Protective Effect Of GPER1 In Hypothalamic Paraventricular Nucleus On Inflammatory Bowel Disease

Backgrounds and Purpose:Inflammatory bowel disease?IBD?is a group of clinically common chronic non-specific intestinal inflammatory diseases.However,the current clinical treatments are not effective,and most patients have recurrent episodes and prolonged unhealed,seriously affecting patients'quality of life.Previous studies have found that the hypothalamic-pituitary-adrenal axis?HPA axis?plays an important role in the"brain-intestinal"interaction,and the"brain-intestinal"interaction changes during the development of inflammatory bowel disease.The change drives the HPA axis,which in turn affects intestinal inflammation.GPER1?G protein-coupled estrogen receptor 1?is a novel transmembrane estrogen receptor,and there have been few studies on GPER1 and IBD.It is known that the neurons of the hypoventricular nucleus of hypothalamus?PVN?are responsible for the regulation of HPA axis activity,and studies have confirmed that GPER1 is highly expressed in the PVN region,but the regulation of the GPER1 receptor expressed by neurons in the PVN region in inflammatory bowel disease remains unclear.In the case of inflammatory stimuli in the peripheral intestine,how the central nervous system plays a regulatory role,and the aggravation or protection of inflammatory bowel disease is unknown.Therefore,we deeply studied the changes of GPER1 receptor in PVN neurons in the early stage of inflammatory bowel disease induced by Dextran sulfate sodium?DSS?and its effect on intestinal inflammation.Methods:?1?Using DSS to establish a mouse model of inflammatory bowel disease,weighing the body weight of mice;observing the pathological changes of colorectal tissue in mice by HE staining;detecting of IL-6 and IFN-?inflammatory factors in colorectal tissues of mice by Real-time PCR;measuring IL-6 expression in serum of mice by ELISA.?2?Immunofluorescence staining was used to identify the c-Fos activation,GPER1receptor expression and the co-standard ratio of PVN in the early stage of inflammatory bowel disease in rats.Western Blot technique was used to detect expression level of GPER1 in PVN area before and after IBD.?3?GPER1^-/-mice were constructed to compare the degree of intestinal inflammation in GPER1^-/-type and wild-type mice after inflammatory bowel disease modeling;Adeno-associated virus?AAV?against GPER1-shRNA was constructed to partly interfer the expression of GPER1 receptor in the PVN region of mice by stereotactic injection,comparing the degree of intestinal inflammation after inflammatory bowel disease in the control group and GPER1-shRNA interference group;colorectal distension?CRD?and Abdominal withdrawal reflex?AWR?scores were used to assess the severity of visceral pain in mice.Results:?1?DSS can successfully induce the state of inflammatory bowel disease in mice.Compared with the normal drinking group,the DSS model showed a significant decrease in body weight,a large number of inflammatory cells infiltrating the colorectal tissue,significant inflation and edema,structural damage,and elevated inflammatory factors such as IL-6 and IFN-?also increased significantly.?2?PVN neurons can be activated in the early stages of intestinal inflammation and are mostly GPER1 positive.Compared with the normal drinking group,the expression of c-Fos in the PVN area of the DSS model was significantly increased,the expression of GPER1 was significantly increased,and the co-standard ratio increased significantly.?3?Systemic GPER1 gene knockout and GPER1 local knockout in PVN area can aggravate the degree of intestinal inflammation in mice,but the effect on the severity of visceral pain is weak.After 1 week of DSS modeling,compared with wild-type mice,the degree of intestinal inflammation in GPER1^-/-mice was significantly aggravated,the weight loss was more significant,and the survival rate was greatly reduced.Local interference in the expression of GPER1 receptor in the PVN region also aggravated the degree of intestinal inflammation.There was no significant difference in AWR scores between GPER1^-/-mice,PVN-region GPER1 knockout mice and wild-type mice.Conclusion:GPER1-positive neurons in the PVN region can be activated and protected in the early stage of DSS-induced inflammatory bowel disease,which may be an important mechanism for the central nervous system to regulate peripheral intestinal inflammation for self-protection,as well as provide new target for clinical treatment of IBD.