Willoughby J O, Terry L C, Brazeau P, Martin J B
Brain Res. 1977 May 20;127(1):137-52. doi: 10.1016/0006-8993(77)90385-7.
Fifteen minute sequential blood sampling of male rats via right atrial cannulae was used to examine the patterns of anterior pituitary hormone secretion following hypothalamic deafferentations. Growth hormone (rGH) profiles from rats with complete hypothalamic deafferentation (CC) showed persistence of episodic rGH secretion with greatly increased frequency and elevated trough values, but without apparent entrainment to the light-dark cycle. Anterior (AC) and posterior (PC) deafferentation had no effect on the normal 3 h periodicity of rGH secretory episodes, but light-dark entrainment was lost in AC rats. Prolactin (rPRL) secretion in CC rats remained at normal low baseline levels without secretory episodes, while in AC and PC rats, as in normal rats, bursts of rPRL secretion occurred, often temporally related to rGH bursts. Thyrotropin (rTSH) levels in CC rats were less variable, and lower than in normal rats, while rTSH secretory profiles appeared normal in AC and PC rats. These results suggest that the isolated medial basal hypothalamus (MBH) contains neural substrates for episodic rGH secretion, and to a lesser extent, for rTSH. It is hypothesized that excessive rGH secretion in CC rats results from surgery damaging the rhythmicity of the rGH releasing factor (GRF) michanism, so that both sustained secretion and more frequent bursts of GRF occur. An effective rPRL inhibitory mechanism remains intact within complete hypothalamic deafferentations, while episodic rPRL and rTSH secretion require intact lateral afferents to the MBH. Visual pathway connections to the MBH, which mediate light-dark cycle entrainment of episodic rGH secretion, appear to pass through the region of the anterior hypothalamic and suprachiasmatic nuclei.
通过右心房插管对雄性大鼠进行15分钟的连续采血，以研究下丘脑去传入神经后垂体前叶激素的分泌模式。完全下丘脑去传入神经（CC）大鼠的生长激素（rGH）谱显示，rGH分泌呈间歇性，频率大幅增加，谷值升高，但未明显受明暗周期影响。前侧（AC）和后侧（PC）去传入神经对rGH分泌发作的正常3小时周期性没有影响，但AC大鼠失去了明暗周期同步性。CC大鼠的催乳素（rPRL）分泌保持在正常低基线水平，无分泌发作，而在AC和PC大鼠中，与正常大鼠一样，会出现rPRL分泌高峰，且通常与rGH高峰在时间上相关。CC大鼠的促甲状腺激素（rTSH）水平变化较小，且低于正常大鼠，而AC和PC大鼠的rTSH分泌谱似乎正常。这些结果表明，孤立的内侧基底下丘脑（MBH）含有间歇性rGH分泌的神经基质，在较小程度上也含有rTSH分泌的神经基质。据推测，CC大鼠中rGH分泌过多是由于手术破坏了rGH释放因子（GRF）机制的节律性，从而导致GRF持续分泌和更频繁的释放。在完全下丘脑去传入神经的情况下，有效的rPRL抑制机制仍然完整，而间歇性rPRL和rTSH分泌需要MBH外侧传入神经完整。介导间歇性rGH分泌的明暗周期同步的视通路与MBH的连接似乎穿过下丘脑前部和视交叉上核区域。
