FACILITATION AND FEEDBACK IN THE HYPOTHALAMO-PITUITARY-ADRENAL AXIS DURING FOOD RESTRICTION IN RATS
FACILITATION AND FEEDBACK IN THE HYPOTHALAMO-PITUITARY-ADRENAL AXIS DURING FOOD RESTRICTION IN RATS
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DOI：
10.1111/j.1365-2826.1993.tb00537.x
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发表时间：
1993-12-01
影响因子：
3.2
通讯作者：
MORMEDE, P
中科院分区：
文献类型：
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作者：
GARCIABELENGUER, S;OLIVER, C;MORMEDE, P
大鼠限食至50%自由摄入量4周后，血浆皮质酮水平升高，肾上腺重量无任何变化，且无交感神经系统激活迹象（通过肾上腺中酪氨酸羟化酶和苯乙醇胺N-甲基转移酶活性测定）。血浆皮质酮水平通过添加35%的卡路里作为糖而正常化。因此，更详细地研究了随意喂食大鼠和喂食对照动物摄入量85%或50%的动物中的肾上腺皮质轴活动（皮质酮水平的昼夜循环、ACTH和皮质酮对CRF激发的反应），就在关灯之前，以保持食物摄入的昼夜节律。食物限制到85%并没有改变平均血浆皮质酮水平，但锐化皮质酮在晚上测量的峰值，表明肾上腺皮质轴是更敏感的内源性信号负责其昼夜周期的活动。事实上，促肾上腺皮质激素对CRF的反应也增加了。50%的食物限制方案增加了平均皮质酮水平和衰减的日/夜差异，高皮质酮水平保持在一整天。然而，促肾上腺皮质激素对CRF的反应与自由进食大鼠的反应没有差异，但皮质酮反应较低，证实肾上腺对促肾上腺皮质激素敏感性降低。结果进行了讨论，在抑制/激活机制和内分泌/神经的影响，在每个层次的下丘脑-垂体-肾上腺轴之间的平衡，这取决于水平的食物剥夺。
After 4 weeks of food restriction to 50% of ad libitum intake in rats, plasma corticosterone levels were increased, without any change in adrenal weight, and with no evidence of sympathetic nervous system activation (as measured by Tyrosine Hydroxylase and Phenylethanolamine N-Methyl Transferase activities in the adrenal gland). Plasma corticosterone levels were normalized with the addition of 35% of the calories as sugar. The adrenocortical axis activity was therefore investigated in more detail (nycthemeral cycle of corticosterone levels, ACTH and corticosterone response to a CRF challenge) in ad libitum fed rats and in animals fed 85% or 50% of the intake of the control animals, just before switching the lights off in order to maintain the diurnal rhythm of food intake. Food restriction to 85% did not change mean plasma corticosterone levels but sharpened the peak of corticosterone measured in the evening, indicating that the adrenocortical axis is more sensitive to the endogenous signals responsible for its diurnal cycle of activity. Indeed, the ACTH response to CRF was also increased. A 50% food restriction regimen increased mean corticosterone levels and attenuated the day/night difference, with high corticosterone levels maintained throughout the day. However, the ACTH response to CRF was not different from that measured in ad libitum fed rats, but the corticosterone response was lower, confirming that the adrenal gland is hyposensitive to ACTH. The results are discussed in terms of the balance between inhibiting/activating mechanisms and endocrine/neural influences at each level of the hypothalamo-hypophyso-adrenal axis, depending on the level of food deprivation.