| Objective Stress is a common external factor in daily life,which can lead to physiological and behavioral disorders,and even affect the diet pattern.The feedback regulation system of stress includes the regulation of various feedback and related peptides in central and peripheral nervous system.Orexin-A(OXA)is one of the important neuropeptides secreted by the hypothalamus,which is closely related to food intake and obesity.It has been reported that the number of orexinergic neurons in LHA decreased significantly in male Wistar Kyoto rats with chronic psychological stress symptoms.In addition,compared with the healthy people,the level of oxa in cerebrospinal fluid of the patients with mood disorder and depression who suffered from mental illness for a long time was significantly lower.The hypothalamus contains many important nuclei related to food intake,which are closely related to the emotion center,such as the amygdala.The amygdala is an important center for emotion generation,emotion recognition and emotion regulation.It includes the central amygdala(CEA),the basolateral amygdala(BLA)and the basolateral amygdala(BMA).There is a fiber connection between CEA and hypothalamus,which is involved in feeding regulation of hypothalamus.The purpose of this study is to establish chronic unknown psychological stress(cums)model rats,and to observe the effect and potential mechanism of CEA orexin-A on feeding behavior,gastric acid secretion,gastric motility and gastric emptying of chronic psychological stress rats.The purpose is to provide reliable experimental basis for the prevention and treatment of gastrointestinal dysfunction caused by clinical stress disorder.Methods(1)To construct the chronic psychological stress model of rats: randomly select the stress factors: the rats fasted for 24 hours,or banned water for 24 hours,or used damp pad for 24 hours,or forced the rats to swim for 5 minutes at 4 ?,or the rats were in the day and night reversed environment(8:00-20:00 dark,20:00-8:00 light),or the cage tilted at 45 ° angle for 24 hours.From 8:00 to 9:00 a.m.every day,rats in cums + NS group and rats in cums + oxa group were randomly given one of the above stimuli,each of which was only given once a week.The body weight of rats was measured at the end of 1,3,5 and 7 weeks.Rats in the pseudo chronic psychological stress group were not treated with random stress factors,and other conditions were the same as those in the chronic psychological stress group.After 49 days,if the body weight of the CUMS model group rats is more than 30% lower than that of the Sham group,the model is considered successful.(2)Experimental group: Sprague Dawley(SD)male rats were randomly divided into 4 groups:(1)normal saline group(sham + NS group): normal rats were injected with 0.5 ? l ns;(2)chronic psychological stress rats were injected with 0.5 ? l ns;(3)normal rats were injected with 2.0 nm / 0.5 ? l oxa.(4)orexin-A group(cums + oxa group)of chronic psychological stress rats: CEA was injected with 2.0 nm / 0.5 ? l oxa.(3)The rats were catheterized in the CEA area,and then microinjected with oxa into the CEA nucleus through cannula.The changes of food intake and cumulative food intake in 3 hours and 0-1h,1-2h,2-3H in normal and psychological stress rats were observed.(4)Oxa was microinjected into CEA nucleus and the gastric acid secretion of normal and psychological stress rats was observed by pylorus ligation.(5)Stress sensor was implanted in the serous layer of gastric antrum and oxa was injected into the CEA nucleus to observe the changes of gastric motility in normal and psychological stress rats.(6)Oxa was microinjected into CEA nucleus to observe the effect on gastric emptying in normal and psychological stress rats.(7)The expression of ox-1r immunoreactive cells in CEA of chronic psychological stress rats and healthy rats was observed and compared by immunohistochemistry.(8)Western blot was used to observe and compare the expression of ox-1r protein in CEA of chronic psychological stress rats and healthy rats.(9)The binding ability of oxa and ox-1r in CEA of chronic psychological stress rats and healthy rats was observed and compared by radioligand receptor binding assays(RBA).Results(1)The food intake of 0-1h,1-2h and 2-3H and the cumulative food intake of 3 hours were significantly reduced in rats with chronic psychological stress,but the food intake of the first hour was significantly reduced compared with that of the second hour(P < 0.05).In normal rats,the food intake and accumulated food intake of rats at 0-1h,1-2h and 2-3H after CEA microinjection were significantly increased,but the food intake of rats at the first hour was more significant compared with that of rats at each hour.In cums rats,the food intake of 0-1h,1-2h and 2-3H,and the cumulative food intake of 3 hours were significantly reduced after CEA microinjection of oxa.Compared with the rats in cums + NS group,the food intake and accumulated food intake of 0-1h,1-2h and 2-3H significantly increased after CEA microinjection.Compared with normal rats,the first hour feeding effect of CEA microinjection of oxa in rats with chronic psychological stress was more significant(P < 0.05).(2)The results showed that compared with normal rats,the gastric acid secretion of chronic psychological stress rats decreased significantly(P < 0.05).Compared with sham + NS group,the gastric acid secretion of normal rats increased significantly after CEA microinjection of oxa(P < 0.05).Compared with rats in cums + NS group,the gastric acid secretion of rats in cums group increased significantly after CEA microinjection of oxa(P < 0.05).Compared with normal rats,the increase of gastric acid secretion of chronic psychological stress rats by CEA microinjection was more significant(P < 0.05).(3)The results showed that compared with normal rats,the percentage of gastric motility index(MI)of chronic psychological stress rats decreased(P < 0.05).In normal rats(sham + NS group)treated with oxa microinjection of CEA,the% Mi of rats increased significantly.Compared with rats in cums + NS group,the% Mi of rats in cums group increased significantly after CEA microinjection of oxa(P < 0.05).Compared with the normal rats,the gastric motility of chronic psychological stress rats increased more significantly by CEA microinjection of oxa(P < 0.05).(4)The effect of CEA microinjection of oxa on gastric emptying of rats with chronic psychological stress showed that the gastric emptying rate of rats with chronic psychological stress was significantly lower than that of normal rats(P < 0.05).Compared with sham + NS group,the gastric emptying of normal rats(sham + oxa group)increased significantly after CEA microinjection(P < 0.05).Compared with rats in cums + NS group,the gastric emptying rate of rats in cums group increased significantly after CEA microinjection of oxa(P < 0.05).Compared with normal rats,the gastric emptying effect of CEA microinjection of oxa in rats with chronic psychological stress was more significant(P < 0.05).(5)The expression of CEA ox-1r immunoreactive neurons in cums rats was significantly higher than that in normal rats(P < 0.05).(6)The expression of CEA ox-1r in cums rats was significantly higher than that in normal rats(P < 0.05).(7)The results of radioligand receptor binding analysis showed that the binding capacity of oxa and ox-1r in CEA of cums rats was significantly enhanced compared with that of normal rats(P < 0.05).Conclusion Chronic psychological stress can significantly reduce the stage and cumulative intake of rats;at the same time,gastric acid secretion,gastric motility and gastric emptying are significantly reduced or weakened;CEA exogenous orexin-A can effectively alleviate the above negative effects caused by chronic psychological stress in rats,which may be related to the increase of ox-1r expression in CEA and the increase of ox-1r and oxa binding capacity. |
PDF Full Text Request