Search Results (111)

Background: Pituitary adenylate cyclase-activating polypeptide (PACAP) functions as an anti-atherogenic neuropeptide. Maxadilan, a PAC1 receptor agonist, offers atheroprotection by acting downstream of vascular inflammation caused by hypercholesterolemia. This study aims to explore how PACAP and Maxadilan influence migration and apoptosis in human coronary artery smooth muscle cells (HCASMCs). Methods: To investigate the role of PACAP deficiency in the pathogenesis of atherosclerosis under standard chow (SC) in vivo, PACAP^−/−-mice were crossed with ApoE^−/−-mice to generate PACAP^−/−/ApoE^−/−-mice. The whole aorta was isolated and stained with OilRedO (ORO). Atherosclerotic lesions and lumen stenosis in the brachiocephalic trunk were quantified using ImageJ 1.54p (Fiji). To further investigate the role of PACAP and Maxadilan in the pathogenesis of atherosclerosis with special respect to HCASMC under a lipid-enriched environment, HCASMCs were treated with oxLDL, with or without PACAP or Maxadilan. Uptake and accumulation of oxLDL were analyzed using Bodipy^TM493/503, and cell viability was assessed with PrestoBlue^®. Cell migration was evaluated using the scratch assay and the MRI wound-healing tool in ImageJ (Fiji). Mitochondrial morphology was examined with MitoTracker Green and the MiNA tool in ImageJ (Fiji). Apoptotic processes were analyzed by Western blot, immunocytofluorescence staining, and ELISA. Results: In vivo, PACAP^−/−/ApoE^−/−-mice showed increased lumen stenosis and decreased plaque burden compared with ApoE^−/−-mice. In vitro, PACAP enhanced the viability of oxLDL-treated HCASMCs, while neither PACAP nor Maxadilan influenced lipid content in HCASMCs, regardless of oxLDL presence. Both oxLDL and PACAP slowed cell migration, but Maxadilan increased migration in oxLDL-treated HCASMCs. The protein level of the proliferation marker Ki67 was reduced in cells treated with oxLDL and Maxadilan. Additionally, BAX, which promotes intrinsic apoptosis, was elevated in HCASMCs stimulated with Maxadilan and oxLDL. Investigations of mitochondrial morphology indicated that oxLDL and PACAP increased the individual and network structures, with a decrease in branches per network. Conclusion: Our data highlight the complex role of the PACAP/PAC1 system in vascular pathology and suggest that selective modulation—such as targeted PAC1 activation or PACAP supplementation—could lead to new strategies for stabilizing atherosclerotic plaques. In the long term, this could improve the balance between plaque formation and vascular function. Full article

Sensory neurons at barrier tissues were once seen as passive detectors of environmental stimuli. However, in the last five years, increasing evidence has challenged this view, redefining these cells as active immune sentinels that directly affect tissue immunity in the skin, lungs, and gastrointestinal tract. Nociceptors and pruriceptors express various immune-sensing receptors, including Toll-like receptors, cytokine receptors, and alarmin sensors, which allow them to directly detect pathogens, allergens, and tissue damage. When activated, sensory neurons quickly release neuropeptides such as calcitonin gene-related peptide (CGRP), substance P, vasoactive intestinal peptide (VIP), and PACAP (pituitary adenylate cyclase-activating polypeptide), which guide immune cell recruitment, activation, and resolution. Reciprocally, immune-derived mediators, including IL-33, IL-31, thymic stromal lymphopoietin (TSLP), IL-4/IL-13, and TNF-α, modulate neuronal excitability and plasticity, forming bidirectional neuroimmune circuits that control inflammation, host defense, pain, and itch. Landmark studies published in 2024–2025, including neuronal control of gut Treg function and the identification of sensory nerve immune niches, have further refined this framework and revealed tissue-specific circuit specialization. This review synthesizes recent insights from molecular, cellular, and systems levels into the sensory neuroimmune axis, emphasizes its protective versus pathogenic roles, and critically evaluates emerging therapeutic strategies and safety concerns, positioning sensory neuroimmunology as a unifying framework for tissue barrier homeostasis and disease. Full article

The neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) have emerged as potent modulators of immune responses during sepsis, yet their roles remain complex, alternating between protective and permissive depending on timing, tissue compartment, and inflammatory context. This review presents a historical assessment of VIP and PACAP in sepsis research, highlighting the evolution of conceptual advances across five decades. Starting in the 1980s, early studies revealed that VIP levels rise during endotoxemia and correlated with hypotension and mortality, suggesting a deleterious role. By the 1990s, research pivoted toward understanding gut-derived VIP and its interaction with nitric oxide, culminating in the classification of VIP and PACAP as “macrophage deactivating factors” that downregulate TNFα and IL-6. The 2000s further clarified their cell-specific actions through VPAC1/2 and PAC1 receptors, showing anti-inflammatory effects on both innate and adaptive immune cells, while illuminating delivery challenges overcome by liposomal encapsulation. The 2010s expanded this narrative by dissecting receptor dynamics, gut barrier regulation, and VIP’s role in neuroimmune crosstalk and thrombo-inflammation. Most recently, studies in the 2020s provide a nuanced view of how VIP suppresses inflammatory damage but also enables pathogen persistence during live bacterial infection, implicating VIP signaling in trade-offs between tolerance and clearance. Across this chronological framework, VIP and PACAP have oscillated between friend, foe, and frenemy, underscoring the importance of context in leveraging their therapeutic potential in sepsis. Full article

Background: Moderate physical activity (PA) exerts powerful systemic and neuroprotective effects, reducing chronic disease risk and enhancing cognitive and psychological well-being. PA promotes brain plasticity by upregulating neurotrophic factors and stimulating neurogenesis. Given the established role of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) in neuronal survival, differentiation, and anti-apoptotic signaling, we aimed to investigate whether moderate PA modulates the endogenous expression of PACAP and its specific receptor PAC1R in the DG and cerebellar cortex. Methods: To this end, twenty-four rats were distributed into sedentary or exercise groups. Immunohistochemical and Western blot analyses were performed to assess PACAP and PAC1R expression. Co-expression with doublecortin (DCX), a marker of immature neurons, was evaluated to explore the direct relationship between PACAP signaling and neurogenesis. Results: Our results showed that moderate PA induced a significant up-regulation of PACAP and PAC1R in both the DG and cerebellar cortex compared to sedentary controls. Moreover, high co-expression of PACAP and DCX was detected in these regions, suggesting an involvement of PACAP in exercise-induced neurogenic processes. Conclusions: These findings demonstrate that moderate physical activity is associated with enhanced PACAP/PAC1R signaling and DCX expression in neurogenic regions, warranting further investigation into its specific contribution to exercise-induced brain plasticity. Full article

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a small neuropeptide detected first in the hypothalamo–hypophyseal system; recently, it has also been identified in peripheral organs and in tumours. It is well demonstrated that PACAP exerts cell- and tissue-protecting effects in various stressful conditions and helps to maintain tissue homeostasis. In melanoma, the anti-invasive effect of PACAP has been demonstrated; however, there is also existing sporadic data which proves PACAP plays a role in melanoma progression. The major goal of our study was to investigate the signalling targets of PACAP in A2058 and WM35 melanoma cell lines in vitro. Various molecular players of melanocyte differentiation and function responded to PACAP application. SOX9 expression increased while SOX10 expression decreased and CREB signalling did not change. The expression level of TYRP1 decreased, while DCT elevated, and MITF expression showed changes at the mRNA level and in its subcellular localisation. In contrast, the amount of hyaluronan (HA) and expressions of its synthases, as well as RHAMM, increased, indicating the role of PACAP in secretion of an HA-rich matrix. In parallel with these results, we detected elevated hyaluronidase2 (Hyal2) expression in the presence of PACAP. On the other hand, alfaV and beta3 integrin expressions did not alter significantly. Our results demonstrate that exogenous PACAP modulates the expression of multiple target molecules in melanoma cells. Some of the significantly responding molecules take part in hyaluronan homeostasis, suggesting an effect of PACAP on tumour matrix composition, through which it can modulate invasiveness of melanoma cells. Full article

The calyx of Held is a giant axo-somatic synapse classically confined to the auditory brainstem. We recently identified morphologically similar calyx-like terminals in the extended amygdala (EA) that arise from the ventrolateral parabrachial complex and co-express PACAP, CGRP, VAChT, VGluT1, and VGluT2, targeting PKCδ⁺/GluD1⁺ EA neurons. Here, we asked whether this parabrachial–EA pathway participates in compensation during acute hypotension. In rats given hydralazine (10 mg/kg, i.p.), we quantified Fos protein during an early phase (60 min) and a late phase (120 min). Early after hypotension, Fos surged in a discrete subpopulation of the parabrachial Kölliker–Fuse (KF) region and in the EA, whereas magnocellular neurons of the supraoptic and paraventricular nuclei (SON/PVN) remained largely silent. By 120 min, magnocellular SON/PVN neurons were robustly Fos-positive. Confocal immunohistochemistry showed that most Fos+ PKCδ⁺/GluD1⁺ EA neurons were encircled by PACAP+ perisomatic terminals (80.8%), of which the majority co-expressed VGluT1 (88.1%). RNAscope in situ hybridization further identified a selective KF population co-expressing Adcyap1 (PACAP) and Slc17a7 (VGluT1) that became fos-positive during the early phase. Together, these data suggest that a KF PACAP⁺/VGluT1⁺ projection forms calyceal terminals around PKCδ⁺/GluD1⁺ EA neurons, providing a high-fidelity route for rapid autonomic rebound to falling blood pressure, while slower endocrine support is subsequently recruited via neurohormone-magnocellular activation. This work links multimodal parabrachial output to temporally layered autonomic–neuroendocrine control. Full article

One of most important parts of the female genital tract is the uterine cervix, both from the anatomical as well as physiological points of view. As there is currently a lack of detailed information on the presence, distribution pattern(s), and the chemical coding of phoenixin (PNX)-containing dorsal root ganglia (DRG) neurons supplying the porcine uterine cervix, this study, using combined retrograde tracing and double-immunofluorescence techniques, was aimed at analyzing (i) the distribution pattern of uterine cervix-supplying sensory neurons (UC-SNs) at the particular spinal cord levels, (ii) their intraganglionic distribution, and (iii) the patterns of PNX co-expression with other biologically active substances. UC-SNs were identified by the presence of deposits of Fast Blue (FB), in DRG of thoracic (Th10–Th15), lumbar (L1–L5) and sacral (S2–S4) spinal cord segments. FB⁺/PNX⁺ neurons constitute approximately 33% of all UC-SNs, 73% at the L, and 27% at the S neuromeres. These neurons were mainly small sized (52%), with a slightly smaller population of medium-sized cells (40%), while large-diameter cells made up the least numerous population (8%). The vast majority of FB⁺/PNX⁺ neurons simultaneously contained calcitonin gene-related peptide (CGRP; 80.9%) or substance P (SP; 77.9%); one-third of them showed immunoreactivity toward neuronal nitric oxide synthase (nNOS; 34%), while PNX⁺ UC-SNs containing pituitary adenylate cyclase-activating polypeptide (PACAP), galanin (GAL), calretinin (CRT), or somatostatin (SOM) formed significantly smaller populations (21.4%, 7.4%, 3.1%, and 0.7%, respectively). The results of the present study demonstrate the presence of PNX in DRG UC-SNs, and its co-occurrence with numerous neurotransmitters suggesting a putative role for this neuropeptide in the transmission of various types of sensory information and possible effects on the functioning of this organ in the body. Full article

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide exerting, among others, strong trophic and protective effects. It plays a role in several physiological functions, including glucose homeostasis. The protective effects of PACAP are mainly mediated via its specific PAC1 receptor by stimulating anti-inflammatory, anti-apoptotic and antioxidant pathways. The aim of the present review is to summarize data on the protective effects of PACAP in the three major complications of diabetes, retinopathy, nephropathy and neuropathy, as well as some other complications. In type 1 and type 2 diabetic retinopathy models and in glucose-exposed cells of the eye, PACAP counteracted the degeneration of retinal layers and inhibited apoptosis and factors leading to abnormal vessel growth. In models of nephropathy, kidney morphology was better retained after PACAP administration, with decreased apoptosis and fibrosis. In diabetic neuropathy, PACAP protected against axonal–myelin lesions and less activation in pain processing centers. This neuropeptide has several other beneficial effects in diabetes-induced complications like altered vascular response, cognitive deficits and atherosclerosis. The promising therapeutic effects of PACAP in several pathological conditions have encouraged researchers to design PACAP-related drugs and to develop ways to enhance tissue delivery. These intentions are expected to result in overcoming the hurdles preventing PACAP from being introduced into therapeutic treatments, including diabetes-related conditions. Full article

Maternal behavior encompasses a range of biologically driven responses whose expression and duration vary across species. Maternal responses rely on robust adaptive changes in the female brain, enabling mothers to engage in caregiving, nourishing, and offspring protection. Morphological and functional changes in the maternal brain enhance sensitivity to offspring cues, eliciting maternal behaviors, rewarding responses, and social processing stimuli essential for parenting. Maternal behavior comprises a range of biological responses that extend beyond basic actions, reflecting a complex, evolutionarily shaped neurobiological adaptation. These behaviors can be broadly categorized into direct behaviors, which are explicitly aimed at the care of the offspring, and indirect behaviors that, overall, ensure the protection, nourishment, and survival of the newborn. The secretion of main neuropeptide hormones, such as oxytocin (OT), prolactin (PRL), and placental lactogens (PLs), during the peripartum period, is relevant for inducing and regulating maternal responses to offspring cues, including suckling behavior. Although PRL is primarily associated with reproductive and parental functions in vertebrates, it also modulates distinct neural functions during pregnancy that extend from lactogenesis to adult neurogenesis, neuroprotection, and neuroplasticity, all of which contribute to preparing the maternal brain for motherhood and parenting interactions. Parvocellular OT-containing neurons in the paraventricular nucleus (PVN) and in the anterior hypothalamic nucleus (AHN) project axon collaterals to the medial preoptic area, which, in turn, projects to the nucleus accumbens (NACC) and lateral habenula (lHb) via the retrorubral field (RRF) and the ventral tegmental area (VTA), which mediate the motivational aspects of maternal responses to offspring cues. The reshaping process of the brain and neural networks implicated in motherhood depends on several factors, such as up- and downregulation of neuronal gene expression of bioactive peptide hormones (i.e., OT, PRL, TIP-39, galanin, spexin, pituitary adenylate cyclase-activating polypeptide (PACAP), corticotropin-releasing hormone (CRH), peptide receptors, and transcription factors (i.e., c-fos and pSTAT)) in target neurons in hypothalamic nuclei, mesolimbic areas, the hippocampus, and the brainstem, which, overall, regulate the expression of maternal behavior to offspring cues, as shown in postpartum female rodents. In this review, we describe the modulatory neuropeptides, the neural networks underlying peptide transmission systems, and cell signaling involved in parenthood. We highlight the dysregulation of neuropeptide hormones and their receptors in the central nervous system in relation to psychiatric disorders. Full article

Background/Objectives: To prevent flap failure, adequate tissue perfusion and effective regenerative processes, undisturbed wound healing are essential, among others. To improve wound healing, various locally and systematically administered pharmacons can be used. This study investigated the effect of PACAP 1-38 (pituitary adenylate cyclase activating polypeptide) and BGP-15 (a nicotinic amidoxime derivative) on the healing of epigastric fasciocutaneous flaps exposed to ischemia–reperfusion (I/R). Methods: Wistar rats were randomly divided into control (no substance), PACAP 1-38, and BGP-15 groups. Groin flaps were prepared bilaterally. The left flap was exposed to 120 min of ischemia prior to suturing it back. We applied wound gels containing substances. Laboratory tests (hematology, erythrocyte deformability, and aggregation) were performed before surgery on the 1st, 3rd, and 7th postoperative days. Lastly, flap skin samples were taken for histological and tensile strength measurements. Results: Impaired erythrocyte deformability and enhanced aggregation were found because of flap I/R. The pharmacons were able to reduce the systemic micro-rheological impairment to varying degrees. The tensile strength increased in the areas of better perfusion. Conclusions: The anti-inflammatory effects of PACAP 1-38 and BPG-15, as well as the impact of PACAP 1-38 on collagen and elastic fiber composition, have been demonstrated. Full article

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide that plays significant regulatory roles in the differentiation of the central nervous system and peripheral organs. A lack of the neuropeptide can lead to abnormalities in long bone development. In callus formation, a possible signaling balance shift in PACAP KO mice has been demonstrated, but Notch signalization, with its potential connection with PACAP 1-38, has not been investigated in ossification. Our main goal was to show connections between PACAP and Notch signaling in osteogenesis. Notch signalization showed an elevation in the long bones of PACAP-gene-deficient mice, and it was also elevated during the PACAP 1-38 treatment of UMR-106 and MC3T3-E1 osteogenic cells. Moreover, the inhibition of Notch signaling was compensated by the addition of PACAP 1-38 in vitro. The inorganic and organic matrix production of UMR-106 cells was increased during PACAP 1-38 treatment under the inhibition of Notch signaling. As a possible common target, the expression and nuclear translocation of NFATc1 transcription factor was increased during the disturbance of PACAP and Notch signaling. Our results indicate a possible synergistic regulation during bone formation by PACAP and Notch signalization. The crosstalk between Notch and PACAP signaling pathways highlights the complexity of bone development and homeostasis. Full article

Microglial cells, the resident immune cells of the central nervous system (CNS), are essential for maintaining CNS homeostasis. Dysregulation of microglial function is implicated in the pathogenesis of various neurodegenerative diseases. Vasoactive intestinal polypeptide receptors 1 and 2 (VPAC1 and VPAC2) are G-protein-coupled receptors (GPCRs) expressed by microglia, with their primary ligands being pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP). However, the specific roles of VPAC-type receptors in microglial regulation remain poorly understood. In this study, we generated VPAC1^+/− and VPAC2^+/− BV2 microglial cell lines using CRISPR-Cas9 gene editing and conducted a series of biological and molecular assays to elucidate the functions of these receptors. Our findings demonstrated that both mutant cell lines exhibited a polarized phenotype and increased migratory activity. VPAC1^+/− cells showed enhanced survivability and baseline activation of the unfolded protein response (UPR), a protective mechanism triggered by endoplasmic reticulum (ER) stress, whereas this response appeared impaired in VPAC2^+/− cells. In contrast, under lipopolysaccharide (LPS)-induced inflammatory conditions, UPR activation was impaired in VPAC1^+/− cells but restored in VPAC2^+/− cells, resulting in improved survival of VPAC2^+/− cells, whereas VPAC1^+/− cells exhibited reduced resilience. Overall, our findings suggest that VPAC1 and VPAC2 receptors play distinct yet complementary roles in BV2 microglia. VPAC2 is critical for regulating survival, ER stress responses, and polarization under basal conditions, while VPAC1 is essential for adaptive responses to inflammatory stimuli such as LPS. These insights advance our understanding of microglial receptor signaling and may inform therapeutic strategies targeting microglial dysfunction in neurodegenerative diseases. Full article

The continuously growing diabetes population is a significant concern with type 2 diabetic retinal disease (T2DRD), which is a leading cause of permanent blindness. However, the underlying pathophysiological mechanism of T2DRD has not yet been fully understood. Pituitary adenylate cyclase-activating polypeptide (PACAP) was first isolated from the ovine hypothalamus based on its stimulating effect on the adenylate cyclase enzyme in anterior pituitary cells. PACAP38 (PACAP with 38 amino acids) activates anti-apoptotic pathways, inhibits pro-apoptotic signaling, and creates an anti-inflammatory environment in the retina. The aim of the present study was to test the possible retinoprotective effect of the topical administration of PACAP38 in a type 2 diabetic animal model induced by a high-fat diet and the intraperitoneally injected low-dose streptozotocin (STZ). Wistar rats were divided into four groups: the control, control + PACAP38, diabetes, and diabetes + PACAP38 groups randomly. Type 2 diabetes was induced with the combination of STZ (30 mg/kg) and a high-fat diet. All rats were treated topically two times a day for 16 weeks: the control + PACAP38 and diabetes + PACAP38 groups were applied with PACAP38 eye drops (1 µg/drop), while the control and diabetes groups were administered using vehicles (artificial tears). The diabetes model was validated by a fasting oral glucose tolerance test (OGTT) and C-peptide ELISA test. Animals were monitored during the whole experiment for the progression of the disease using electroretinography (ERG) and optical coherence tomography (OCT). Post-mortem immunohistochemistry and a vessel analysis were performed in the retina samples after 16 weeks. An OGTT, a C-peptide ELISA test, and the investigation of blood parameters proved the development of type 2 diabetes. Significant differences could be detected in visual function between the two diabetic groups at week 16 (in the a-wave, b-wave, and OP amplitudes), where the diabetes PACAP38-treated group was similar to the control ones. OCT measurements correlated with ERG data, where the total retinal thickness was preserved in the diabetes + PACAP38 group. PACAP38 also protected the microvascular structure in the retina. Topically administered PACAP38 has potent neuroprotective effects against type 2 diabetic retinal disease; therefore, it could be a promising therapeutic approach for the treatment of T2DRD. Full article

Actin, a key component of the cytoskeleton, undergoes significant structural and thermal changes in response to various regulatory factors, including the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP). In this study, we applied deconvolution analysis to previously obtained differential scanning calorimetry (DSC) data to resolve overlapping thermal transitions in G- and F-actin unfolding. Our findings reveal that PACAP38 and PACAP6-38 significantly alter actin stability, increasing structural cooperativity in G-actin while reducing monomer–monomer interactions in F-actin. These thermodynamic changes suggest a potential role for PACAP in modulating actin polymerization and depolymerization dynamics, contributing to cytoskeletal remodeling. Full article

The present study was designed to establish the distribution pattern and immunohistochemical characteristics of phoenixin-immunoreactive (PNX-IR) urinary bladder afferent neurons (UB-ANs) of dorsal root ganglia (DRG) in female pigs. The sensory neurons investigated were visualized with a retrograde tracing method using Fast Blue (FB), while their chemical profile(s) were identified using double-labelling immunohistochemistry with antibodies against PNX, calcitonin gene-related peptide (CGRP), calretinin (CRT), galanin (GAL), neuronal nitric oxide synthase (nNOS), pituitary adenylate cyclase-activating polypeptide (PACAP), somatostatin (SOM) and substance P (SP). Nearly half of UB-ANs contained PNX (45%), and the majority of such encoded sensory neurons were small in size (66%). The most numerous subpopulation of FB/PNX-positive neurons were those containing SP (71%). CGRP, GAL or PACAP were observed in a smaller number of PNX-containing UB-ANs (50%, 30% or 25%, respectively), while PNX-positive sensory neurons simultaneously immunostained with nNOS, CRT or SOM constituted a small fraction of all retrogradely-traced DRG neurons (DRGs; 15%, 6.5% or 1.6%, respectively). Furthermore, the numerical analysis of neurons expressing individual antigens, performed on 10 μm-thick consecutive sections, allows us to state that studied sensory neurons can be classified as neurons “coded” either by the simultaneous presence of SP/CGRP/PACAP/GAL, SP/CGRP/PACAP/NOS, SP/CGRP/PACAP/NOS/CRT and/or SP/CGRP/GAL/PACAP, or, as a separate population, those capable of SOM synthesis (SP/CGRP/SOM/PACAP/GAL-positive neurons). The present study reveals the extensive expression of PNX in the DRGs supplying to the urinary bladder, indicating an important regulatory role of this neuropeptide in the control of physiological function(s) of this organ. Full article