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Background: Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 is an endogenous neuropeptide with diverse functions, notably its critical role in inhibiting tumor proliferation. Radiotherapy is an important step in the standard treatment modality of many tumors. Combining radiotherapy with therapeutic agents represents a new and promising trend aimed at enhancing radiation sensitivity and improving tumor treatment efficacy. However, the efficacy of PACAP38 combined with radiotherapy on tumors has not yet been studied. Objective: This study aimed to investigate the impact of PACAP38, both independently and in combination with irradiation, on glioma and breast cancer cells, while elucidating the underlying mechanisms involved. Methods: We investigated the impact of PACAP38 independently and combined it with irradiation on glioma and breast cancer cells in vitro through cell counting kit-8, clonogenic formation, Edu assays, and in vivo through a xenograft tumor model. We further explored the molecular mechanisms underlying the inhibitory effects of PACAP38 on tumors using RNA sequencing, western blotting assay, immunohistochemistry, and immunofluorescence analysis. Further investigation of gene function and the downstream mechanism was carried out through small interfering RNA and overexpression lentivirus targeting the SRY-related high-mobility group box 6 (SOX6) gene and western blotting assay. Results: Our findings revealed that PACAP38 could effectively synergize with radiation to suppress the proliferation of glioma and breast cancer cells in vivo and in vitro. Molecular studies revealed that the inhibitory effect of PACAP38 on tumor cell proliferation was mediated by upregulating SOX6 protein expression through histone acetylation, thereby inhibiting the Wnt-β-catenin signaling pathway. Conclusion: PACAP38 synergizes with irradiation to suppress the proliferation of multiple cancer cells via regulating SOX6/Wnt/β-catenin signaling. This combination may represent a promising therapeutic strategy for cancer treatment, potentially improving outcomes for patients undergoing radiotherapy. [ABSTRACT FROM AUTHOR]

BackgroundPituitary adenylate cyclase-activating polypeptide (PACAP) 38 is an endogenous neuropeptide with diverse functions, notably its critical role in inhibiting tumor proliferation. Radiotherapy is an important step in the standard treatment modality of many tumors. Combining radiotherapy with therapeutic agents represents a new and promising trend aimed at enhancing radiation sensitivity and improving tumor treatment efficacy. However, the efficacy of PACAP38 combined with radiotherapy on tumors has not yet been studied.ObjectiveThis study aimed to investigate the impact of PACAP38, both independently and in combination with irradiation, on glioma and breast cancer cells, while elucidating the underlying mechanisms involved.MethodsWe investigated the impact of PACAP38 independently and combined it with irradiation on glioma and breast cancer cells in vitro through cell counting kit-8, clonogenic formation, Edu assays, and in vivo through a xenograft tumor model. We further explored the molecular mechanisms underlying the inhibitory effects of PACAP38 on tumors using RNA sequencing, western blotting assay, immunohistochemistry, and immunofluorescence analysis. Further investigation of gene function and the downstream mechanism was carried out through small interfering RNA and overexpression lentivirus targeting the SRY-related high-mobility group box 6 (SOX6) gene and western blotting assay.ResultsOur findings revealed that PACAP38 could effectively synergize with radiation to suppress the proliferation of glioma and breast cancer cells in vivo and in vitro. Molecular studies revealed that the inhibitory effect of PACAP38 on tumor cell proliferation was mediated by upregulating SOX6 protein expression through histone acetylation, thereby inhibiting the Wnt-β-catenin signaling pathway.ConclusionPACAP38 synergizes with irradiation to suppress the proliferation of multiple cancer cells via regulating SOX6/Wnt/β-catenin signaling. This combination may represent a promising therapeutic strategy for cancer treatment, potentially improving outcomes for patients undergoing radiotherapy.

Abstract Background Pain, an evolutionarily conserved warning system, lets us recognize threats and motivates us to adapt to those threats. Headache pain from migraine affects approximately 15% of the global population. However, the identity of any putative threat that migraine or headache warns us to avoid is unknown because migraine pathogenesis is poorly understood. Here, we show that a stress-induced increase in pituitary adenylate cyclase-activating polypeptide-38 (PACAP38), known as an initiator of allosteric load inducing unbalanced homeostasis, causes headache-like behaviour in male mice via mas-related G protein-coupled receptor B2 (MrgprB2) in mast cells. Methods The repetitive stress model and dural injection of PACAP38 were performed to induce headache behaviours. We assessed headache behaviours using the facial von Frey test and the grimace scale in wild-type and MrgprB2-deficient mice. We further examined the activities of trigeminal ganglion neurons using in vivo Pirt-GCaMP Ca2+ imaging of intact trigeminal ganglion (TG). Results Repetitive stress and dural injection of PACAP38 induced MrgprB2-dependent headache behaviours. Blood levels of PACAP38 were increased after repetitive stress. PACAP38/MrgprB2-induced mast cell degranulation sensitizes the trigeminovascular system in dura mater. Moreover, using in vivo intact TG Pirt-GCaMP Ca2+ imaging, we show that stress or/and elevation of PACAP38 sensitized the TG neurons via MrgprB2. MrgprB2-deficient mice showed no sensitization of TG neurons or mast cell activation. We found that repetitive stress and dural injection of PACAP38 induced headache behaviour through TNF-a and TRPV1 pathways. Conclusions Our findings highlight the PACAP38-MrgprB2 pathway as a new target for the treatment of stress-related migraine headache. Furthermore, our results pertaining to stress interoception via the MrgprB2/PACAP38 axis suggests that migraine headache warns us of stress-induced homeostatic imbalance.

Background: Pain, an evolutionarily conserved warning system, lets us recognize threats and motivates us to adapt to those threats. Headache pain from migraine affects approximately 15% of the global population. However, the identity of any putative threat that migraine or headache warns us to avoid is unknown because migraine pathogenesis is poorly understood. Here, we show that a stress-induced increase in pituitary adenylate cyclase-activating polypeptide-38 (PACAP38), known as an initiator of allosteric load inducing unbalanced homeostasis, causes headache-like behaviour in male mice via mas-related G protein-coupled receptor B2 (MrgprB2) in mast cells. Methods: The repetitive stress model and dural injection of PACAP38 were performed to induce headache behaviours. We assessed headache behaviours using the facial von Frey test and the grimace scale in wild-type and MrgprB2-deficient mice. We further examined the activities of trigeminal ganglion neurons using in vivo Pirt-GCaMP Ca2+ imaging of intact trigeminal ganglion (TG). Results: Repetitive stress and dural injection of PACAP38 induced MrgprB2-dependent headache behaviours. Blood levels of PACAP38 were increased after repetitive stress. PACAP38/MrgprB2-induced mast cell degranulation sensitizes the trigeminovascular system in dura mater. Moreover, using in vivo intact TG Pirt-GCaMP Ca2+ imaging, we show that stress or/and elevation of PACAP38 sensitized the TG neurons via MrgprB2. MrgprB2-deficient mice showed no sensitization of TG neurons or mast cell activation. We found that repetitive stress and dural injection of PACAP38 induced headache behaviour through TNF-a and TRPV1 pathways. Conclusions: Our findings highlight the PACAP38-MrgprB2 pathway as a new target for the treatment of stress-related migraine headache. Furthermore, our results pertaining to stress interoception via the MrgprB2/PACAP38 axis suggests that migraine headache warns us of stress-induced homeostatic imbalance. [ABSTRACT FROM AUTHOR]

The degenerative retinal disorders characterized by progressive cell death and exacerbating inflammation lead ultimately to blindness. The ubiquitous neuropeptide, PACAP38 is a promising therapeutic agent as its proliferative potential and suppressive effect on microglia might enable cell replacement and attenuate inflammation, respectively. Our previous finding that PACAP38 caused a marked increase of the amacrine cells in the adult (1-year-old) mouse retina, served as a rationale of the current study. We aimed to determine the proliferating elements and the inflammatory status of the PACAP38-treated retina. Three months old mice were intravitreally injected with 100 pmol PACAP38 at 3 months intervals (3X). Retinas of 1-year-old animals were dissected and effects on cell proliferation, and expression of inflammatory regulators were analyzed. Interestingly, both mitogenic and anti-mitogenic actions were detected after PACAP38-treatment. Further analysis of the mitogenic effect revealed that proliferating cells include microglia, endothelial cells, and neurons of the ganglion cell layer but not amacrine cells. Furthermore, PACAP38 stimulated retinal microglia to polarize dominantly into M2-phenotype but also might cause subsequent angiogenesis. According to our results, PACAP38 might dampen pro-inflammatory responses and help tissue repair by reprogramming microglia into an M2 phenotype, nonetheless, with angiogenesis as a warning side effect. [ABSTRACT FROM AUTHOR]

Background: Pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) provoked cluster headache attacks in individuals with episodic cluster headache during their active phase and individuals with chronic cluster headache. In this study, we investigated whether infusions of PACAP and VIP caused alterations in plasma levels of VIP and their potential contribution to induced cluster headache attacks. Methods: Participants received either PACAP or VIP infusion for 20min on 2 separate days with an interval of at least 7 days in between. Blood collection was performed at T0, T20, T30, and T90. Plasma levels of VIP were measured using a validated radioimmunoassay method. Results: Blood samples were collected from participants with episodic cluster headache in the active phase (eCHA, n = 14), remission (eCHR, n = 15), and from participants with chronic cluster headache (cCH, n = 15). Baseline levels of VIP did not differ among the three groups (p = 0.1161). During PACAP infusion, mixed-effects analysis revealed a significant increase in plasma levels of VIP in eCHA (p = 0.0300) and eCHR (p = 0.0058) but not in cCH (p = 0.2930). We found no difference in the increase of plasma VIP levels between patients who developed PACAP38- or VIP-induced attacks. Conclusion: Cluster headache attacks induced by PACAP38 or VIP infusion are not associated with changes in plasma levels of VIP. Further studies are needed to investigate the role of VIP and the parasympathetic system in cluster headache. [ABSTRACT FROM AUTHOR]

BackgroundPituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) provoked cluster headache attacks in individuals with episodic cluster headache during their active phase and individuals with chronic cluster headache. In this study, we investigated whether infusions of PACAP and VIP caused alterations in plasma levels of VIP and their potential contribution to induced cluster headache attacks.MethodsParticipants received either PACAP or VIP infusion for 20 min on 2 separate days with an interval of at least 7 days in between. Blood collection was performed at T0, T20, T30, and T90. Plasma levels of VIP were measured using a validated radioimmunoassay method.ResultsBlood samples were collected from participants with episodic cluster headache in the active phase (eCHA, n = 14), remission (eCHR, n = 15), and from participants with chronic cluster headache (cCH, n = 15). Baseline levels of VIP did not differ among the three groups (p = 0.1161). During PACAP infusion, mixed-effects analysis revealed a significant increase in plasma levels of VIP in eCHA (p = 0.0300) and eCHR (p = 0.0058) but not in cCH (p = 0.2930). We found no difference in the increase of plasma VIP levels between patients who developed PACAP38- or VIP-induced attacks.ConclusionCluster headache attacks induced by PACAP38 or VIP infusion are not associated with changes in plasma levels of VIP. Further studies are needed to investigate the role of VIP and the parasympathetic system in cluster headache.Clinical trial registrationThe parent study is registered at ClinicalTrials.gov (NCT03814226).

The study aimed to understand mechanism/s of neuronal outgrowth in the rat adrenal-derived pheochromocytoma cell line (PC12) under pituitary adenylate cyclase-activating polypeptide (PACAP) treatment. Neurite projection elongation was suggested to be mediated via Pac1 receptor-mediated dephosphorylation of CRMP2, where GSK-3β, CDK5, and Rho/ROCK dephosphorylated CRMP2 within 3 h after addition of PACAP, but the dephosphorylation of CRMP2 by PACAP remained unclear. Thus, we attempted to identify the early factors in PACAP-induced neurite projection elongation via omics-based transcriptomic (whole genome DNA microarray) and proteomic (TMT-labeled liquid chromatography-tandem mass spectrometry) analyses of gene and protein expression profiles from 5–120 min after PACAP addition. The results revealed a number of key regulators involved in neurite outgrowth, including known ones, called 'Initial Early Factors', e.g., genes Inhba, Fst, Nr4a1,2,3, FAT4, Axin2, and proteins Mis12, Cdk13, Bcl91, CDC42, including categories of 'serotonergic synapse, neuropeptide and neurogenesis, and axon guidance'. cAMP signaling and PI3K-Akt signaling pathways and a calcium signaling pathway might be involved in CRMP2 dephosphorylation. Cross-referencing previous research, we tried to map these molecular components onto potential pathways, and we may provide important new information on molecular mechanisms of neuronal differentiation induced by PACAP. Gene and protein expression data are publicly available at NCBI GSE223333 and ProteomeXchange, identifier PXD039992. [ABSTRACT FROM AUTHOR]

Introduction: The activation of perivascular fibers and the consequent release of vasoactive peptides, including the vasoactive intestinal polypeptide (VIP), play a role in migraine pathogenesis. A 2-h infusion of VIP provoked migraine, but the mechanisms remain unknown. We investigated whether 2-h infusion of VIP caused alterations in plasma levels of the calcitonin gene-related peptide (CGRP) and whether any changes might be related to the induced migraine attacks. Materials and Methods: We enrolled individuals with episodic migraine without aura and healthy participants to randomly receive a 2-h infusion of either VIP (8 pmol/kg/min) or placebo (sterile saline) in two randomized, placebo-controlled crossover trials. We collected clinical data and measured plasma levels of VIP and CGRP at fixed time points: at baseline (T0) and every 30 min until 180 min (T180) after the start of the infusion. Results: Blood samples were collected from patients with migraine (n = 19) and healthy individuals (n = 12). During VIP infusion, mixed effects analysis revealed a significant increase in plasma CGRP (p = 0.027) at T30 (vs. T180, adjusted p- value = 0.039) and T60 (vs. T180, adjusted p -value = 0.027) in patients with migraine. We found no increase in plasma CGRP during VIP-induced migraine attacks (p = 0.219). In healthy individuals, there was no increase in plasma CGRP during VIP (p = 0.205) or placebo (p = 0.428) days. Discussion: Plasma CGRP was elevated in patients with migraine during a prolonged infusion of VIP, but these alterations were not associated with VIP-induced migraine attacks. Given the exploratory design of our study, further investigations are needed to clarify the role of CGRP in VIP-induced migraine. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT03989817 and NCT04260035. [ABSTRACT FROM AUTHOR]

IntroductionThe activation of perivascular fibers and the consequent release of vasoactive peptides, including the vasoactive intestinal polypeptide (VIP), play a role in migraine pathogenesis. A 2-h infusion of VIP provoked migraine, but the mechanisms remain unknown. We investigated whether 2-h infusion of VIP caused alterations in plasma levels of the calcitonin gene-related peptide (CGRP) and whether any changes might be related to the induced migraine attacks.Materials and MethodsWe enrolled individuals with episodic migraine without aura and healthy participants to randomly receive a 2-h infusion of either VIP (8 pmol/kg/min) or placebo (sterile saline) in two randomized, placebo-controlled crossover trials. We collected clinical data and measured plasma levels of VIP and CGRP at fixed time points: at baseline (T0) and every 30 min until 180 min (T180) after the start of the infusion.ResultsBlood samples were collected from patients with migraine (n = 19) and healthy individuals (n = 12). During VIP infusion, mixed effects analysis revealed a significant increase in plasma CGRP (p = 0.027) at T30 (vs. T180, adjusted p-value = 0.039) and T60 (vs. T180, adjusted p-value = 0.027) in patients with migraine. We found no increase in plasma CGRP during VIP-induced migraine attacks (p = 0.219). In healthy individuals, there was no increase in plasma CGRP during VIP (p = 0.205) or placebo (p = 0.428) days.DiscussionPlasma CGRP was elevated in patients with migraine during a prolonged infusion of VIP, but these alterations were not associated with VIP-induced migraine attacks. Given the exploratory design of our study, further investigations are needed to clarify the role of CGRP in VIP-induced migraine.Clinical Trial RegistrationClinicalTrials.gov, identifier: NCT03989817 and NCT04260035.

Abstract Background Pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) induces headache in healthy volunteers but the precise mechanisms by which PACAP38 leads to headache are unclear. We investigated the headache preventive effect of sumatriptan and ketorolac on PACAP38-induced headache in healthy volunteers. In addition, we explored contribution of vascular mechanisms to PACAP38-induced headache using high resolution magnetic resonance angiography. Methods Thirty-four healthy volunteers were divided in two groups (A and B) and received infusion of PACAP38 (10 picomol/kg/min) over 20 min. Group A was pretreated with intravenous sumatriptan (4 mg) or ketorolac (30 mg) 20 min before infusion of PACAP38. Group B received infusion of sumatriptan or ketorolac as post-treatment 90 min after infusion of PACAP38. In both experiments, we used a randomized, double-blind, cross-over design. We recorded headache characteristics and circumference of extra-intracerebral arteries. Results We found no difference in AUC (0–6 h) of PACAP38-induced headache in group A, pretreated with sumatriptan or ketorolac (p = 0.297). There was no difference between sumatriptan and ketorolac in PACAP38-induced circumference change (AUCBaseline-110 min) of MMA (p = 0.227), STA (p = 0.795) and MCA (p = 0.356). In group B, post-treatment with ketorolac reduced PACAP38-headache compared to sumatriptan (p

The study aimed to understand mechanism/s of neuronal outgrowth in the rat adrenal-derived pheochromocytoma cell line (PC12) under pituitary adenylate cyclase-activating polypeptide (PACAP) treatment. Neurite projection elongation was suggested to be mediated via Pac1 receptor-mediated dephosphorylation of CRMP2, where GSK-3β, CDK5, and Rho/ROCK dephosphorylated CRMP2 within 3 h after addition of PACAP, but the dephosphorylation of CRMP2 by PACAP remained unclear. Thus, we attempted to identify the early factors in PACAP-induced neurite projection elongation via omics-based transcriptomic (whole genome DNA microarray) and proteomic (TMT-labeled liquid chromatography-tandem mass spectrometry) analyses of gene and protein expression profiles from 5–120 min after PACAP addition. The results revealed a number of key regulators involved in neurite outgrowth, including known ones, called ‘Initial Early Factors’, e.g., genes Inhba, Fst, Nr4a1,2,3, FAT4, Axin2, and proteins Mis12, Cdk13, Bcl91, CDC42, including categories of ‘serotonergic synapse, neuropeptide and neurogenesis, and axon guidance’. cAMP signaling and PI3K-Akt signaling pathways and a calcium signaling pathway might be involved in CRMP2 dephosphorylation. Cross-referencing previous research, we tried to map these molecular components onto potential pathways, and we may provide important new information on molecular mechanisms of neuronal differentiation induced by PACAP. Gene and protein expression data are publicly available at NCBI GSE223333 and ProteomeXchange, identifier PXD039992.

Traumatic optic neuropathy (TON) refers to optic nerve damage caused by trauma, leading to partial or complete loss of vision. The primary treatment options, such as hormonal therapy and surgery, have limited efficacy. Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38), a functional endogenous neuroprotective peptide, has emerged as a promising therapeutic agent. In this study, we used rat retinal ganglion cell (RGC) exosomes as nanosized vesicles for the delivery of PACAP38 loaded via the exosomal anchor peptide CP05 (EXOPACAP38). EXOPACAP38 showed greater uptake efficiency in vitro and in vivo than PACAP38. The results showed that EXOPACAP38 significantly enhanced the RGC survival rate and retinal nerve fiber layer thickness in a rat TON model. Moreover, EXOPACAP38 significantly promoted axon regeneration and optic nerve function after injury. These findings indicate that EXOPACAP38 can be used as a treatment option and may have therapeutic implications for patients with TON.

Background: In recent years, vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptides (PACAPs) have gained special interest in headache science. VIP and PACAPs (two isoforms, PACAP27 and PACAP38) are related in structure and function, as are their receptors, but they show differences in vasodilating- and headache-inducing properties. Intravenous infusion of PACAP27 or PACAP38, but not VIP, induces a long-lasting dilation of cranial arteries and delayed headache. The relationship between the long-lasting cranial vasodilation and headache development is not fully clarified.Methods: In a double-blinded, placebo-controlled, crossover study in 12 healthy volunteers, diameter changes of cranial arteries, occurrence of headache and the parasympathetic system were examined before, during and after a 2-hour continuous intravenous infusion of VIP and placebo. Primary endpoints were the differences in area under the curve for the superficial temporal artery diameter and headache intensity scores, as well as in headache incidence, between VIP and placebo.Results: The superficial temporal artery diameter was significantly larger on the VIP day compared to placebo (p < 0.001) and the dilation lasted for more than 2 h. The incidence of headache was higher (p = 0.003) on the VIP day compared to the placebo day. The difference in headache intensity scores was more evident in the post-infusion period (120-200 min, p = 0.034) and in the post-hospital phase (4-12 h, p = 0.025). Cranial parasympathetic activity, measured through the production of tears, was higher during VIP compared to placebo (p = 0.033).Conclusion: Continuous intravenous infusion of VIP over 2 h induced a long-lasting cranial vasodilation, activation of the cranial parasympathetic system, and delayed mild headaches in healthy volunteers.Trial Registration: The study is registered at ClinicalTrials.gov (NCT03989817). [ABSTRACT FROM AUTHOR]

Background: Pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) induces headache in healthy volunteers but the precise mechanisms by which PACAP38 leads to headache are unclear. We investigated the headache preventive effect of sumatriptan and ketorolac on PACAP38-induced headache in healthy volunteers. In addition, we explored contribution of vascular mechanisms to PACAP38-induced headache using high resolution magnetic resonance angiography. Methods: Thirty-four healthy volunteers were divided in two groups (A and B) and received infusion of PACAP38 (10 picomol/kg/min) over 20 min. Group A was pretreated with intravenous sumatriptan (4 mg) or ketorolac (30 mg) 20 min before infusion of PACAP38. Group B received infusion of sumatriptan or ketorolac as post-treatment 90 min after infusion of PACAP38. In both experiments, we used a randomized, double-blind, cross-over design. We recorded headache characteristics and circumference of extra-intracerebral arteries. Results: We found no difference in AUC (0–6 h) of PACAP38-induced headache in group A, pretreated with sumatriptan or ketorolac (p = 0.297). There was no difference between sumatriptan and ketorolac in PACAP38-induced circumference change (AUCBaseline-110 min) of MMA (p = 0.227), STA (p = 0.795) and MCA (p = 0.356). In group B, post-treatment with ketorolac reduced PACAP38-headache compared to sumatriptan (p < 0.001). Post-treatment with sumatriptan significantly reduced the circumference of STA (p = 0.039) and MMA (p = 0.015) but not of MCA (p = 0.981) compared to ketorolac. In an explorative analysis, we found that pre-treatment with sumatriptan reduced PACAP38-induced headache compared to no treatment (AUC0-90min). Conclusions: Post-treatment with ketorolac was more effective in attenuating PACAP38-induced headache compared to sumatriptan. Ketorolac exerted its effect without affecting PACAP38-induced arterial dilation, whereas sumatriptan post-treatment attenuated PACAP38-induced dilation of MMA and STA. Pre-treatment with sumatriptan attenuated PACAP38-induced headache without affecting PACAP38-induced arterial dilation. Our findings suggest that ketorolac and sumatriptan attenuated PACAP38-induced headache in healthy volunteers without vascular effects. Trial registration: Clinicaltrials.gov (NCT03585894). Registered 13 July 2018, [ABSTRACT FROM AUTHOR]

Abstract Background To review the role of PACAP38 in human models of primary headaches, discuss possible mechanisms of PACAP38-induced migraine, and outline future directions. Discussion Experimental studies have established PACAP38 as a potent pharmacological “trigger” molecule of migraine-like attacks. These studies have also revealed a heterogeneous PACAP38 migraine response in migraine without aura patients. In addition, findings from brain imaging studies have demonstrated neuronal and vascular changes in migraine patients both ictally and interictally after PACAP38 infusion. Conclusion Human migraine models have shed light on the importance of PACAP38 in the pathophysiology of primary headaches. These studies have also pointed to the PAC1 receptor and the PACAP38 molecule itself as target sites for drug testing. Future research should seek to understand the mechanisms underlying PACAP38-induced migraine. The results from an ongoing proof of concept randomized clinical trial may reveal the therapeutic potential of anti-PAC1 receptor antibodies for migraine prevention.

• PACAP38 attenuated HDM-induced AHR in asthma. • PACAP38 reduced HDM-induced asthmatic airway inflammation. • PACAP38 decreased abnormal distribution of the AJC. • PACAP38 activated the cAMP/PKA signaling pathway. • PACAP38 improved airway inflammation and airway epithelial barrier damage. This study aimed to investigate the mechanism of PACAP38 on house dust mite (HDM)-induced asthmatic airway epithelial barrier destruction. The HDM-induced asthma mice model and 16HBE cell model was established respectively. The enzyme linked immunosorbent assay (ELSIA), cell count and immunohistochemical assay were performed on mice in control group, HDM group and PACAP38 + HDM group.The cAMP/PKA activity, p-CREB and total CREB expression, TEER and the FITC-DX were investigated on cells in control-16HBE group, HDM-16HBE group and PACAP38 + HDM-16HBE group. The levels of IL-4 and IL-5 in the HDM group were significantly higher than those in the control group (P < 0.05), while the above indexes in the PACAP38 + HDM group were lower than those in the HDM group (P < 0.05). E-cadherin, β-catenin, ZO-1 and occludin in the control group were highly immunoreactive in airway epithelial cells, whereas connexin staining was attenuated after HDM induction. The TEER level, cAMP levels and PKA activity were decreased, while FITC-DX transmittance was increased in HDM-16HBE group (P < 0.05) compared with the control-16HBE group. PACAP38 could reduce the airway inflammation, weaken the AJC protein heterotopia and activate cAMP/PKA signaling pathway in HDM-induced asthma, which indicate that PACAP38 may be an important contributor in HDM-induced asthma. [ABSTRACT FROM AUTHOR]

Objective: To investigate the role of calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) and vasoactive intestinal polypeptide in cluster headache, we measured these vasoactive peptides interictally and during experimentally induced cluster headache attacks.Methods: We included patients with episodic cluster headache in an active phase (n = 9), episodic cluster headache patients in remission (n = 9) and patients with chronic cluster headache (n = 13). Cluster headache attacks were induced by infusion of calcitonin gene-related peptide (1.5 µg/min) in a randomized, double-blind, placebo controlled, two-way cross-over study. At baseline, we collected interictal blood samples from all patients and during 11 calcitonin gene-related peptide-induced cluster headache attacks.Results: At baseline, episodic cluster headache patients in remission had higher plasma levels of calcitonin gene-related peptide, 100.6 ± 36.3 pmol/l, compared to chronic cluster headache patients, 65.9 ± 30.5 pmol/l, ( p = 0.011). Episodic cluster headache patients in active phase had higher PACAP38 levels, 4.0 ± 0.8 pmol/l, compared to chronic cluster headache patients, 3.3 ± 0.7 pmol/l, ( p = 0.033). Baseline levels of vasoactive intestinal polypeptide did not differ between cluster headache groups. We found no attack-related increase in calcitonin gene-related peptide, PACAP38 or vasoactive intestinal polypeptide levels during calcitonin gene-related peptide-induced cluster headache attacks.Conclusions: This study suggests that cluster headache disease activity is associated with alterations of calcitonin gene-related peptide expression. Future studies should investigate the potential of using calcitonin gene-related peptide measurements in monitoring of disease state and predicting response to preventive treatments, including response to anti-calcitonin gene-related peptide monoclonal antibodies. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of the H1-antihistamine clemastine on the migraine-inducing abilities of pituitary adenylate cyclase activating peptide-38.Methods: We conducted a double-blind, randomized, placebo controlled two-way cross-over study. Twenty migraine without aura patients were randomly allocated to receive bolus clemastine 2 mg (1 mg/ml) or bolus saline 2 ml intravenously over 2 min on two study days. Following each bolus injection, 10 pmol/kg/min of pituitary adenylate cyclase activating peptide-38 was administered intravenously over 20 min. We recorded migraine/headache characteristics every 10 min until 90 min after the start of infusion, and collected blood to investigate mast cell degranulation and the inflammation markers tryptase and tumor necrosis factor-alpha before and after infusion of pituitary adenylate cyclase activating peptide-38.Results: After clemastine pretreatment, five out of 20 participants developed a migraine-like attack in response to a pituitary adenylate cyclase activating peptide-38 infusion compared to nine out of 20 after placebo pretreatment ( p = 0.288). Following clemastine pretreatment, 15 out of 20 participants reported headache in response to a pituitary adenylate cyclase activating peptide-38 infusion, whereas 19 out of 20 participants did so following placebo pretreatment ( p = 0.221). We found no difference in area under the curve 12 h for headache intensity between the two experimental days ( p = 0.481). We found no difference in area under the curve 180 min for tryptase ( p = 0.525) or tumor necrosis factor-alpha ( p = 0.487) between clemastine and placebo pretreatment days.Conclusion: H1-antihistamine, clemastine, failed to prevent migraine or headache after pituitary adenylate cyclase activating peptide-38 infusion, thus making a role for histamine release or mast cell degranulation in pituitary adenylate cyclase activating peptide-38-induced migraine less likely. [ABSTRACT FROM AUTHOR]

Here, we review the role of pituitary adenylate cyclase-activating peptide-38 (PACAP38) in migraine pathophysiology and data implicating PAC1 receptor as a future drug target in migraine. Much remains to be fully elucidated about migraine pathophysiology, but recent attention has focused on signaling molecule PACAP38, a vasodilator able to induce migraine attacks in patients who experience migraine without aura. PACAP38, with marked and sustained effect, dilates extracerebral arteries but not the middle cerebral artery. The selective affinity of PACAP38 to the PAC1 receptor makes this receptor a highly interesting and potential novel target for migraine treatment. Efficacy of antagonism of this receptor should be investigated in randomized clinical trials. [ABSTRACT FROM AUTHOR]

Injuries to the central nervous system can affect the blood-brain barrier (BBB), including disruption and influencing peptide transport across the BBB. Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38) is a potent neurotrophic and neuroprotective peptide currently being investigated for its therapeutic role following injury to the central nervous system and can cross the BBB in a saturable manner. The goal of the current study was to investigate for the first time PACAP38 uptake by the brain following traumatic brain injury (TBI). Using radioactively labeled PACAP38, we measured the levels of PACAP38 present in the injured, ipsilateral cortex in Sham-treated mice compared to mice receiving a controlled cortical impact (CCI), a model of TBI. Experiments were conducted at 6 different time points (from 2 h up to 4 weeks) following CCI to determine temporal changes in PACAP38 transport. PACAP38 uptake was increased at 2 and 72 h post-CCI compared to Sham. We did not detect changes in PACAP38 uptake in the contralateral cortex and cerebellum between Sham and CCI-treatment. The rate of PACAP38 transport into the ipsilateral cortex following CCI was increased 3.6-fold 72 h after compared to 2 h post-CCI. In addition, the rate of transport into the cerebellum was greater than that of the cortices. The data presented here shows PACAP38 transport is temporally altered following CCI-treatment and PACAP38 uptake is greater in the cerebellum compared to the cortices. [ABSTRACT FROM AUTHOR]

Pituitary adenylate-cyclase activating polypeptide (PACAP) has neuroprotective and axonal guidance functions, but the mechanisms behind such actions remain unclear. Previously we examined effects of PACAP (PACAP38, 1 pmol) injection intracerebroventrically in a mouse model of permanent middle cerebral artery occlusion (PMCAO) along with control saline (0.9% NaCl) injection. Transcriptomic and proteomic approaches using ischemic (ipsilateral) brain hemisphere revealed differentially regulated genes and proteins by PACAP38 at 6 and 24 h post-treatment. However, as the ischemic hemisphere consisted of infarct core, penumbra, and non-ischemic regions, specificity of expression and localization of these identified molecular factors remained incomplete. This led us to devise a new experimental strategy wherein, ischemic core and penumbra were carefully sampled and compared to the corresponding contralateral (healthy) core and penumbra regions at 6 and 24 h post PACAP38 or saline injections. Both reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to examine targeted gene expressions and the collapsin response mediator protein 2 (CRMP2) protein profiles, respectively. Clear differences in expression of genes and CRMP2 protein abundance and degradation product/short isoform was observed between ischemic core and penumbra and also compared to the contralateral healthy tissues after PACAP38 or saline treatment. Results indicate the importance of region-specific analyses to further identify, localize and functionally analyse target molecular factors for clarifying the neuroprotective function of PACAP38.

Background: To review the role of PACAP38 in human models of primary headaches, discuss possible mechanisms of PACAP38-induced migraine, and outline future directions. Discussion: Experimental studies have established PACAP38 as a potent pharmacological “trigger” molecule of migraine-like attacks. These studies have also revealed a heterogeneous PACAP38 migraine response in migraine without aura patients. In addition, findings from brain imaging studies have demonstrated neuronal and vascular changes in migraine patients both ictally and interictally after PACAP38 infusion. Conclusion: Human migraine models have shed light on the importance of PACAP38 in the pathophysiology of primary headaches. These studies have also pointed to the PAC1 receptor and the PACAP38 molecule itself as target sites for drug testing. Future research should seek to understand the mechanisms underlying PACAP38-induced migraine. The results from an ongoing proof of concept randomized clinical trial may reveal the therapeutic potential of anti-PAC1 receptor antibodies for migraine prevention. [ABSTRACT FROM AUTHOR]

Here, we review the role of pituitary adenylate cyclase-activating peptide-38 (PACAP38) in migraine and cluster headache (CH). Mounting evidence implicates signaling molecule PACAP38 in the pathophysiology of migraine. Human provocation studies show PACAP38 induces migraine attacks in migraine patients without aura and marked and sustained dilation of extracerebral arteries. PACAP38 selectively targets the PAC1 receptor making this receptor a promising candidate for targeted migraine therapy. Randomized clinical trials are warranted to pursue this possible treatment pathway. PACAP38 provocation studies in CH could elucidate possible involvement of PACAP38 in CH pathophysiology and predict efficacy of PACAP38 antagonists in this primary headache. [ABSTRACT FROM AUTHOR]

Numerous studies investigated the localization of pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors in different tumors and described the effects of analogs on tumor growth to show its potential role in oncogenesis. Recently, our research group has found significantly lower levels of PACAP27-like immunorreactivity (LI) and PACAP38-LI in different human samples of primary small cell lung cancer and colon cancer compared to normal healthy tissues. There are only few human studies showing the presence of PACAP and its receptors in urogenital tumors; therefore, the aim of the present study was to compare PACAP-LI in different healthy and pathological human samples from urogenital organs (kidney, urinary bladder, prostate, testis) with radioimmunoassay (RIA) method. Similar to our earlier observations, the PACAP27-LI was significantly lower compared to PACAP38-LI in all samples. We did not find significant alterations in PACAP-LI between healthy and tumoral samples from the urinary bladder and testis. On the other hand, we found significantly lower PACAP38-LI level in kidney tumors compared with healthy tissue samples, and we showed higher PACAP27-LI in prostatic cancer compared to samples from benign prostatic hyperplasia. These data indicate that PACAP levels of different tissue samples are altered under pathological conditions suggesting a potential role of PACAP in the development of different urogenital tumors. [ABSTRACT FROM AUTHOR]

Our group has been systematically investigating the effects of the neuropeptide pituitary adenylate-cyclase activating polypeptide (PACAP) on the ischemic brain. To do so, we have established and utilized the permanent middle cerebral artery occlusion (PMCAO) mouse model, in which PACAP38 (1 pmol) injection is given intracerebroventrically and compared to a control saline (0.9% sodium chloride, NaCl) injection, to unravel genome-wide gene expression changes using a high-throughput DNA microarray analysis approach. In our previous studies, we have accumulated a large volume of data (gene inventory) from the whole brain (ipsilateral and contralateral hemispheres) after both PMCAO and post-PACAP38 injection. In our latest research, we have targeted specifically infarct or ischemic core (hereafter abbreviated IC) and penumbra (hereafter abbreviated P) post-PACAP38 injections in order to re-examine the transcriptome at 6 and 24 h post injection. The current study aims to delineate the specificity of expression and localization of differentially expressed molecular factors influenced by PACAP38 in the IC and P regions. Utilizing the mouse 4 × 44 K whole genome DNA chip we show numerous changes (≧/≦ 1.5/0.75-fold) at both 6 h (654 and 456, and 522 and 449 up- and down-regulated genes for IC and P, respectively) and 24 h (2568 and 2684, and 1947 and 1592 up- and down-regulated genes for IC and P, respectively) after PACAP38 treatment. Among the gene inventories obtained here, two genes, brain-derived neurotrophic factor (Bdnf) and transthyretin (Ttr) were found to be induced by PACAP38 treatment, which we had not been able to identify previously using the whole hemisphere transcriptome analysis. Using bioinformatics analysis by pathway- or specific-disease-state focused gene classifications and Ingenuity Pathway Analysis (IPA) the differentially expressed genes are functionally classified and discussed. Among these, we specifically discuss some novel and previously identified genes, such as alpha hemoglobin stabilizing protein (Ahsp), cathelicidin antimicrobial peptide (Camp), chemokines, interferon beta 1 (Ifnb1), and interleukin 6 (Il6) in context of PACAP38-mediated neuroprotection in the ischemic brain. Taken together, the DNA microarray analysis provides not only a great resource for further study, but also reinforces the importance of region-specific analyses in genome-wide identification of target molecular factors that might play a role in the neuroprotective function of PACAP38. [ABSTRACT FROM AUTHOR]

The production of reactive oxygen species (ROS) and the resulting oxidative stress in mice in response to a controlled cortical impact (CCI) are typical exacerbating factors associated with traumatic brain injury (TBI). Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38) is a multifunctional peptide that has been shown to exhibit neuroprotective effects in response to a diverse range of injuries to neuronal cells. We recently reported that PACAP38 might regulate oxidative stress in mice. The aim of the present study was to determine whether PACAP38 exerts neuroprotective effects by regulating oxidative stress in mice with TBI. Reactive oxidative metabolites (ROMs) and biological antioxidant potential (BAP) were measured in male C57Bl/6 mice before and 3, 4, and 24 h after CCI. PACAP38 was administered intravenously immediately following CCI, and immunostaining for the oxidative stress indicator nitrotyrosine (NT), and for neuronal death as an indicator of the area affected by TBI, was measured 24 h later. Western blot experiments to determine antioxidant activity [as indicated by superoxide dismutase-2 (SOD-2) and glutathione peroxidase 1 (GPx-1)] in the neocortical region were also performed 3 h post-CCI. Results showed that plasma BAP and ROM levels were dramatically increased 3 h after CCI. PACAP38 suppressed the extent of TBI and NT-positive regions 24 h after CCI, and increased SOD-2 and GPx-1 levels in both hemispheres. Taken together, these results suggest that increasing antioxidant might be involving in the neuroprotective effect of PACAP38 in mice subjected to a CCI. [ABSTRACT FROM AUTHOR]

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide with widespread occurrence in the nervous system and peripheral organs, including the mammary gland. Previously, we have shown that PACAP38 is present in the human milk at higher levels than in respective blood samples. However, it is not known how PACAP levels and the expression of PAC1 receptor change during lactation. Therefore, the aim of our study was to investigate PACAP38-like immunoreactivity (PACAP38-LI) in human colostrums and transitional and mature milk during lactation and to compare the expression of PAC1 receptors in lactating and non-lactating mammary glands. We found that PACAP38-LI was significantly higher in human colostrum samples than in the transitional and mature milk. PACAP38-LI did not show any significant changes within the first 10-month period of lactation, but a significant increase was observed thereafter, up to the examined 17th month. Weak expression of PAC1 receptors was detected in non-lactating sheep and human mammary glands, but a significant increase was observed in the lactating sheep samples. In summary, the present study is the first to show changes of PACAP levels in human milk during lactation. The presence of PACAP in the milk suggests a potential role in the development of newborn, while the increased expressions of PAC1 receptors on lactating breast may indicate a PACAP38/PAC1 interaction in the mammary gland during lactation. [ABSTRACT FROM AUTHOR]

The neuropeptide pituitary adenylate cyclase-activating polypeptide 38 (PACAP38) has been implicated in the induction of synaptic plasticity at the excitatory glutamatergic synapse. In particular, recent studies have shown that it is involved in the regulation of Nmethyl- D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor activation. Here we demonstrate the effect of PACAP38 on the modulation of dendritic spine morphology through a disintegrin and metalloproteinase 10 (ADAM10)-N-cadherin-AMPA receptor signaling pathway. Treatment of primary hippocampal neurons with PACAP38 induced an accumulation of ADAM10 at the postsynaptic membrane. This event led to a significant decrease of dendritic spine head width and to a concomitant reduction of GluR1 colocalization with postsynaptic markers. The PACAP38-induced effect on dendritic spine head width was prevented by either treatment with the ADAM10-specific inhibitor or transfection of a cleavage-defective N-cadherin construct mutated in the ADAM10 cleavage site. Overall, our findings reveal that PACAP38 is involved in the modulation of dendritic spine morphology in hippocampal neurons, and assign to the ADAM10-N-cadherin signaling pathway a crucial role in this modification of the excitatory glutamatergic synapse. [ABSTRACT FROM AUTHOR]

Aim: To explore a possible relationship between vasodilatation and delayed headache we examined the effect of pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) on the middle meningeal artery (MMA) and middle cerebral artery (MCA) using high resolution magnetic resonance angiography (MRA).Methods: In a double-blind, randomized, placebo-controlled study 14 healthy volunteers were scanned repeatedly after infusion (20 min) of 10 pmol/kg/min PACAP38 or placebo. In addition, four participants were scanned following subcutaneous sumatriptan (6 mg).Results: We found significant dilatation of the MMA (p = 0.00001), but not of the MCA (p = 0.50) after PACAP38. There was no change after placebo (p > 0.40). Vasodilatation (range 16–23%) lasted more than 5 h. Sumatriptan selectively contracted the MMA by 12.3% (p = 0.043).Conclusion: PACAP38-induced headache is associated with prolonged dilatation of the MMA but not of the MCA. Sumatriptan relieves headache in parallel with contraction of the MMA but not of the MCA. [ABSTRACT FROM PUBLISHER]

Objective: We pharmacologically characterized pituitary adenylate cyclase—activating polypeptides (PACAPs), vasoactive intestinal peptide (VIP) and the VPAC1, VPAC2 and PAC1 receptors in human meningeal (for their role in migraine) and coronary (for potential side effects) arteries.Methods: Concentration response curves to PACAP38, PACAP27, VIP and the VPAC1 receptor agonist ([Lys15,Arg16,Leu27]-VIP[1-7]-GRF[8-27]) were constructed in the absence or presence of the PAC1 receptor antagonist PACAP6-38 or the VPAC1 receptor antagonist, PG97269. mRNA expression was measured using qPCR. Results: PACAP38 was less potent than VIP in both arteries. Both peptides had lower potency and efficacy in meningeal than in coronary arteries, while mRNA expression of VPAC1 receptor was more pronounced in meningeal arteries. PACAP6-38 reduced the Emax of PACAP27, while PG97269 right-shifted the VIP-induced relaxation curve only in the coronary arteries.Conclusion: The direct vasodilatory effect of VIP and PACAP might be less relevant than the central effect of this compound in migraine pathogenesis. [ABSTRACT FROM PUBLISHER]

Pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide with survival-promoting actions, has been observed in endocrine organs and is thought to play a role in reproductive functions, including pregnancy. PACAP occurs in two forms, 27 and 38 amino acid residues, with PACAP38 being the predominant form in human tissues. In the present study, we determined the concentrations of PACAP38 and PACAP27 in first-trimester and full-term human placentas using radioimmunoassay. We found high levels of PACAP38 and lower levels of PACAP27 in different parts of the full-term human placenta. PACAP38 content increased in the placenta during pregnancy, both on the maternal side and on the fetal side. The effects of PACAP on the survival of JAR human choriocarcinoma cells were investigated using flow cytometry and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) cell viability assay in cells exposed to the widely used chemotherapeutic agent methotrexate (MTX). It was found that PACAP neither influenced the survival of JAR cytotrophoblast cells nor affected cellular response to the death-inducing effect of the chemotherapeutic agent MTX. The present observations further support the significance of PACAP in the human placenta. The observation that PACAP did not influence the effects of MTX may have future clinical importance, showing that PACAP does not decrease the effects of certain chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

Pituitary adenylate cyclase-activating peptide-38 (PACAP38) and vasoactive intestinal peptide (VIP) belong to the same secretin–glucagon superfamily and are present in nerve fibers in dura and skin. Using a model of acute cutaneous pain we explored differences in pain perception and vasomotor responses between PACAP38 and VIP in 16 healthy volunteers in a double-blind, placebo-controlled, crossover study. All participants received intradermal injections of 200 pmol PACAP38, 200 pmol VIP and placebo into the volar forearm. Measurements included pain intensity on a visual analog scale (VAS), blood flow by laser Doppler flowmetry, visual flare and wheal. Pain intensities after PACAP38 and VIP were mild and limited to a short time of about 100 s after injection. The area under the VAS-time curve was larger following PACAP38 ( P = 0.004) and VIP ( P = 0.01) compared to placebo. We found no statistical difference in pain perception between PACAP38 and VIP. Skin blood flow increase, flare and wheal were larger after both PACAP38 ( P = 0.011) and VIP ( P = 0.001) compared to placebo. VIP induced a considerably larger increase in skin blood flow, flare and wheal than PACAP38 ( P = 0.002). In conclusion, we found that peripheral nociceptive cutaneous responses elicited by PACAP38 and VIP are similar in healthy volunteers. This suggests that acute pain and vasomotor responses following intradermal injections of PACAP38 and VIP are primarily mediated by VPAC receptors. [ABSTRACT FROM AUTHOR]

Abstract: Neurotrophic factors such as pituitary adenylate cyclase activating polypeptide (PACAP38) are promising therapeutics for neurodegenerative diseases. However, delivery of trophic factors into brain neurons remains a challenge. The objective of this study is to determine whether adeno-associated virus (AAV) can mediate PACAP38 gene delivery into neurons in vitro and if transduction of AAV/PACAP38 into cortical neurons protects cells against neurotoxic insult. Primary cortical neuronal cultures are transduced with rAAV/PACAP38/GFP and cell survival against the nitric oxide releasing neurotoxin sodium nitroprusside (SNP) determined. GFP expression, a surrogate marker for successful transduction, is detected using fluorescent microscopy. The results show expression of GFP transgene and AAV capsid proteins in neurons. PACAP38 transduction significantly increases cell survival of neurons exposed to SNP. These results support the feasibility of using AAV-mediated delivery of PACAP38 to enhance neuronal survival and suggest that AAV-delivered PACAP38 maybe a therapeutic strategy for neurodegenerative diseases. [Copyright &y& Elsevier]

The pituitary adenylate cyclase-activating peptide (PACAP) is involved in many processes of the developing and mature central nervous system, such as proliferation, differentiation, apoptosis, neurotransmission, inflammation and neuroprotection. Alternative posttranslational processing of PACAP results in two biologically active, amidated 27- and 38-amino acid peptides termed PACAP27 and PACAP38. In the present study, we examined whether traumatic brain injury (TBI) affects cellular immunopositivity for PACAP27 and PACAP38. Patients ( n = 55) were classified into three groups dependent on their survival time (under 24 h, between 24 h and 7 days and between 7 days and 99 days postinjury). PACAP27 and PACAP38 were expressed by neurons and glial cells in normal human neocortex ( n = 10). Following TBI, the total number of PACAP27- and PACAP38-positive cells was significantly decreased for a prolonged survival period within the traumatized neocortex. In the pericontusional cortex, the number of cells expressing PACAP27 and PACAP38 was significantly increased at all survival times examined. Triple immunofluorescence examinations revealed a significant increase in the absolute numbers of GFAP-positive reactive astrocytes as well as a decrease in the CNP-positive oligodendrocytes, each coexpressing PACAP27 or PACAP38 in the contusional and pericontusional cortex. We hypothesize that the increase of glial PACAP immunoreactivity may be interpreted as part of a complex endogenous neuroprotective response in the pericontusional regions, but the precise role of PACAP following TBI is yet to be determined. [ABSTRACT FROM AUTHOR]

Abstract: PACAP38 is an endogenous peptide located in trigeminal perivascular nerve fibers in the brain. It reduces neuronal loss and infarct size in animal stroke models and has been proposed a candidate substance for human clinical studies of stroke. The effect on systemic hemodynamics and regional cerebral blood flow (rCBF) is not well understood. We here present the first study of the effect of PACAP38 on cerebral hemodynamics in humans. PACAP (10 pmol kg−1 min−1) or placebo (0.9% saline) was infused for 20 min into 12 healthy young volunteers in a cross over, double blind study. rCBF was measured with SPECT and 133Xe inhalation and mean blood flow velocity in the middle cerebral artery was measured with transcranial Doppler ultrasonography. End tidal partial pressure of CO2 (PetCO2) and vital parameters were recorded throughout the 2 hour study period. PACAP38 decreased rCBF in all regions of interest (ROIs) by ∼3–10%, though not uniformly significant. PetCO2 decreased significantly during PACAP38 infusion compared to placebo (P =0.032), peak decrease was 8.9±3.8%. After correction for PetCO2, rCBF remained unchanged in most ROIs. Heart rate increased 61.9±22.4% (P <0.0001 vs. placebo). These findings suggest that PACAP38 has no major direct effect on rCBF in healthy volunteers. The marked increase in heart rate and the reduction in rCBF caused by decreased PetCO2 are important dose-limiting factors to consider in future clinical studies. [Copyright &y& Elsevier]

We developed a sensitive and specific immunoassay system for human neuronal nitric oxide synthase (hnNOS) using synthetic hnNOS(998–1024) peptide and anti-hnNOS(998–1024) antibody. The novel antibody and radioimmunoassay system revealed a typical nNOS protein in human neuroblastoma NB-OK-1 cell (160 kDa, 180 fmol/106 cells). The kinetic parameters of the enzyme were Km=4.88 μM and Vmax=4.34 pmol/min/mg protein for l-arginine. On incubation of NB-OK-1 cell for 24 h, betamethasone phosphate decreased both nNOS-immunoreactivity (nNOS-IR) and enzymatic activity in the cell dose-dependently. On the other hand, pituitary adenylate cyclase activating polypeptide(1–38) (PACAP38) increased both nNOS-IR and enzymatic activity at concentrations of 10−10 and 10−9 M, but inversely decreased both at 10−7 M. These suggest the positive and negative implications of endogenous NO in proliferation and differentiation of the cell, which support mitogenic activity of NO generated by nNOS in the cell. The present findings also provided evidence that the quantitative change of nNOS protein controls the integrated activity of the enzyme in the cell and, in turn, substantiate the validity and reliability of the present immunoassay system for hnNOS and its practical usefulness. [Copyright &y& Elsevier]

We examined the mechanisms of effects of vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase activating polypeptide (PACAP) 27 and PACAP38 on spontaneously occurring pressure waves in ex vivo perfused rat duodenum. VIP and PACAPs dose-dependently reduced the percentage motor index of pressure waves; this reduction was not prevented by atropine, hexamethonium or tetrodotoxin (TTX). VIP and PACAPs abolished acetylcholine-induced stimulation of pressure waves, even in the presence of TTX. These findings suggest that VIP and PACAPs may exert direct inhibitory effects via VIP/PACAP receptors located on smooth muscle rather than via cholinergic receptors. The inhibitory effects of VIP and PACAPs were partially antagonized by the VIP receptor antagonists VIP(10–28), suggesting that VIP and PACAPs share common receptor sites on intestinal smooth muscle. The effects of VIP and PACAPs were completely antagonized by nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine (L-NA), suggesting that NO mediates the inhibitory effects of VIP and PACAPs on duodenal motility. Furthermore, single injection of L-NA stimulated spontaneously occurring pressure waves, while VIP(10–28) did not affect them. These findings suggest that VIP/PACAPs and NO strongly interact as an inhibitory mediator on duodenal motility, but that their modes of action in doing so may differ. [ABSTRACT FROM AUTHOR]

Traumatic optic neuropathy (TON) refers to optic nerve damage caused by trauma, leading to partial or complete loss of vision. The primary treatment options, such as hormonal therapy and surgery, have limited efficacy. Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38), a functional endogenous neuroprotective peptide, has emerged as a promising therapeutic agent. In this study, we used rat retinal ganglion cell (RGC) exosomes as nanosized vesicles for the delivery of PACAP38 loaded via the exosomal anchor peptide CP05 (EXO PACAP38 ). EXO PACAP38 showed greater uptake efficiency in vitro and in vivo than PACAP38. The results showed that EXO PACAP38 significantly enhanced the RGC survival rate and retinal nerve fiber layer thickness in a rat TON model. Moreover, EXO PACAP38 significantly promoted axon regeneration and optic nerve function after injury. These findings indicate that EXO PACAP38 can be used as a treatment option and may have therapeutic implications for patients with TON., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Wang, Li, Guo, Dong, Liao, Du, Wang, Yin and Yan.)