ALTERATION OF PHOSPHORYLATED ERK1/2 IN THE RAT BRAIN INDUCED BY WATER RESTRICTION / 解剖学报

ABSTRACT

Objective To investigate the effect of stress induced by water restriction on the level of phosphorylated(ERK1/2) in rat brain. Methods Fifty-eight male Wistar rats were used and randomly divided into control group(C,n=4) and three experimental groups TW(drinking at scheduled time),EB(empty bottle stimulus),WR(restricted water drinking),which were subdivided into three subgroups by time as 3d,7d, 14d(n=6 for each).In C group,water was freely accessed to the animal for one week.In the experimental groups the water supply was restricted following a week of accommodation and the other week for timed water supply training.In TW group,the water was supplied twice a day and 10 min for each in a fixed time. In EB and WR groups,the water was served only once a day for 10 min,and in the other scheduled time for water supply only an empty bottle without water was provided in the EB group and water was limited in the WR group.All the animals were deeply anesthetized 1h after the last stimulus and transcardially infused,then the brains were cut into free-floating sections and processed for immunohistochemical staining of pERKI/2 with ABC method.The expression of pERK1/2 positive staining was measured with image analysis system. Results The area of phosphorylated ERK1/2 was significantly increased in many brain structures,especially in paraventricular hypothalamic nucleus(PVN),supraoptic nucleus(SON),ventrolateral septum(LSV),medial amygdaloid nucleus(MeA),central amygdaloid nucleus(CEA) and nucleus of solitary tract(NTS) in TW,EB and WR group compared with C group.The expression of phosphorylated ERK1/2 in SON,LSV, MeA and CeA in EB and WR group were higher than that in TW group;pERK1/2 expression of LSV,MeA,CeA and NTS in EB group increased and went down more early and quickly than that in WR group.The response of phosphorylated ERK1/2 was dependent on both stimulus methods and time in all the nuclei mentioned above except PVN,in which only the stimulus time was related. Conclusion The level of pERK 1/2 was significantly altered in PVN,SON,LSV,MeA,CeA and NTS following stimulation of water restriction.The results indicate that the activated nuclei in the brain by physical and psychological stressors are different.