| Objective: To investigate the effect of the orexin-A on nycterohemeral food intake in rats.Methods: Adult Wistar rats were implanted into the lateral ventricle.Wistar rats were randomly divided into three parts: single lateral ventricle injection,continuous side Intraventricular injection and peripheral injection.Single ventricle injection was randomly divided into 8: 00 Am lateral ventricle injection 2.5 nmol/10 ?L Orexin-A,8: 00 Am lateral ventricle microinjection 7.2 nmol/10 ?L Orexin-A,8: 00 Am lateral ventricle microinjection 24.5 nmol/10 ?L Orexin-A,8: 00 Am Intraventricular microinjection 10 ?L NS,18: 00 Intraventricular microinjection 24.5 nmol/10 ?L Orexin-A,18: 00 Intracerebroventricular microinjection 10 ?L NS,24: 00 lateral ventricle Microinjection 24.5 nmol/10 ?L Orexin-A,24: 00 Intracerebroventricular microinjection 10 ?L NS,8: 00 Am Intracerebroventricular injection Orexin-A + Intracerebroventricular microinjection 24.5 nmol/10 ?L Orexin-A,8: 00 Am Intracerebroventricular injection Orexin-A + lateral ventricle microinjection of 10 ?L NS.The rats were randomly divided into two groups: 18 nmol/10 ?L Orexin-A and 10 ?L NS were injected intraperitoneally at 8:00 pm and 15:00 pm daily for 8 days The rats were divided into tail vein by intravenous injection of 5 mg / kg/200 ?L Orexin-A,200 ?L NS at the end of the tail vein,18 nmol/50 ?L orexin-A subcutaneously,50 ?L NS subcutaneously for 8 days,During the administration period,the rats were given plenty of diet and water.The food intake and the corresponding biochemical indexes were measured and compared in 24 hours.Results:Compared with control group,in the light phase(08:00),the single microinject orexin-A into ICV dose-dependently increased food intake following the next 4 h in rats(P<0.05~0.01);compared with control group,the food intake of rats in 18:00-22:00,22:00-18:00 and 18:00-18:00 was no significant change after ICV infusion of orexin-A in 6:00 pm(18:00).in the dark times(24:00),administered ICV with orexin-A can inhance the accumulated food intakes in the next 4 h,but this effect was disappeared after administered 4 h(P>0.05).In the light phase(08:00),the food intakes of rats in 4 h was increased significantly after a single administered ICV with orexin-A(P>0.05),the food intakes of rats in the next 8 h was decreased significantly(P<0.05).However,the total 24 h food intake have no significant change(P>0.05).Continuous administered ICV with orexin-A for two days significantly increased the food intakes during the light phase(08:00-18:00,P<0.05),and reduced it during the dark phase(18:00-08:00,P<0.05).Continuous administered ICV with orexin-A for eight days significantly decreased the total 24 h food intakes(P<0.05),but the food intakes was increased significantly(P<0.05)during the light phase(08:00-18:00),and the food intakes was decreased significantly(P<0.05)during the dark phase(18:00-08:00).The level of the temperature of brown adipose tissue,peripheral blood glucose,plasma leptin and other indexes were not change after ICV infusion of orexin-A.Conclusions: The regulation of Orexin-A on food intake in rats was circadian rhythm. |
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