急性或慢性应激对高热量饲料喂养大鼠HPA轴的影响

Effect of acute or chronic stress on the hypothalamic-pituitary-adrenal axis function in high calorie diet fed rats

目的比较正常饲料或高热量饲料喂养大鼠,在有或无慢性应激长期刺激后,再给以一次急性应激前后下丘脑-垂体-肾上腺轴(HPA轴)功能的改变。方法雄性wistar大鼠分为正常饲料组(对照组)、高热量饲料(HCD)组、正常饲料慢性应激(CS)组及高热量饲料慢性应激(HCD+CS)组。5周后,首先检测血脂并进行胰岛素敏感性试验;然后再给以一次急性应激,检测急性应激前后血液促肾上腺皮质激素(ACTH)、皮质酮及血糖浓度的改变。结果与对照组比较,HCD及HCD+CS组出现明显的血脂异常,但CS组无明显改变;三组均出现明显的胰岛素抵抗(IR)及HPA轴激活,但HCD+CS组变化更明显。急性应激后,与对照组一样,三组HPA轴可进一步激活,但HCD组激活程度明显高于其它组。血糖变化与HPA轴激活相对应。结论长期高热量饲料喂养可明显提高因长期慢性应激或急性应激引起的HPA轴激活,尤其可使急性应激后的HPA轴激活程度大大提高。这种HPA轴的激活,与血糖升高、IR、血脂异常相对应。

Aim To explore the effects of combination of high calorie diet and chronic stress on hypothalamic-pituitary-adrenal axis （ HPA axis） before or after an acute stress. Methods Male rats were divided into four groups：control group（ Control）, high calorie diet group （ HCD）, chronic stress group （ CS）, high calorie diet plus chronic stress group （ HCD ＋ CS）. After 5 weeks, insulin tolerance test was performed, meanwhile blood fat, glucose, adrenocorticotropie hormone（ACTH） and corticosterone were assessed. After treated with an acute stress, serum glucose, adrenocorticotropic hormone（ACTH） and eorticosterone of the rats were assessed. Results The HCD and HCD ＋ CS group showed evident dyslipidaemia, and all the three groups with special treatment showed evident insulin resistance（IR） and HPA axis activation, especially in HCD ＋ CS group. After the acute stress, the HPA axis function in all the four groups can be further activated, especially in HCD group. Further more, the blood glucose was in accordance with the HPA axis activation. Conclusion High calorie diet can markedly elevate the HPA axis activation induced by chronic stress or acute stress, especially by acute stress. The HPA axis activation was in accordance with the rise of blood fat, glucose and IR.