The Study On The Expression Of Extrasynaptic GABAA Receptors In Specific Brain Regions During Different Phase Of Estrus Cycle In Rodents

The estrogen and progesterone during the female reproductive cycle change cyclically,especially during pregnancy and postpartum,this lead to a variety of emotionaldisorder and clinical symptoms for women. The mental disease above for women areall triggered by the fluctuations of estrogen, progesterone and other ovarian steroidhormones over women reproductive cycle. Progesterone and GABAA-conditioningsystems play a major role in these clinical symptoms. But the understanding of therelationship between regulation of steroidal hormones to central nervous system andsuch central nervous system depression is not yet unified, existing research isinsufficient to reveal the substance of such diseases. Analysis the relationship betweenthe hormone and the female emotional changes can provide new theoretical basis forthe mechanism of the alerteration about hormonal and emotion. From this point,thisexperiment mainly study the change of indicators related to different reproductivecycle of rodents,analysis the relationship between the level of progesterone andextrasynaptic GABAA receptor subunit δ expression in different brain region.PartⅠ：The study on the expression of extrasynaptic GABAAreceptors incerebral cortex and hippocampus during different phase of estrus cycles infemale miceObjective In this study, we mainly expore the change of indicators related tomice different reproductive cycle,explore the alteration of animal behavior overmouse estrus cycle and study the expression and functional alterations of GABAA receptor in cerebral cortex and hippocampus during mouse estrus cycle.Methods Determine the estrous cycle accurately using the vaginal smearmethod,the mice with well-established ovarian cycles were used.Two stages of theestrous cycle were chosen for comparison: the estrus phase and the diestrus phase.Using the Elisa kit to detect the serum concentrations of estrogen and progesterone.Detect the alterations of the behavior during mouse estrus cycle using the elevatedplus maze（EMP）.Immunohistochemical method was used to marker the differenceexpression of subunit δ in the mice during estrus and diestrus.Analysis therelationship between the level of progesterone and extrasynaptic GABAA receptorsubunit δ expression.Results Elisa result shows that the levels of serum estrogen in estrus（185.48±35.42pg/ml）were significantly higher than the diestrus group（157.00±21.30pg/ml,P<0.05）. But, the levels of estrus serum progesterone in estru（s6.02±2.20ng/ml）aresignificantly lower than the diestrus group（12.47±1.89ng/ml,P <0.05）. The resultsof elevated plus maze（EMP）shows that the time and entry of the mouse over diestrusstage in the open arms and center are significantly more than estrus group（P＜0.05）,however the total movements in the open arms、center and close arms is notdifference. Immunohistochemistry showed that the positive expression of GABAAreceptor subunit δ during diestrus(28.93×10^-3±4.92×10^-3)when progesterone washigh and estrogen was low was stronger compared with estrus(18.89×10^-3±3.74×10^-3)significantly in mouse hippocampus（P＜0.05）; however, in the mouse cerebralcortex, the positive expression of subunit δ was strong in both groups,but thedifference between the diestrus groups(39.84×10^-3±2.97×10^-3)and the estrusgroups(37.31×10^-3±1.13×10^-3) was not significant（P>0．05）. The Changes ofhippocampus subunit δ IOD values over the diestrus and estrus is significantlycorrelated with progesterone concentration. The correlate coefficient is0.9924. Conclusion1.The average estrous cycle of C57BL/6J mice is5.3days, the miceblood estrogen concentration in the estrus group is higher than that in the diestrusgroup, blood progesterone concentration in diestrus group is higher than the estrusgroup, estrogen and progesterone concentration change followed by the ovarian cycle.2.Under physiological condition of mice,the subunit δ of the GABAA receptorexpress differently in specific brain regions over the different reproductive cyclefollowed by fluctuation of estrogen and progesterone levels,and extrasynapticsubunit δ express increase paralleled with progesterone concentrations,their levelvolatility can affect emotions and behavior in mouse.The extrasynaptic GABAAreceptor subunit δ has no significant difference in cerebral cortex over diestrus andestrus.4. Behavioral experiment shows that: in the elevated plus maze,the time andthe entries into the open arm of diestrus group is greater than the estrus group,theadaptability of diestrus group to environment increases.PartⅡ:The study on the expression of extrasynaptic GABAA receptors inhippocampus, dentate gyrus, amygdala during different phase of estrus cycles infemale ratObjective Definite the alteration of extrasynapse GABAA receptorexpression followed by the ovarian steroid hormone.and the correlation with thefluctuation of the ovarian steroid hormone. Methods The rats with well-establishedovarian cycles were used.Two stages of the estrous cycle were chosen for comparison:the estrus phase and the diestrus phase. Using the Elisa kit to detect the serumconcentrations of estrogen and progesterone.Immunohistochemical method were usedto marker the difference expression of subunitδin the rat during estrus anddiestrus.Analysis the relationship between the level of progesterone and extrasynapticGABAA receptor subunit δ expression. Results The levels of estrus serumestrogen（42.51±2.42） were significantly higher than the diestrus group（23.17±1.45） （P<0.05）. But, the levels of estrus serum progesterone（7.41±2.86） are signifycantlylower than the diestrus group（10.31±1.74,P<0.05）. In the rat hippocampus dentategyrus，we found that the positive expression of GABAA receptor subunitδin diestrus(105.47×10^-3±4.73×10^-3) were significantly higher than the estrus group(79.23×10^-3±2.89×10^-3,P<0.05). In the rat amygdala，we also found that the positiveexpression of GABAA receptor subunitδin diestrus (93.51×10^-3±3.54×10^-3) weresignificantly higher than the estrus group(58.92×10^-3±1.47×10^-3,P<0.05).The IODvalue of subunit δ-positive increase in hippocampus dentate gyrus、amygdala wasparallel to the progesterone concentration increase during diestrus and estrus. Bycorrelation analysis, we found a linear correlation between two variables in a certainrange, the correlation coefficients were respectively R=0.9866、 R1=0.9876.Conclusion The high level of progesterone during diestrus can cause high expressionof extrasynaptic GABAA receptor subunit δ in hippocampus dentate gyrus andamygdala.