Mice deficient in pituitary adenylate cyclase activating polypeptide display increased sensitivity to renal oxidative stress in vitro

Systematic investigation of the multi-scale mechanisms of herbal medicine on treating ventricular remodeling: Theoretical and experimental studies

BACKGROUND

To explore the underlying molecule mechanism of herbal medicine in preventing ventricular remodeling (VR), we take a herbal formula that is clinically effective for preventing VR as an example, which composed of Pachyma hoelen Rumph, Atractylodes macrocephala Koidz., Cassia Twig and Licorice. Due to multi-components and multi-targets in herbal medicine, it is extremely difficult to systematically explain its mechanisms of action.

METHODS

An innovative systematic investigation framework which combines with pharmacokinetic screening, target fishing, network pharmacology, DeepDDI algorithm, computational chemistry, molecular thermodynamics, in vivo and in vitro experiments was performed for deciphering the underlying molecular mechanisms of herbal medicine for treating VR.

RESULTS

ADME screening and SysDT algorithm determined 75 potentially active compounds and 109 corresponding targets. Then, systematic analysis of networks reveals the crucial active ingredients and key targets in herbal medicine. Additionally, transcriptomic analysis identifies 33 key regulators during VR progression. Moreover, PPI network and biological function enrichment present four crucial signaling pathways, i.e. NF-κB and TNF, PI3K-AKT and C-type lectin receptor signaling pathways involved in VR. Besides, both molecular experiments at animal and cell levels reveal the beneficial effect of herbal medicine on preventing VR. Finally, MD simulations and binding free energy validate the reliability of drug-target interactions.

CONCLUSION

Our novelty is to build a systematic strategy which combines various theoretical methods combined with experimental approaches. This strategy provides a deep understanding for the study of molecular mechanisms of herbal medicine on treating diseases from systematic level, and offers a new idea for modern medicine to explore drug interventions for complex diseases as well.

Effects of Pituitary Adenylate Cyclase Activating Polypeptide on Cell Death

Pituitary adenylate cyclase activating polypeptide (PACAP) was first isolated as a hypothalamic peptide based on its efficacy to increase adenylate cyclase (AC) activity. It has a widespread distribution throughout the body including the nervous system and peripheral organs, where PACAP exerts protective effects both in vivo and in vitro through its anti-apoptotic, anti-inflammatory, and antioxidant functions. The aim of the present paper was to review the currently available literature regarding the effects of PACAP on cell death in vitro in neural and non-neural cells. Among others, its effect on apoptosis can be detected in cerebellar granule cells against different toxic stimuli. Different neural cell types from the cerebral cortex are also prevented from cell death. PACAP also shows effects on cell death in cells belonging to the peripheral nervous system and protects both neural and non-neural cells of sensory organs. In addition, cell survival-promoting effect can be observed in different peripheral organ systems including cardiovascular, immune, respiratory, gastrointestinal, urinary, and reproductive systems. The studies summarized here indicate its noteworthy effect on cell death in different in vitro models, suggesting PACAP’s potential therapeutic usage in several pathological conditions.

Protective Effects of PACAP in Peripheral Organs

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide widely distributed in the nervous system, where it exerts strong neuroprotective effects. PACAP is also expressed in peripheral organs but its peripheral protective effects have not been summarized so far. Therefore, the aim of the present paper is to review the existing literature regarding the cytoprotective effects of PACAP in non-neuronal cell types, peripheral tissues, and organs. Among others, PACAP has widespread expression in the digestive system, where it shows protective effects in various intestinal pathologies, such as duodenal ulcer, small bowel ischemia, and intestinal inflammation. PACAP is present in both the exocrine and endocrine pancreas as well as liver where it reduces inflammation and steatosis by interfering with hepatic pathology related to obesity. It is found in several exocrine glands and also in urinary organs, where, with its protective effects being mainly published regarding renal pathologies, PACAP is protective in numerous conditions. PACAP displays anti-inflammatory effects in upper and lower airways of the respiratory system. In the skin, it is involved in the development of inflammatory pathology such as psoriasis and also has anti-allergic effects in a model of contact dermatitis. In the non-neuronal part of the visual system, PACAP showed protective effects in pathological conditions of the cornea and retinal pigment epithelial cells. The positive role of PACAP has been demonstrated on the formation and healing processes of cartilage and bone where it also prevents osteoarthritis and rheumatoid arthritis development. The protective role of PACAP was also demonstrated in the cardiovascular system in different pathological processes including hyperglycaemia-induced endothelial dysfunction and age-related vascular changes. In the heart, PACAP protects against ischemia, oxidative stress, and cardiomyopathies. PACAP is also involved in the protection against the development of pre-senile systemic amyloidosis, which is presented in various peripheral organs in PACAP-deficient mice. The studies summarized here provide strong evidence for the cytoprotective effects of the peptide. The survival-promoting effects of PACAP depend on a number of factors which are also shortly discussed in the present review.

The Neuropeptide Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) is Protective in Inflammation and Oxidative Stress-Induced Damage in the Kidney

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic neuropeptide with a widespread distribution throughout the entire body including the urinary system. PACAP exerts protective actions in different injury models related to several organ systems. Its protective effect is mainly based on its antiapoptotic, anti-inflammatory and antioxidant effects. The present review aims to summarize the effects of PACAP in pathologies associated with inflammation and oxidative stress-induced damage in the kidney. Both in vitro and in vivo data are available proving its protective actions against oxidative stress, hypoxia, renal ischemia/reperfusion, diabetic nephropathy, myeloma kidney injury, amyloidosis and different types of drug-induced nephropathies. Data showing the nephroprotection by PACAP emphasize the potential of PACAP’s therapeutic use in various renal pathologies.

PACAP deficiency as a model of aging

Dysregulation of neuropeptides may play an important role in aging-induced impairments. In the long list of neuropeptides, pituitary adenylate cyclase-activating polypeptide (PACAP) represents a highly effective cytoprotective peptide that provides an endogenous control against a variety of tissue-damaging stimuli. PACAP has neuro- and general cytoprotective effects due to anti-apoptotic, anti-inflammatory, and antioxidant actions. As PACAP is also a part of the endogenous protective machinery, it can be hypothesized that the decreased protective effects in lack of endogenous PACAP would accelerate age-related degeneration and PACAP knockout mice would display age-related degenerative signs earlier. Recent results support this hypothesis showing that PACAP deficiency mimics aspects of age-related pathophysiological changes including increased neuronal vulnerability and systemic degeneration accompanied by increased apoptosis, oxidative stress, and inflammation. Decrease in PACAP expression has been shown in different species from invertebrates to humans. PACAP-deficient mice display numerous pathological alterations mimicking early aging, such as retinal changes, corneal keratinization and blurring, and systemic amyloidosis. In the present review, we summarize these findings and propose that PACAP deficiency could be a good model of premature aging.

Effects of pituitary adenylate cyclase activating polypeptide on small intestinal INT 407 cells

Pituitary adenylate cyclase activating polypeptide (PACAP) is an endogenous neuropeptide having a widespread distribution both in the nervous system and peripheral organs including the gastrointestinal tract. It has been shown to exert actions on intestinal functions, mainly affecting glandular secretion and motility. PACAP has several different effects on cell survival depending on the cell type and the applied stimulus. Its influences on small intestinal epithelial cells are not yet elucidated, therefore the aim of the present study was to investigate the effects of PACAP on intestinal epithelial cells having high turnover (INT 407) against different harmful stimuli, such as oxidative stress, in vitro hypoxia and gamma radiation. We tested the effect of PACAP on proliferation and cell survival using MTT assay. Moreover, various cancer-related factors were evaluated by oncology array. PACAP did not influence the proliferation rate of INT 407 cells. Its cell survival-enhancing effect could be detected against oxidative stress, but not against in vitro hypoxia or gamma irradiation. Clonogenic survival assay was performed to analyze the effect of PACAP on clonogenic potential of cells exposed to gamma radiation. Surprisingly, PACAP enhanced the clone-forming ability decrease induced by irradiation. Western blot analysis of ERK1/2 phosphorylation was performed in order to obtain further information on the molecular background. Our data showed phospho-ERK1/2 suppression of PACAP in irradiated cells. Furthermore, the role of endogenous PACAP against oxidative stress was also investigated performing ADCYAP1 small interfering RNA transfection. We found significant difference in the cell vulnerability between cells undergoing silencing and cells without transfection suggesting the protective role of the endogenously present PACAP against oxidative stress in INT 407 cells. In summary, PACAP seems to be able to exert contradictory effects in INT 407 cells depending on the applied stressor, suggesting its regulatory role in the cellular household.

Ischemia/reperfusion-induced Kidney Injury in Heterozygous PACAP-deficient Mice

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide with very diverse distribution and functions. Among others, PACAP is a potent cytoprotective peptide due to its antiapoptotic, anti-inflammatory, and antioxidant actions. This also has been shown in different kidney pathologies, including ischemia/reperfusion-induced kidney injury. Similar protective effects of the endogenous PACAP are confirmed by the increased vulnerability of PACAP-deficient mice to different harmful stimuli. Kidneys of homozygous PACAP-deficient mice have more severe damages in renal ischemia/reperfusion and kidney cell cultures isolated from these mice show increased sensitivity to renal oxidative stress. In our present study we raised the question of whether the partial lack of the PACAP gene is also deleterious, i.e. whether heterozygous PACAP-deficient mice also display more severe damage after renal ischemia/reperfusion. Mice underwent 45 or 60 minutes of ischemia followed by 2 weeks reperfusion. Histological evaluation of the kidneys was performed and individual histopathological parameters were graded. Furthermore, we investigated apoptotic markers, cytokine expression, and the activity of superoxide dismutase (SOD) enzyme 24 hours after 60 minutes of renal ischemia/reperfusion. We found no difference between the intact kidneys of wild-type and heterozygous mice, but marked differences could be observed following ischemia/reperfusion. Heterozygous PACAP-deficient mice had more severe histological alterations, with significantly higher histopathological scores for most of the tested parameters. Higher level of the proapoptotic pp38 MAPK and of some proinflammatory cytokines, as well as lower activity of the antioxidant SOD could be found in these mice. In conclusion, the partial lack of the PACAP gene results in worse outcomes in cases of renal ischemia/reperfusion, confirming that PACAP functions as an endogenous protective factor in the kidney.

The effects of pituitary adenylate cyclase activating polypeptide in renal ischemia/reperfusion

Pituitary adenylate cyclase activating polypeptide (PACAP ) is a multifunctional neuropeptide occurring in the nervous system as well as in the peripheral organs. Beneficial action of PACAP has been shown in different pathological processes. The strong protective effects of the peptide are probably due to its complex modulatory actions in antiapoptotic, anti-inflammatory and antioxidant pathways. In the kidney, PACAP is protective in models of diabetic nephropathy, myeloma kidney injury, cisplatin-, gentamycin- and cyclosporin-induced damages. Numerous studies have been published describing the protective effect of this peptide in renal ischemia/reperfusion. The present review focuses on the ischemia/reperfusion-induced kidney injury and gives a brief summary about the results published in this area.

Comparative protein composition of the brains of PACAP-deficient mice using mass spectrometry-based proteomic analysis

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a widespread neuropeptide acting as a neurotransmitter, neuromodulator, or neurotrophic factor. The diverse biological actions provide the background for the variety of deficits observed in mice lacking endogenous PACAP. PACAP-deficient mice display several abnormalities, such as sudden infant death syndrome (SIDS)-like phenotype, decreased cell protection, and increased risk of Parkinson's disease. However, the molecular and proteomic background is still unclear. Therefore, our aim was to investigate the differences in peptide and protein composition in the brains of PACAP-deficient and wild-type mice using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometric (MS)-based proteomic analysis. Brains from PACAP-deficient mice were removed, and different brain areas (cortex, hippocampus, diencephalon, mesencephalon, brainstem, and cerebellum) were separated. Brain pieces were weighed, homogenized, and further processed for electrophoretic analysis. Our results revealed several differences in diencephalon and mesencephalon. The protein bands of interest were cut from the gel, samples were digested with trypsin, and the tryptic peptides were measured by matrix-assisted laser desorption ionization time of flight (MALDI TOF) MS. Results were analyzed by MASCOT Search Engine. Among the altered proteins, several are involved in metabolic processes, energy homeostasis, and structural integrity. ATP-synthase and tubulin beta-2A were expressed more strongly in PACAP-knockout mice. In contrast, the expression of more peptides/proteins markedly decreased in knockout mice, like pyruvate kinase, fructose biphosphate aldolase-A, glutathione S-transferase, peptidyl propyl cis-trans isomerase-A, gamma enolase, and aspartate amino transferase. The altered expression of these enzymes might partially account for the decreased antioxidant and detoxifying capacity of PACAP-deficient mice accompanying the increased vulnerability of these animals. Our results provide novel insight into the altered biochemical processes in mice lacking endogenous PACAP.

Pituitary adenylate cyclase activating polypeptide (PACAP) signalling exerts chondrogenesis promoting and protecting effects: implication of calcineurin as a downstream target

Pituitary adenylate cyclase activating polypeptide (PACAP) is an important neurotrophic factor influencing differentiation of neuronal elements and exerting protecting role during traumatic injuries or inflammatory processes of the central nervous system. Although increasing evidence is available on its presence and protecting function in various peripheral tissues, little is known about the role of PACAP in formation of skeletal components. To this end, we aimed to map elements of PACAP signalling in developing cartilage under physiological conditions and during oxidative stress. mRNAs of PACAP and its receptors (PAC1,VPAC1, VPAC2) were detectable during differentiation of chicken limb bud-derived chondrogenic cells in micromass cell cultures. Expression of PAC1 protein showed a peak on days of final commitment of chondrogenic cells. Administration of either the PAC1 receptor agonist PACAP 1-38, or PACAP 6-38 that is generally used as a PAC1 antagonist, augmented cartilage formation, stimulated cell proliferation and enhanced PAC1 and Sox9 protein expression. Both variants of PACAP elevated the protein expression and activity of the Ca-calmodulin dependent Ser/Thr protein phosphatase calcineurin. Application of PACAPs failed to rescue cartilage formation when the activity of calcineurin was pharmacologically inhibited with cyclosporine A. Moreover, exogenous PACAPs prevented diminishing of cartilage formation and decrease of calcineurin activity during oxidative stress. As an unexpected phenomenon, PACAP 6-38 elicited similar effects to those of PACAP 1-38, although to a different extent. On the basis of the above results, we propose calcineurin as a downstream target of PACAP signalling in differentiating chondrocytes either in normal or pathophysiological conditions. Our observations imply the therapeutical perspective that PACAP can be applied as a natural agent that may have protecting effect during joint inflammation and/or may promote cartilage regeneration during degenerative diseases of articular cartilage.

[Examination of cytoprotective and anti-inflammatory effect of PACAP-38 on small bowel autotransplantation]

INTRODUCTION

The small intestine is one of the most sensitive organs to ischemia-reperfusion injury during transplantation. Cytoprotective effect of pituitary adenylate cyclase-activating polypeptide (PACAP) is well known. The aim of our study was to measure changes of PACAP-38-like immunoreactivities and cytokine levels in intestinal grafts stored PACAP-38 containing preservation solution.

MATERIAL AND METHODS

Small-bowel autotransplantation was performed on male Wistar rats (n = 56). Grafts were stored in University of Wisconsin (UW) solution at 4 °C for 1 (GI), 3 (GII), and 6 hours (GIII); and in PACAP-38 containing UW solution for 1 (GIV), 3 (GV), and 6 hours (GVI). Reperfusion lasted 3 hours in each group. Intestinal PACAP-38 immunoreactivities were measured by radioimmunoassay. To measure cytokine from tissue homogenates we used rat cytokine array and Luminex Multiplex Immunoassay.

RESULTS

Levels of PACAP-38-like and PACAP-27-like immunoreactivities decreased by preservation time compared to control. This decrease was significant following 6 hours cold storage (p < 0.05). Values remained significantly higher in grafts stored in PACAP-38 containing UW. Expressions of sICAM-1, L-selectin, tissue inhibitor of metalloproteinase-1 were increased in GIII and were decreased in GVI.

CONCLUSION

PACAP-38 increased tissue levels of PACAP-38 and PACAP-27, and decreased cytokine expression. This indicates that PACAP-38 has anti-inflammatory and cytoprotective effects in intestinal autotransplantation model.

Changes of PACAP immunoreactivities and cytokine levels after PACAP-38 containing intestinal preservation and autotransplantation

Small bowel is one of the most sensitive organs to ischemia-reperfusion injury, which is a significant problem during transplantation. Pituitary adenylate cyclase-activating polypeptide (PACAP) has cytoprotective effect in ischemic injuries of various tissues. The aim of our study was to measure changes of PACAP-38 and PACAP-27 immunoreactivities and cytokine levels in intestinal grafts stored in PACAP-38-containing preservation solution. Small bowel autotransplantation was performed on male Wistar rats. Grafts were stored in University of Wisconsin (UW) solution at 4 °C for 1 h (group (G)I), for 3 h (GII), and for 6 h (GIII) and in PACAP-38-containing UW solution for 1 h (GIV), for 3 h (GV), and for 6 h (GVI). After preservation, performing vessel anastomosis reperfusion began, which lasted 3 h in each group. Tissue biopsies were collected after laparotomy (control) and at the end of the reperfusion periods. Intestinal PACAP-38 and PACAP-27 immunoreactivities were measured by radioimmunoassay. To measure cytokines from tissue homogenates, we used rat cytokine array and Luminex Multiplex Immunoassay. Levels of PACAP-38 and PACAP-27 immunoreactivity decreased after 1 and 3 h preservation compared to control levels. This decrease was significant following 6 h cold storage (p < 0.05). Values remained significantly higher in grafts stored in PACAP-38-containing UW. Cytokine array revealed that expression of the soluble intercellular adhesion molecule-1 (CD54) and L-selectin (CD62L/LECAM-1) was increased in GIII. Both 6 h cold storage in PACAP-38-containing UW solution and 3 h reperfusion caused strong reduction in these cytokines activation in GVI. RANTES (CCL5) levels were increased in all groups. Strong activation of the tissue inhibitor of metalloproteinase-1 was in GIII. However, PACAP-38-containing cold storage could decrease its activation in GVI. Furthermore, strong activation of the tissue inhibitor of metalloproteinase-1 was detected in 6 h preserved grafts without PACAP-38 (GIII). PACAP-38-containing cold storage could decrease its activation in GVI. Our present study showed that PACAP-38 and PACAP-27 immunoreactivities decreased in a time-dependent manner during intestinal cold preservation, which could be ameliorated by administration of exogenous PACAP-38 to the preservation solution. Moreover, PACAP-38 could attenuate tissue cold ischemic injury-induced changes in cytokine expression.

Effects of pituitary adenylate cyclase activating polypeptide in the urinary system, with special emphasis on its protective effects in the kidney

Pituitary adenylate cyclase activating polypeptide (PACAP) is a widespread neuropeptide with diverse effects in the nervous system and peripheral organs. One of the most well-studied effects of PACAP is its cytoprotective action, against different harmful stimuli in a wide variety of cells and tissues. PACAP occurs in the urinary system, from the kidney to the lower urinary tract. The present review focuses on the nephroprotective effects of PACAP and summarizes data obtained regarding the protective effects of PACAP in different models of kidney pathologies. In vitro data show that PACAP protects tubular cells against oxidative stress, myeloma light chain, cisplatin, cyclosporine-A and hypoxia. In vivo data provide evidence for its protective effects in ischemia/reperfusion, cisplatin, cyclosporine-A, myeloma kidney injury, diabetic nephropathy and gentamicin-induced kidney damage. Results accumulated on the renoprotective effects of PACAP suggest that PACAP is an emerging candidate for treatment of human kidney pathologies.

Mice deficient in pituitary adenylate cyclase activating polypeptide (PACAP) show increased susceptibility to in vivo renal ischemia/reperfusion injury

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide with well-known cytoprotective effects. We have reported earlier that PACAP decreases mortality and the degree of tubular atrophy in a rat model of renal ischemia/reperfusion injury. Recently, we have shown that kidney cultures isolated from PACAP deficient mice show increased susceptibility to renal oxidative stress. Based on these previous studies, we raised the question whether PACAP deficient mice display increased sensitivity to in vivo kidney ischemia/reperfusion. PACAP⁻/⁻ mice underwent 45 or 60 min of renal ischemia followed by 2 weeks reperfusion. Kidneys were processed for histological analysis. Sections stained with PAS-haematoxylin were graded for the following parameters: degree of tubular dilation, Bowmann's capsule dilation, lymphocyte and macrophage infiltration, thyroidization and the disappearance of the PAS-positive glycocalyx from under the brush border. In other sets of experiments, tissue cytokine expression and the level of the endogenous antioxidant superoxide dismutase (SOD) were also determined after 60 min ischemia/reperfusion. Our results show that while intact kidneys were not different between wild-type and PACAP deficient mice, marked differences were observed in the histological structures in groups that underwent ischemia/reperfusion. PACAP deficient mice had a worse histological outcome, with significantly higher histological scores for all tested parameters. Cytokine expression was also markedly different between wild-type and PACAP deficient mice. In addition, the level of SOD was significantly lower in PACAP⁻/⁻ animals after ischemia/reperfusion. In conclusion, the lack of endogenous PACAP leads to higher susceptibility to in vivo renal ischemia/reperfusion, suggesting that PACAP has an endogenous renoprotective effect.

VIP and PACAP: recent insights into their functions/roles in physiology and disease from molecular and genetic studies

PURPOSE OF REVIEW

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) as well as the three classes of G-protein-coupled receptors mediating their effects, are widely distributed in the central nervous system (CNS) and peripheral tissues. These peptides are reported to have many effects in different tissues, which are physiological or pharmacological, and which receptor mediates which effect, has been difficult to determine, primarily due to lack of potent, stable, selective agonists/antagonists. Recently the use of animals with targeted knockout of the peptide or a specific receptor has provided important insights into their role in normal physiology and disease states.

RECENT FINDINGS

During the review period, considerable progress and insights has occurred in the understanding of the role of VIP/PACAP as well as their receptors in a number of different disorders/areas. Particularly, insights into their roles in energy metabolism, glucose regulation, various gastrointestinal processes including gastrointestinal inflammatory conditions and motility and their role in the CNS as well as CNS diseases has greatly expanded.

SUMMARY

PACAP/VIP as well as their three classes of receptors are important in many physiological/pathophysiological processes, some of which are identified in these studies using knockout animals. These studies may lead to new novel treatment approaches. Particularly important are their roles in glucose metabolism and on islets leading to possible novel approaches in diabetes; their novel anti-inflammatory, cytoprotective effects, their CNS neuroprotective effects, and their possible roles in diseases such as schizophrenia and chronic depression.

Effects of PACAP on oxidative stress-induced cell death in rat kidney and human hepatocyte cells

Oxidative stress plays an important role in various renal and hepatic pathologies, and reduction of oxidative stress-induced processes is an important protective strategy in tissues of diverse origins against harmful stimuli. Pituitary adenylate cyclase activating polypeptide (PACAP) is a well-known cytotrophic and cytoprotective peptide. PACAP promotes cell survival in numerous cells and tissues exposed to various stimuli. Protective effects of PACAP have been shown in the kidney, but it is not known whether PACAP is protective against oxidative stress in renal cells. Little is known about the effects of PACAP in the liver. The aim of the present study was to investigate whether PACAP is protective against oxidative stress in primary rat kidney cell culture and whether PACAP has any effect on cell survival in human WRL-68 hepatocytes and HEP-G2 hepatocellular carcinoma cells subjected to oxidative stress. Cells were exposed to various concentrations of H(2)O(2) with or without PACAP co-treatment and cell viability was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide test (MTT). We found that oxidative stress induced a significant decrease in cell viability in both cell lines. PACAP could dose-dependently increase the percentage of living cells in kidney cells, but it failed to do so in hepatocytes. Given the survival-promoting effects of PACAP against oxidative stress in rat kidney, we conducted a further experiment to determine whether PACAP influences the markers of oxidative stress in vivo. We have proven earlier that PACAP was effective in kidney ischemia/reperfusion injury in vivo. In the present study, we determined the levels of the oxidative stress marker malondialdehyde and the activity of the scavenger molecules glutathione (GSH) and superoxide dismutase (SOD) following kidney ischemia/reperfusion in rats. We found that PACAP significantly increased the level of GSH and counteracted the marked reduction of SOD activity after ischemia/reperfusion in vivo. In summary, the present study showed that while PACAP was able to significantly increase the cell survival in primary kidney cell cultures exposed to oxidative stress, possibly involving interaction with the endogenous scavenger system, it failed to influence the viability of normal or cancerous hepatocytes.

Effects of PACAP on mitochondrial apoptotic pathways and cytokine expression in rats subjected to renal ischemia/reperfusion

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide with highly efficient cytoprotective actions. Its neuroprotective effects are well-known, but PACAP is able to exert similar actions in non-neuronal cells. Recently, we have shown that PACAP prolongs renal ischemic time, decreases mortality, and attenuates tubular degeneration in a rat model of renal ischemia/reperfusion, but the mechanism of renoprotection is not yet known. Therefore, the aim of the present study was to obtain further insight into the renoprotective effects of PACAP by examining its direct effects of PACAP on mitochondrial permeability transition in vitro and on the expression of the anti-apoptotic Bcl-2 and cytokines/chemokines in kidney tissues following 45 and 60 min renal ischemia and reperfusion in vivo. We found that PACAP did not have any direct effect on mitochondrial permeability transition. Cytokine array revealed that the expression of a few cytokines/chemokines was strongly increased after ischemia/reperfusion, which was ameliorated by PACAP treatment. Furthermore, in rats subjected to renal ischemia, PACAP treatment counteracted the ischemia/reperfusion-induced decrease of the anti-apoptotic Bcl-2, both after 45 and 60 min ischemia, as analyzed by Western blot. In summary, we showed that PACAP could attenuate tissue injury involving both anti-inflammatory and anti-apoptotic effects, but not directly acting on mitochondrial permeability transition.