Pituitary Adenylate Cyclase-activating Polypeptide Levels Research Articles

Examination of pituitary adenylate cyclase-activating polypeptide (PACAP) in patients with atrial fibrillation undergoing pulmonary vein isolation

Abstract Introduction Pituitary adenylate cyclase-activating polypeptide (PACAP) is a cardioprotective neuropeptide. It has previously been shown that plazma PACAP level increases in myocardial infarction and decompensated heart failure, whereas it decreases in chronic heart failure. Patient material and method We examined blood samples from patients (n=46) undergoing pulmonary vein isolation for atrial fibrillation. We collected 5 ml blood samples from the femoral vein at the beginning, from the right atrium before the septal puncture, from the left atrium before and after the ablation, from the femoral vein at the end of the procedure and the next day from the cubital vein. PACAP levels were determined by ELISA. Patients were divided into intact (n=29) and scarred (n=17) left atrial groups by electroanatomical map. PACAP levels were compared in the total population and in the two groups and correlated with left atrial size and different comorbidity data. Results Significantly higher levels of PACAP were detected in atrial blood and in post-operative femoral vein samples compared to peripheral blood collected at the beginning and 1 day after the procedure. We measured decreased PACAP levels in the left atrium after ablation compared to samples from left atrium before the ablation. Although we found lower PACAP levels in the left atrium after ablation in patients with scarred atrium compared to the intact group, the PACAP levels showed significant elevation in the femoral vein after the ablation in patients with intact atria. Conclusions Our study was the first to show a difference between PACAP levels in atrial and peripheral blood samples. The elevated PACAP levels measured in atrial samples may be due to myocytes and neurons, whose PACAP production decreases depending on the degree of scarring following ablation-induced injury in the left atrium. Transient systemic elevation of PACAP levels is demonstrated in the periphery, suggesting a potential biomarker role for PACAP in these pathologies.

Pleural mesothelioma from fluoro-edenite exposure: PACAP and PAC1 receptor. A preliminary report.

Pleural mesothelioma is a devastating malignancy primarily associated with asbestos exposure. However, emerging evidence suggests that exposure to fluoro-edenite fibers, a naturally occurring mineral fiber, can also lead to the development of pleural mesothelioma. In this study, based on the hypothesis that pituitary adenylate cyclase-activating polypeptide (PACAP) and PACAP-preferring receptor (PAC1R) expressions could be dysregulated in pleural mesothelioma samples and that they could potentially act as diagnostic or prognostic biomarkers, we aimed to investigate the immunohistochemical expression of PACAP and PAC1R in pleural biopsies from patients with pleural mesothelioma exposed to fluoro-edenite fibers. A total of 12 patients were included in this study, and their biopsies were processed for immunohistochemical analysis to evaluate the expression of PACAP and its receptor. The study revealed a correlation between the overexpression of PACAP and PAC1R and shorter overall survival in patients with malignant mesothelioma. These findings suggest that PACAP and PAC1R expression levels could serve as potential prognostic biomarkers for malignant mesothelioma. Furthermore, the immunohistochemical analysis of PACAP and PAC1R may provide valuable information for clinicians to guide therapeutic decisions and identify patients with poorer prognosis.

Blood serum levels of PACAP and migraine onset: A systematic review and meta-analysis of observational studies.

We conducted a systematic review and meta-analysis to explore the relationship between blood pituitary adenylate cyclase-activating polypeptide (PACAP) levels and migraine. PACAP is involved in the onset of migraine, but the results from clinical studies on PACAP level variations across different periods of migraine are conflicting. We systematically searched for observational studies that reported PACAP levels in people with migraine and non-migraine controls published in English from the PubMed, Web of Science, and Ovid electronic databases, or in Chinese from the Chinese National Knowledge Infrastructure and the WanFang Med database. The Newcastle-Ottawa Quality Assessment Scale was used to assess the quality of the included studies. The quality of evidence for each outcome was assessed according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines. Of the 514 identified studies, 8 were eligible for inclusion. There was a "very low" level of evidence suggesting that the PACAP level is negatively correlated with migraine disease duration in adults with migraine (summary = -0.35, 95% confidence interval [CI] -0.49 to -0.22) and that the PACAP is higher in people with migraine during the ictal period than in the interictal period (standardized mean difference = 0.41, 95% CI 0.17 to 0.66) for both adults and children with migraine. Adult patients with episodic migraine (weighted mean difference [WMD] = -9.58 pg/mL, 95% CI -13.41 to -5.75 pg/mL) or chronic migraine (WMD = -10.93 pg/mL, 95% CI -15.57 to -6.29 pg/mL) had lower blood PACAP levels than non-migraine controls during the interictal period, supported by a "low" or "very low" quality of evidence, respectively, according to the GRADE rules. There is a very low certainty of evidence suggesting that the PACAP level is negatively correlated with migraine disease duration of adults with migraine and it varies greatly among different periods of migraine of both adults and children with migraine.

Effects of the Neuropeptides Pituitary Adenylate Cyclase Activating Polypeptide and Vasoactive Intestinal Peptide in Male Fertility.

Background and Objectives: The neuroendocrine system plays a crucial role in regulating various bodily functions, including reproduction, with evidence suggesting its significant involvement in male fertility and sperm development. Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) are expressed in both male and female reproductive tissues, influencing penile erection and regulating steroidogenesis in males. Therefore, our study aimed to compare the protein levels of VIP and PACAP in seminal plasma between healthy controls and sub-fertile patients. Additionally, we sought to correlate the levels of these biomarkers with clinical, functional, and laboratory findings in the participants. Materials and Methods: The study included a total of 163 male participants for analysis. The participants were further stratified into subgroups of fertile and sub-fertile men of four subgroups according to the 2021 WHO guidelines. Seminal plasma concentrations of the neuropeptides VIP and PACAP were measured using human enzyme-linked immunosorbent assay technique. Results: The findings showed statistically significant differences in total sperm count, sperm concentration, total motility, and vitality (p < 0.001) between the fertile group and the sub-fertile group. Specifically, significant differences found between healthy males and oligoasthenospermic patients (p = 0.002), and between asthenospermic and oligoasthenospermic patients (p = 0.039). An ROC analysis showed associated sensitivity and specificity values of 62.2% and 55.6%, respectively, to PACAP seminal levels differentiated between sub-fertile patients from fertile males (p = 0.028). No significant difference in seminal levels of VIP was found between the sub-fertile and fertile groups. Conclusions: Previous research leads to the point of PACAP active involvement in spermatogenesis. In accordance to our study, in human semen samples, we have seen a significance change in PACAP levels amongst patients with low sperm count or with both low sperm count and low motility, hinting at its contribution and acting as a possible factor in this complex process. Thus, alterations in the levels or actions of these neuropeptides have been associated with certain reproductive disorders in males.

Circulating PACAP levels are associated with altered imaging measures of entorhinal cortex neurite density in posttraumatic stress disorder.

Introduction: Pituitary adenylate cyclase-activating polypeptide (PACAP) regulates plasticity in brain systems underlying arousal and memory and is associated with posttraumatic stress disorder (PTSD). Research in animal models suggests that PACAP modulates entorhinal cortex (EC) input to the hippocampus, contributing to impaired contextual fear conditioning. In PTSD, PACAP is associated with higher activity of the amygdala to threat stimuli and lower functional connectivity of the amygdala and hippocampus. However, PACAP-affiliated structural alterations of these regions have not been investigated in PTSD. Here, we examined whether peripheral PACAP levels were associated with neuronal morphology of the amygdala and hippocampus (primary analyses), and EC (secondary) using Neurite Orientation Dispersion and Density Imaging.Methods: Sixty-four (44 female) adults (19 to 54 years old) with DSM-5 Criterion A trauma exposure completed the Clinician-Administered PTSD Scale (CAPS-5), a blood draw, and magnetic resonance imaging. PACAP38 radioimmunoassay was performed and T1-weighted and multi-shell diffusion-weighted images were acquired. Neurite Density Index (NDI) and Orientation Dispersion Index (ODI) were quantified in the amygdala, hippocampus, and EC. CAPS-5 total score and anxious arousal score were used to test for clinical associations with brain structure.Results: Higher PACAP levels were associated with greater EC NDI (β = 0.0099, q = 0.032) and lower EC ODI (β = -0.0073, q = 0.047), and not hippocampal or amygdala measures. Neither EC NDI nor ODI was associated with clinical measures.Conclusions: Circulating PACAP levels were associated with altered neuronal density of the EC but not the hippocampus or amygdala. These findings strengthen evidence that PACAP may impact arousal-associated memory circuits in PTSD.

The Role of Biomarkers Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and Vasoactive Intestinal Peptide (VIP) in Chronic and Episodic Migraines: A Meta-Analysis

Background. Migraine is a neurological disorder that results in disability accumulation, and there are no blood-based markers for indicating migraine susceptibility. Here, we aimed to evaluate the possible biomarker role of neuropeptides, vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating polypeptide (PACAP) in chronic (CM) and episodic migraine (EM). Method. PubMed, medRxiv, and Google Scholar databases were searched up to the 7th of September 2022 using the search syntax to define all relevant articles addressing the plasma and serum levels of VIP and PACAP in migraineurs and controls. Concerning bias assessment, the risk of bias in nonrandomized studies-I (ROBINS-I) was assessed. Also, the standardized mean difference (SMD) was measured with a random effects model. Results. Five case-control studies with 503 migraine cases were included. CM patients had elevated VIP levels compared to controls (SMD=0.44, 95% CI 0.25-0.62, p&lt;0.00001). In contrast, PACAP levels were lower in EM patients (SMD=−0.30, 95% CI -0.48 to -0.11, p=0.002). Overall, migraine cases had higher VIP levels (SMD=0.25, 95% CI 0.11-0.39, p=0.0006) but lower PACAP levels (SMD=−0.16, 95% CI -0.30 to -0.03, p=0.020) than controls. Conclusion. The results support the role of VIP and PACAP neuropeptides in migraine pathophysiology. CM patients have significantly higher serum VIP levels, while EM patients have lower serum PACAP levels compared to controls. Further studies should confirm these findings.

Development of a New Enzyme-Linked Immunosorbent Assay (ELISA) for Measuring the Content of PACAP in Mammalian Tissue and Plasma.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a naturally occurring neuropeptide found in both the central and peripheral nervous systems of vertebrates. Recent studies have revealed the presence of PACAP and its corresponding receptors, namely, the pituitary adenylate cyclase-activating polypeptide type I receptor (PAC1R), vasoactive intestinal peptide receptor 1 (VIPR1), and vasoactive intestinal peptide receptor 2 (VIPR2), in various structures implicated in migraine pathophysiology, including sensory trigeminal neurons. Human studies have demonstrated that when infused, PACAP can cause dilation of cranial vessels and result in delayed migraine-like attacks. In light of this, we present a novel ELISA assay that has been validated for quantifying PACAP in tissue extracts and human plasma. Using two well characterized antibodies specifically targeting PACAP, we successfully developed a sandwich ELISA assay, capable of detecting and accurately quantifying PACAP without any cross-reactivity to closely related peptides. The quantification range was between 5.2 pmol/L and 400 pmol/L. The recovery in plasma ranged from 98.2% to 100%. The increasing evidence pointing to the crucial role of PACAP in migraine pathophysiology necessitates the availability of tools capable of detecting changes in the circulatory levels of PACAP and its potential application as a reliable biomarker.

Increased pituitary adenylate cyclase-activating polypeptide in the central bed nucleus of the stria terminalis in mood disorders in men

The mood disorders major depressive disorder (MDD) and bipolar disorder (BD) are highly prevalent worldwide. Women are more vulnerable to these psychopathologies than men. The bed nucleus of the stria terminalis (BNST), the amygdala, and the hypothalamus are the crucial interconnected structures involved in the stress response. In mood disorders, stress systems in the brain are put into a higher gear. The BNST is implicated in mood, anxiety, and depression. The stress-related neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is highly abundant in the central BNST (cBNST). In this study, we investigated alterations in PACAP in the cBNST of patients with mood disorders. Immunohistochemical (IHC) staining of PACAP and in situ hybridization (ISH) of PACAP mRNA were performed on the cBNST of post-mortem human brain samples. Quantitative IHC revealed elevated PACAP levels in the cBNST in both mood disorders, MDD and BD, but only in men, not in women. The PACAP ISH was negative, indicating that PACAP is not produced in the cBNST. The results support the possibility that PACAP innervation of the cBNST plays a role in mood disorder pathophysiology in men.

Circulating PACAP levels are associated with increased amygdala-default mode network resting-state connectivity in posttraumatic stress disorder

The pituitary adenylate cyclase-activating polypeptide (PACAP) system is implicated in posttraumatic stress disorder (PTSD) and related amygdala-mediated arousal and threat reactivity. PTSD is characterized by increased amygdala reactivity to threat and, more recently, aberrant intrinsic connectivity of the amygdala with large-scale resting state networks, specifically the default mode network (DMN). While the influence of PACAP on amygdala reactivity has been described, its association with intrinsic amygdala connectivity remains unknown. To fill this gap, we examined functional connectivity of resting-state functional magnetic resonance imaging (fMRI) in eighty-nine trauma-exposed adults (69 female) screened for PTSD symptoms to examine the association between blood-borne (circulating) PACAP levels and amygdala-DMN connectivity. Higher circulating PACAP levels were associated with increased amygdala connectivity with posterior DMN regions, including the posterior cingulate cortex/precuneus (PCC/Precun) and left angular gyrus (lANG). Consistent with prior work, this effect was seen in female, but not male, participants and the centromedial, but not basolateral, subregions of the amygdala. Clinical association analyses linked amygdala-PCC/Precun connectivity to anxious arousal symptoms, specifically exaggerated startle response. Taken together, our findings converge with previously demonstrated effects of PACAP on amygdala activity in PTSD-related processes and offer novel evidence for an association between PACAP and intrinsic amygdala connectivity patterns in PTSD. Moreover, these data provide preliminary evidence to motivate future work ascertaining the sex- and subregion-specificity of these effects. Such findings may enable novel mechanistic insights into neural circuit dysfunction in PTSD and how the PACAP system confers risk through a disruption of intrinsic resting-state network dynamics.

Research on the mechanism of prednisone in the treatment of ITP via VIP/PACAP-mediated intestinal immune dysfunction

RationaleImmune thrombocytopenia (ITP) is thought to be a result of immune dysfunction, which is treated by glucocorticoids such as prednisone. Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) have immunomodulatory properties, but their role in intestinal immune control is unclear. The major goal of this study was to look at the effects of prednisone on platelet, VIP, and PACAP levels in ITP mice, as well as the regulatory system that controls intestinal immunity.MethodsEighteen BALB/c mice were randomly divided into three groups: blank control group, model control group, and prednisone group, with six mice in each group. The ITP animal model control group and the prednisone group were injected with anti-platelet serum (APS) to replicate the ITP animal model. The prednisone group began prednisone intervention on the 8th day. Platelet count was dynamically measured before APS injection, on the 4th day of injection, on the 1st day of administration, on the 4th day of administration, and at the end of the experiment. After the experiment, the expression of p53 protein in mouse mesenteric lymph node lymphocytes was detected by immunohistochemistry. The changes in lymphocyte apoptosis rate in mouse mesenteric lymph nodes were detected by in situ terminal transferase labeling (TUNEL). The contents of VIP and PACAP in the mouse brain, colon, and serum were detected by enzyme-linked immunosorbent assay (ELISA). The contents of IFN-γ, IL-4, IL-10, IL-17A in the mouse spleen were detected by ELISA.Results①Changes of peripheral platelet count: there was no significant difference in platelet count among the three groups before modeling; on the 4th day, the platelet count decreased in the model control group and prednisone group; on the 8th day, the number of platelets in model control group and prednisone group was at the lowest level; on the 12th day, the platelet count in prednisone group recovered significantly; on the 15th day, the platelet count in prednisone group continued to rise. ②Changes of VIP, PACAP: compared with the blank control group, VIP and PACAP in the model control group decreased significantly in the brain, colon, and serum. Compared with the model control group, the levels of VIP and PACAP in the brain, colon, and serum in the prednisone group were increased except for serum PACAP. ③Changes of mesenteric lymphocytes: the expression of p53 protein in the mesenteric lymph nodes of model control group mice was significantly higher than that of blank control group mice. After prednisone intervention, the expression of p53 protein decreased significantly.④Changes of cytokines in spleen: compared with blank control group, IFN- γ, IL-17A increased and IL-4 and IL-10 decreased in model control group. After prednisone intervention, IFN- γ, IL-17A was down-regulated and IL-4 and IL-10 were upregulated.ConclusionsPrednisone-upregulated VIP and PACAP levels decreased P53 protein expression and apoptosis rate in mesenteric lymph node lymphocytes and affected cytokine expression in ITP model mice. Therefore, we speculate that the regulation of intestinal immune function may be a potential mechanism of prednisone in treating ITP.

High plasma calcitonin gene-related peptide and serum pituitary adenylate cyclase-activating polypeptide levels in patients with neuropathic pain

IntroductionBased on animal studies, calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are thought to play a role in neurobiological events such as neuropathic pain, neuroprotection, neurotransmission, neural plasticity, and neurotrophic effects. The aim of the study is to investigate whether there is a change in the blood level of CGRP and PACAP in patients with neuropathic pain and to look for clues about the utility of these peptides as pharmacological targets in the treatment of neuropathic pain in humans. MethodsThe study included 60 polyneuropathy patients with neuropathic pain, 30 polyneuropathy patients without neuropathic pain (NNP) and 29 healthy subjects as control group. Polyneuropathy patients with neuropathic pain were divided into two groups as diabetic (D-PNP) and non-diabetic polyneuropathy (ND-PNP) patients. Plasma CGRP and serum PACAP levels were measured from venous blood samples of the patients and healthy controls. ResultsThe CGRP level was significantly higher in the D-PNP and ND-PNP groups compared to the control and NNP groups (P<0.05). PACAP levels were significantly higher in the D-PNP and ND-PNP groups compared to the control and NNP groups (P<0.05). There was no significant correlation between CGRP and PACAP levels and neuropathic pain scale (NPS). ConclusionsThis study is the first to demonstrate elevated plasma CGRP and serum PACAP levels in polyneuropathy patients with neuropathic pain. The results of this study are important in terms of showing that both CGRP and PACAP can be new pharmacological targets in the treatment of neuropathic pain and polyneuropathy in humans.

Novel Small Molecule Positive Allosteric Modulator SPAM1 Triggers the Nuclear Translocation of PAC1-R to Exert Neuroprotective Effects through Neuron-Restrictive Silencer Factor.

The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) exerts effective neuroprotective activity through its specific receptor, PAC1-R. We accidentally discovered that as a positive allosteric modulator (PAM) of PAC1-R, the small-molecule PAM (SPAM1) has a hydrazide-like structure, but different binding characteristics, from hydrazide for the N-terminal extracellular domain of PAC1-R (PAC1-R-EC1). SPAM1 had a significant neuroprotective effect against oxidative stress, both in a cell model treated with hydrogen peroxide (H2O2) and an aging mouse model induced by D-galactose (D-gal). SPAM1 was found to block the decrease in PACAP levels in brain tissues induced by D-gal and significantly induced the nuclear translocation of PAC1-R in PAC1R-CHO cells and mouse retinal ganglion cells. Nuclear PAC1-R was subjected to fragmentation and the nuclear 35 kDa, but not the 15 kDa fragments, of PAC1-R interacted with SP1 to upregulate the expression of Huntingtin (Htt), which then exerted a neuroprotective effect by attenuating the binding availability of the neuron-restrictive silencer factor (NRSF) to the neuron-restrictive silencer element (NRSE). This resulted in an upregulation of the expression of NRSF-related neuropeptides, including PACAP, the brain-derived neurotrophic factor (BDNF), tyrosine hydroxylase (TH), and synapsin-1 (SYN1). The novel mechanism reported in this study indicates that SPAM1 has potential use as a drug, as it exerts a neuroprotective effect by regulating NRSF.

Female reproductive functions of the neuropeptide PACAP.

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide originally isolated as a hypothalamic peptide. It has a widespread distribution in the body and has a diverse spectrum of actions. Among other processes, PACAP has been shown to be involved in reproduction. In this review we summarize findings related to the entire spectrum of female reproduction. PACAP is a regulatory factor in gonadal hormone production, influences follicular development and plays a role in fertilization and embryonic/placental development. Furthermore, PACAP is involved in hormonal changes during and after birth and affects maternal behavior. Although most data come from cell cultures and animal experiments, increasing number of evidence suggests that similar effects of PACAP can be found in humans. Among other instances, PACAP levels show changes in the serum during pregnancy and birth. PACAP is also present in the human follicular and amniotic fluids and in the milk. Levels of PACAP in follicular fluid correlate with the number of retrieved oocytes in hyperstimulated women. Human milk contains very high levels of PACAP compared to plasma levels, with colostrum showing the highest concentration, remaining steady thereafter for the first 7 months of lactation. All these data imply that PACAP has important functions in reproduction both under physiological and pathological conditions.

The Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) System of the Central Amygdala Mediates the Detrimental Effects of Chronic Social Defeat Stress in Rats.

Many psychiatric diseases stem from an inability to cope with stressful events, as chronic stressors can precipitate or exacerbate psychopathologies. The neurobiological mechanisms underlying the response to chronic stress and the resulting anxiety states remain poorly understood. Stress neuropeptides in the extended amygdala circuitry mediate the behavioral response to stress, and hyperactivity of these systems has been hypothesized to be responsible for the emergence of persistent negative outcomes and for the pathogenesis of anxiety-related and trauma-related disorders. Pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptor PAC1R are highly expressed within the central amygdala (CeA) and play a key role in stress regulation. Here, we used chronic social defeat stress (CSDS), a clinically relevant model of psychosocial stress that produces robust maladaptive behaviors in rodents. We found that 10 days of CSDS cause a significant increase in PACAP levels selectively in the CeA of rats, as well as an increase in PAC1R mRNA. Using a viral vector strategy, we found that PAC1R knock-down in the CeA attenuates the CSDS-induced body weight loss and prevents the CSDS-induced increase in anxiety-like behavior. Notably, CSDS animals display reduced basal corticosterone (CORT) levels and PAC1R knock-down in CeA further reduce them. Finally, the CeA PAC1R knock-down blocks the increase in corticotropin-releasing factor (CRF) immunoreactivity induced by CSDS in CeA. Our findings support the notion that the persistent activation of the PACAP-PAC1R system in the CeA mediates the behavioral outcomes of chronic psychosocial stress independently of the hypothalamic-pituitary-adrenal axis, perhaps via the recruitment of the CRF system.

Xiongzhi Dilong decoction interferes with calcitonin gene-related peptide (CGRP)-induced migraine in rats through the CGRP/iNOS pathway

To evaluate the effects of Xiongzhi Dilong decoction (XZDLD) and its wind medicine on calcitonin gene-related peptide (CGRP)-induced migraine and explore the mechanism through the CGRP/inducible nitric oxide synthase (iNOS) pathway. Rats were divided into control, model, XZDLD, XZDLD (external wind), XZDLD (internal wind), and olcegepant groups. CGRP was injected into the dura mater to induce a migraine. The frequency of head scratching, cage climbing, and facial grooming was observed. The pain threshold, the levels of CGRP, pituitary adenylate cyclase activating polypeptide (PACAP), substance P (SP), and the plasma protein extravasation (PPE) ratio were measured. The phosphorylation levels of p38, extracellular signal-regulated kinase 1/2 (ERK1/2), and expression of iNOS were detected by western blot. Compared with the model group, the three modified XZDLD groups showed reduced frequency of head scratching and cage climbing in the first 30 min (all P < .05). Facial grooming frequency was reduced in XZDLD and XZDLD (external wind) groups ( P = .0003 and P = .0131, respectively). External wind medicine played a more important role in increasing mechanical pain threshold than internal wind medicine. Moreover, compared with the model group, the three modified XZDLD groups demonstrated reduced plasma levels of CGRP and PACAP (all P < .05). No difference in the SP level was observed among the six groups. XZDLD reduced PPE ratio. XZDLD and XZDLD (external wind) groups suppressed the CGRP/iNOS pathway by inhibiting the p-p38/p38 ratio and the expression of iNOS. No difference in pERK1/2/ERK1/2 ratio was detected among the six groups. XZDLD increases pain threshold, downregulates the expression of CGRP and PACAP, and reduces PPE ratio by inhibiting the CGRP/iNOS pathway. External wind medicine is more effective than internal one on improving facial grooming and head scratching, increasing the mechanical pain threshold, and inhibiting the expression of iNOS.

Delayed cerebral ischemia associated with surgery for pituitary macroadenomas that express elevated levels of PACAP

Delayed cerebral ischemia (DCI) and cerebral vasospasm (VS) are rare but serious post-operative complications after surgery for pituitary macroadenomas; the mechanism of which are poorly understood. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a vasoactive neuropeptide expressed in pituitary adenomas and may play a role in DCI/VS. The aim of this case-control study was to investigate the association between tumor expression of PACAP and DCI/VS following pituitary surgery. Tumor tissue from five patients with DCI/VS following pituitary surgery and nine matched controls were evaluated for PACAP expression by immunohistochemistry. Nuclear PACAP expression was significantly elevated in patients with DCI/VS following pituitary surgery compared to controls (0.396 ± 0.0.16 a.u. vs 0.093 ± 0.04 a.u, p < 0.0001). There was a positive linear relationship between nuclear PACAP expression and pre-operative tumor volume (r2 = 0.41, p < 0.02) with a significant difference in slopes between the DCI/VS group compared to controls (y = x(5.0 × 10−3), r2 = 0.76 vs y = x(7.4 × 10−4), r2 = 0.07, p < 0.05). Elevated levels of tumor PACAP expression is associated with DCI/VS following pituitary surgery and may have a role in tumor growth. PACAP signaling may play a role the development of DCI, but further studies are needed.

Seasonal changes in the expression of PACAP, VPAC1, VPAC2, PAC1 and testicular activity in the testis of the muskrat (Ondatra zibethicus).

Pituitary adenylate cyclase-activating polypeptide (PACAP) plays an important role in the steroidogenesis and spermatogenesis in the testis through its receptors PAC1, VPAC1 and VPAC2. In this study, we investigated the seasonal expressions of PACAP, PAC1, VPAC1, VPAC2, luteinizing hormone receptor (LHR), follicle stimulating hormone receptor (FSHR), steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD) and CYP17A1 in the testis of male muskrat during the breeding season and non-breeding season, respectively. Histologically, we observed the presence of Leydig cells, Sertoli cells and various types of germ cells in the testis during the breeding season, yet only Leydig cells, Sertoli cells, spermatogonia and primary spermatocyte during the non-breeding season. In addition, the immunohistochemical localizations of PACAP and VPAC1 were identified in the Leydig cells, spermatogonia and spermatozoa during the breeding season, while only in the Leydig cells and spermatogonia during the non-breeding season, and PAC1 and VPAC2 were localized in the Leydig cells in both seasons, among which LHR, StAR, 3β-HSD and CYP17A1 were also expressed. Meanwhile, the protein and mRNA expression levels of PACAP, PAC1, VPAC1, VPAC2, LHR, FSHR, StAR, 3β-HSD and CYP17A1 in the testis during the breeding season were significantly higher than those during the non-breeding season. These results suggested that PACAP is involved in the regulation of steroidogenesis and spermatogenesis via an endocrine, autocrine or paracrine manner in the testis of muskrat.

Positive allosteric regulation of PAC1-R up-regulates PAC1-R and its specific ligand PACAP.

PAC1-R is a recognized preferential receptor for the neuropeptide of pituitary adenylate cyclase-activating polypeptide (PACAP), which mediates neuroprotective and nerve regenerative activities of PACAP. In this study, we found that in both PAC1R-CHO cells with high expression of PAC1R-eGFP and retinal ganglion cells (RGC-5) with the natural expression of PAC1-R, oligo-peptide PACAP(28-38) and the positively charged arginine-rich penetrating peptide TAT, as positive allosteric modulators of PAC1-R, significantly trigger the nuclear translocation of PAC1-R. The chromatin immunoprecipitation (ChIP)-PCR results show that the nuclear translocated PAC1-R binds with the promoter regions of PAC1-R and its specific ligand PACAP. The up-regulated promoter activities of PAC1-R and PACAP induced by PACAP(28-38) or TAT are positively correlative with the increase of the expression levels of PAC1-R and PACAP. Moreover, the nuclear translocation of PAC1-R induced by PACAP(28-38) or TAT is significantly inhibited by the mutation of PAC1-R on Cys25 and the palmitoylation inhibitor 2-bromopalmitate. Meanwhile, the increase in both PAC1-R and PACAP levels and the neuroprotective activities of PACAP(28-38) and TAT in MPP-induced cell model of Parkinson ' s disease are synchronously inhibited by 2-bromopalmitate, which are positively correlated with the nuclear translocation of PAC1-R induced by PACAP(28-38) or TAT. Bioinformatics analysis and motif enrichment analysis following ChIP-sequencing show that the transcription factors including SP1, Zic2, GATA1, REST and YY1 may be recruited by nuclear PAC1-R and involved in regulating the promoter activities of PAC1-R and PACAP. ChIP-sequencing and related bioinformatics analysis show that the downstream target genes regulated by the nuclear PAC1-R are mostly involved in the process of cellular stress and related to neuroprotection, neuronal genesis and development.

Examination of pituitary adenylate cyclase-activating polypeptide in Parkinson’s disease focusing on correlations with motor symptoms

The neuroprotective effects of pituitary adenylate cyclase-activating polypeptide (PACAP) have been shown in numerous in vitro and in vivo models of Parkinson’s disease (PD) supporting the theory that PACAP could have an important role in the pathomechanism of the disorder affecting mostly older patients. Earlier studies found changes in PACAP levels in neurological disorders; therefore, the aim of our study was to examine PACAP in plasma samples of PD patients. Peptide levels were measured with ELISA and correlated with clinical parameters, age, stage of the disorder based on the Hoehn and Yahr (HY) scale, subtype of the disease, treatment, and specific scores measuring motor and non-motor symptoms, such as movement disorder society-unified Parkinson’s disease rating scale (MDS-UPDRS), Epworth sleepiness scale (ESS), Parkinson’s disease sleep scale (PDSS-2), and Beck depression inventory (BDI). Our results showed significantly decreased PACAP levels in PD patients without deep brain stimulation (DBS) therapy and in akinetic-rigid subtype; additionally we also observed a further decrease in the HY stage 3 and 4. Elevated PACAP levels were found in patients with DBS. There were no significant correlations between PACAP level with MDS-UPDRS, type of pharmacological treatment, PDSS-2 sleepiness, or depression (BDI) scales, but we found increased PACAP level in patients with more severe sleepiness problems based on the ESS scale. Based on these results, we suggest that following the alterations of PACAP with other frequently used clinical biomarkers in PD patients might improve strategic planning of further therapeutic interventions and help to provide a clearer prognosis regarding the future perspective of the disease.

PACAP and VIP Mitigate Rotenone-Induced Inflammation in BV-2 Microglial Cells

Rotenone is a commercial pesticide commonly used to model Parkinson’s disease (PD) due to its ability to induce dopaminergic degeneration. Studies have confirmed that rotenone causes microglial activation, which seems to contribute to the toxic effects seen in rodent models. Pituitary adenylate cyclase–activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two structurally related neuropeptides that have robust neuroprotective and anti-inflammatory properties. However, their ability to regulate microglial activity in response to rotenone is not fully understood. Using rotenone as an inflammatory stimulus, we tested whether PACAP or VIP could mitigate microglial activation in BV2 microglial cells. Rotenone dose-dependently reduced cell viability and the percentage of apoptotic cells. It also increased the release of nitric oxide (NO) in culture media and the expression of microglial activation markers and pro-inflammatory markers, including CD11b, MMP-9 and IL-6, and heightened the endogenous levels of PACAP and its preferring receptor PAC1. Co-treatment with PACAP or VIP prevented rotenone-induced increase of NO, CD11b, MMP-9 and IL-6. These results indicate that both PACAP and VIP are able to prevent the pro-inflammatory effects of rotenone in BV2 cells, supporting the idea that these molecules can have therapeutic value in slowing down PD progression.Graphical