Studies on Hypothalamic CRHmRNA

促肾上腺皮质激素释放激素(CRH)和精氨酸加压素(AVP)是ACTH最重要的生理性释放因子。检测CRHmRNA和AVPmRNA的基因表达。用半定量原位杂交组织化学方法检测下丘脑视上核(SON)和室旁核(PVN)内AVPmRNA的表达。大鼠双侧肾上腺切除后1周，血浆ACTH水平显著升高，中点CRH水平下降，中点AVP水平升高。高渗盐水(2%)灌胃3d后，PVN和ME的CRH水平与对照组相比无明显差异。血浆皮质酮、AVP显著升高。垂体后叶AVP含量显著降低，PVN和SON中AVPmRNA表达显著增加，缺水使PVN和SON中AVPmRNA表达增加。血浆ACTH、皮质酮、AVP和渗透压显著升高。下丘脑下丘脑、下丘脑和下丘脑组织中AVPmRNA的浓度无显著差异。血浆ACTH和皮质酮水平显著升高，而血浆AVP和渗透压无明显变化。结果表明，食物剥夺刺激了下丘脑肾上腺轴，AVP的表达下降是由自身的食物剥夺引起的，AVP可能是肾上腺皮质功能不全、高渗盐水和缺水时ACTH升高的部分原因，但在食物剥夺时不起作用。

Corticotropin Releasing hormone (CRH) and Arginine Vaso-Pressin (AVP) are the most important physiological ACTH releasing factors. Gene expression of CRHmRNA and AVPmRNA were investigated. Levels of AVPmRNA in the hypothalamic Supra-Optic Nucleus (SON) and the Para-Ventricular Nucleus (PVN) were determined by semiquantitative in situ hybridization histochemistry. However, we failed to detect CRHmRNA levels by in situ hybridization technique in spite of great efforts.In bilaterally adrenalectomized rats, plasma ACTH levels increased significantly, CRH levels in the Median Eminence (ME) decreased and AVP levels in the ME increased one week after surgery. AVPmRNA in the PVN and SON increased significantly.In the rats given hypertonic saline (2%) for 3 days, CRH levels in the PVN and ME did not differ from those in the control rats. Plasma corticosterone, and AVP increased significantly. AVP contents in the posterior pituitary decreased and AVPmRNA in the PVN and SON increased significantly.Water deprivation increased AVPmRNA in the PVN and SON. Plasma levels of ACTH, corticosterone, AVP and osmolality were significantly elevated. The concentration in the posterior pituitary, ME and the remaining hypothalamic tissue did not differ significantly.Food deprivation decreased AVPmRNA in the PVN and SON. Plasma levels of ACTH and corticosterone were greatly elevated, while plasma AVP and osmolality did not differ significantly. The results indicated that food deprivation stimulated the pituitaryadrenal axis and that a reduction in AVPmRNA levels in food deprived rats was caused by food deprivation per se.According to these observations, AVP may be at least partly responsible for ACTH elevation in adrenal insufficiency, hypertonic saline administration and water deprivation but not in food deprivation.