exogenous sandfly maxadilan and molecular mimicry? Med Hypotheses 2004; 62:658-64. [PMID: 15082085 DOI: 10.1016/j.mehy.2004.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2004] [Accepted: 01/11/2004] [Indexed: 12/21/2022]
Abstract
Gulf War Syndrome (GWS) remains a contentious diagnosis with conflicting laboratory investigation and lack of a biologically plausible aetiology. This paper discusses the potential role of maxadilan, a potent sandfly vasoactive peptide, in causing autoimmune responses in susceptible individuals through possible molecular mimicry with pituitary adenylate cyclase activating polypeptide (PACAP) and the PAC1R receptor. Gulf War Syndrome may share some causative pathology with Chronic Fatigue Syndrome (CFS), a disorder characterised by prolonged fatigue and debility mostly associated with post-infection sequelae although ongoing infection is unproven. Immunological aberration associated with an expanding group of vasoactive neuropeptides in the context of molecular mimicry and inappropriate immunological memory has been recently raised as possible cause of CFS. Vasoactive neuropeptides act as hormones, neurotransmitters, immune modulators and neurotrophes. They are readily catalysed to small peptide fragments. They and their binding sites are immunogenic and are known to be associated with a range of autoimmune conditions. Maxadilan, while not sharing substantial sequence homology with PACAP is a known agonist of the PACAP specific receptor (PAC1R) and therefore emulates these functions. Moreover a specific amino acid sequence peptide deletion within maxadilan converts it to a PACAP receptor antagonist raising the possibility of this substance provoking a CFS like response in humans exposed to it. This paper describes a biologically plausible mechanism for the development of a GWS-like chronic fatigue state based on loss of immunological tolerance to the vasoactive neuropeptide PACAP or its receptor following bites of the sandfly Phlebotomus papatasi and injection of the vasodilator peptide maxadilan. Exacerbation of this autoimmune response as a consequence of recent or simultaneous multiple vaccination exposures deserves further investigation. While the possible association between the relatively recently discovered vasoactive neuropeptides and chronic fatigue conditions has only recently been reported in the literature, this paper explores links for further research into GWS and CFS.
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Affiliation(s)
- Donald R Staines
- Gold Coast Public Health Unit, 10-12 Young Street, Southport, Qld. 4215, Australia.
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Yamamoto T, Nozaki-Taguchi N, Chiba T. Analgesic effect of intrathecally administered orexin-A in the rat formalin test and in the rat hot plate test. Br J Pharmacol 2002; 137:170-6. [PMID: 12208773 PMCID: PMC1573477 DOI: 10.1038/sj.bjp.0704851] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Orexin-A and orexin-B (also known as hypocretin-1 and hypocretin-2) are hypothalamic peptides and regulate feeding behaviour, energy metabolism and the sleep-wake cycle. Orexin-A binds equally to both orexin-1 and orexin-2 receptors, while orexin-B has a preferential affinity for orexin-2 receptors. 2. Orexins are also known to be concentrated in superficial laminae of the spinal dorsal horn, and orexin-A and orexin-1 receptors are found in the dorsal root ganglion cells. 3. In the present study, the authors examined the effect of intrathecal injection of either orexin-A or orexin-B in the rat formalin test (a model of inflammatory pain) and in the rat hot plate test. The paw formalin injection induces biphasic flinching (phase 1: 0-6 min; phase 2: 10-60 min) of the injected paw. 4. Intrathecal injection of orexin-A, but not orexin-B, decreased the sum of flinches in phases 1 and 2 in the formalin test and increased the hot plate latency. These effects of orexin-A were completely antagonized by pre-treatment with SB-334867, a selective orexin-1 receptor antagonist. Intrathecal injection of SB-334867 alone had no effect in the formalin test or in the hot plate test. 5. Intrathecal injection of orexin-A suppressed the expression of Fos-like immunoreactivity (Fos-LI), induced by paw formalin injection, in laminae I-II of L4-5 of the spinal cord. 6. These data suggest that the spinal orexin-1 receptor is involved in the nociceptive transmission and that the activation of the spinal orexin-1 receptor produces analgesic effects in the rat formalin test and in the rat hot plate test.
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Affiliation(s)
- Tatsuo Yamamoto
- Department of Anesthesiology, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba-shi, Chiba 260-8677, Japan.
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