Effects Of Estrus Cycle On Cortisol And Brain C-fos Expression In Restraint-stressed Rats

Object:To investigate how estrus cycle influenced serum cortisol and cerebral c-fos protein expression after exposure to acute restraint stress.Methods:1. All female rats were gonadally intact and were separated into groups based on stage of estrus cycle decriminated by vaginal smear. 2. Female rats of stressed group were sacrificed 60 minutes following the onset of restrainted stress. 3. Serum specimen were prepared for detection of estradiol, progesterone and cortisol. 4. Brains were prepared for immunocytochemical detection of c-fos protein.Result:1. Serum cortisol was in high level during proestrus when estradiol is high both in retraint stressed group and unstressed group.Contraversly,it was low in diestrus when estrodial level is low.2.C-fos protein expression was significantly lower during proestrus than diestrus in the region of hippocampal (CA1,CA2,CA3),cortex (PC,FC )and lateral habenula after exposure to 60 min-restraint stress.In the medial habenula, c-fos protein exprssion of stressed rats was higher than unstressed, but there is no significance according to stage of estrus.Discussion:As manifested by epidemiological investigation, a number of affective disorders linked to impaired HPA activity (i.e. major depression,post-traumatic stress disorder (PTSD),anorexia nervosa,and panic disorders )are more commonly diagnosed in females than males.It indicates that there is obviously differences in gender during stress event. These may possiblely contribute to the menstrual cycle of females,and there is obviously fluctuation for estradiol...