Experimental study of the role of hypothalamopituitary system in control of pain

本文用热板法研究了大鼠下丘脑-垂体系统在痛控制中的作用，并着重观察了血清促肾上腺皮质激素释放因子（CRF）的作用。ACTH水平和疼痛阈值。1.在20只大鼠急性期首次静脉注射CRF，并将其对痛阈的影响与血清ACTH水平进行比较，ACTH来源于垂体中β-内啡肽的同一前体。10只大鼠经颈静脉注射CRF，共7天，每次170 μ g/1.7ml，皮下包埋渗透泵。急、慢性静脉注射CRF对痛阈无明显影响。雨阈与血清浓度无关。促肾上腺皮质激素（ACTH）水平采用RPA法测定.将2 μ g/lmul的CPF微量注射到10只切除或不切除垂体的大鼠下丘脑室旁核（PVN）内，对痛阈无任何影响.将吗啡微量注射到1.1只切除或不切除垂体的大鼠下丘脑PVN内，均使痛敏感性明显降低。提示CRF在下丘脑-垂体系统的痛觉控制机制中不起重要作用。而PVN可能是下丘脑-垂体系统控制疼痛的重要部位。

The role of hypothalamopituitary system in control of pain was studied in rats by the hot-plate method, being with special reference to the effect of corticotrophin releasing factor(CRF) on the serum. ACTH level and on the pain threshold.1. CRF was first given intravenously in acute stage in 20 rats, and the effect of the pain threshold was compared with the serum level of ACTH, which is derived from the same precursor of beta-endorphine in the pituitary gland. Then CRF was chranically injected into the jugular vein of 10 rats, for 7 days and totally 170 mug/1.7 ml, by way of an osmotic mini-pump which was embedded subcutaneously. Results of acute and chronic intravenous injection of CRF didn't alter the level of threshold of pain. Moreover there was no relationship between the rain threshold and the serum. ACTH level, which was measured by RPA method.2. CPF was microinjected as much as 2 mug/lmul into the paraventricular nucleus of hypothalamus(PVN) of 10 rats with or without hypophysectomy, which didn't produce any change in pain threshold.3. Morphine was microinjected into the PVN of hypothalamus of 1.1 rats with or without hypophysectomy, which resulted in marked diminution of pain susceptibility. These findings suggested that CRF did not play the important role in mechanism of pain control of hypothalaipopituitary system. However, PVN appeared to be the important site in control of pain in hypothalamopituitary system.