Effects of pituitary adenylate cyclase activating polypeptide on CD4^+/CD8^+T cell levels after traumatic brain injury in a rat model

BACKGROUND:The effect of pituitary adenylate cyclase activating polypeptide(PACAP)during traumatic brain injury(TBI) and whether it can modulate secondary injury has not been reported previously.The present study evaluated the potential protective effects of ventricular infusion of PACAP in a rat model of TBI.METHODS:Male Sprague Dawley rats were randomly divided into 3 treatment groups(n=6,each):sham-operated,vehicle(normal saline)^+TBI,and PACAP^+TBI.Normal saline or PACAP(1 ug/5uL) was administered intracerebroventricularly 20 minutes before TBI.Right parietal cortical contusion was produced via a weight-dropping method.Brains were extracted 24 hours after trauma.Histological changes in brains were examined by HE staining.The numbers of CD4^+ and CD8^+ T cells in blood and the spleen were detected via flow cytometry.RESULTS:In injured brain regions,edema,hemorrhage,inflammatory cell infiltration,and swollen and degenerated neurons were observed under a light microscope,and the neurons were disorderly arrayed in the hippocampi.Compared to the sham group,average CD4^+ CD8" lymphocyte counts in blood and the spleen were significantly decreased in rats that received TBI^+vehicle,and CD4^+ CD8^+ were increased.In rats administered PACAP prior to TBI,damage was attenuated as evidenced by significantly increased CD4^+,and decreased CD8^+,T lymphocytes in blood and the spleen.CONCLUSION:Pretreatment with PACAP may protect against TBI by influencing periphery T cellular immune function.

基于PACAP-cAMP信号通路研究电针治疗骶上脊髓损伤后逼尿肌反射亢进型膀胱的效应机制

Objective:To elucidate the underlying mechanism and effect of electroacupuncture(EA)on the neurogenic bladder following suprasacral spinal cord injury(ssCI).A rat model of detrusor hyperreflexia after SsCI was established to examine the urodynamics,detrusor muscle tissue morphology,the protein and mRNA expression levels of pituitary adenylate cyclase activating peptide(PACAP)and its receptor PAC1R,and cyclic adenosine monophosphate(cAMP)content in the detrusor muscle with a focus on the PACAPcAMP signaling pathway.Method:A total of 72 female SD rats were randomized into control group and sham operation group(n=12 per group)by using a random number table.The remaining 48 rats were established into the model of detrusor hyperreflexia after SsCI.After successful modeling,these rats were randomly assigned to model,EA,and EA+PACAP6-38 groups(n=12 per group).The unsuccessful modeled rats were used for exploratory observation.For the rats in EA group,"Ciliao(BL32)""Zhongji(CV3)",and"Sanyinjiao(SP6)"were needled and stimulated by EA.The PACAP receptor antagonist PACAP6-38 was administered intraperitoneally in the EA+PACAP6-38 group before EA,and EA was applied for seven consecutive days.After treatment,the urodynamics of the rats were analyzed,and hematoxylin and eosin staining was used to examine rat bladder detrusor tissue morphology.The expressions of PACAP-38 and PAC1R were detected by immunohistochemistry and Western blot.The mRNA expression levels of PACAP-38 and PAC1R were examined by RT-qPCR,while cAMP content was detected by ELISA.Results:(1)Compared with sham operation group,it was exhibited disarray in the transitional epithelium cells of the bladder in the modeled rats.The intercellular space was significantly widened,accompanied by inflammatory cell infiltration and noticeable tissue edema.Both the bladder initial pressure and leak point pressure of the rats were higher(P<0.01),whereas the maximum cystometric capacity and bladder compliance were lower(P<0.01).The protein and mRNA expression levels of PACAP-38 and PAC1R in the detrusor muscle,together with the cAMP content,were lower(P<0.05).(2)Compared with the model rats,the EA group showed reduced inflammatory response in the detrusor muscle tissue,with decreased monocyte infiltration and less severe tissue edema.The bladder smooth muscle cells exhibited increased integrity,and there was decreased cellular tissue edema,inflammatory cell infiltration,and fibroplasia.The bladder initial pressure and leak point pressure were lower(P<0.05),while the maximum cystometric capacity and bladder compliance were higher(P<0.01).The protein and mRNA expression levels of PACAP-38 and PAC1R in the detrusor muscle,along with the cAMP content,were higher(P<0.05).(3)Compared to the EA group,the EA+PACAP6-38 group showed a less organized arrangement of muscle fibers in the detrusor muscle tissue,larger intercellular space,monocyte infltration,and considerable tissue edema.The changes in bladder initial pressure and leak point pressure were not significant(P>0.05),while the maximum cystometric capacity and bladder compliance were lower(P<0.05).The changes in the protein and mRNA expressions of PACAP-38 within the detrusor muscle were not signifcant(P>0.05),whereas the protein and mRNA expressions of PAC1R were reduced(P<0.05),and the cAMP content within the detrusor muscle was lower(P<0.05).Conclusion:EA can ameliorate the uninhibited contractile condition of the detrusor muscle in the bladder following SSCI.By mediating the PACAP-cAMP signaling pathway,it reduces the pathological damage to the detrusor muscle,thereby improving bladder function.

Neuroprotective Effects of Brain-Gut Peptides: A Potential Therapy for Parkinson’s Disease

Parkinson's disease(PD) is the second most common neurodegenerative disease and is typically associated with progressive motor and non-motor dysfunctions.Currently, dopamine replacement therapy is mainly used to relieve the motor symptoms, while its long-term application can lead to various complications and does not cure the disease. Numerous studies have demonstrated that many brain-gut peptides have neuroprotective effects in vivo and in vitro, and may be a promising treatment for PD. In recent years, some progress has been made in studies on the neuroprotective effects of some newly-discovered braingut peptides, such as glucagon-like peptide 1, pituitary adenylate cyclase activating polypeptide, nesfatin-1, and ghrelin. However, there is still no systematic review on the neuroprotective effects common to these peptides. Thus,here we review the neuroprotective effects and the associated mechanisms of these four peptides, as well as other brain-gut peptides related to PD, in the hope of providing new ideas for the treatment of PD and related clinical research.