Ventromedial hypothalamic mediation of photoperiodic gonadal responses in male syrian hamsters
Ventromedial hypothalamic mediation of photoperiodic gonadal responses in male syrian hamsters
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DOI：
10.1177/074873099129000795
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发表时间：
1999-10-01
影响因子：
3.5
通讯作者：
Zucker, I
中科院分区：
文献类型：
--
作者：
Bae, HH;Mangels, RA;Zucker, I
短日长诱导季节性繁殖的叙利亚仓鼠睾丸退化。为了测试睾丸消退后是否需要腹内侧下丘脑维持生殖静止，我们对光消退的雄性仓鼠进行了腹内侧下丘脑病变（VMHx）、松果体切除术（Pinx）或假手术（sham）。与Pinx和Sham仓鼠相比，VMHx仓鼠的性腺复发加速。与Sham仓鼠相比，VMHx组的催乳素浓度（PRL）恢复到长日仓鼠特征值的速度加快。VMHx和Pinx动物的卵泡刺激素（FSH）浓度在手术后几周开始过早升高。当性腺复发，仓鼠对褪黑激素产生抗性时，PRL和FSH浓度在所有组中都恢复到基线长时间值；在任何有病变的动物中，没有证据表明这两种激素分泌过多。VMH仓鼠的褪黑素浓度与假手术仓鼠的没有差异，但由于只进行了一次测定，因此VMH损伤仍有可能改变夜间褪黑素分泌的持续时间。完整的VMH似乎对于持续维持短日照引起的生殖抑制至关重要；这些和早期的研究结果表明，下丘脑下丘脑背内侧复合体在夏末和初秋白昼长度减少期间介导生殖器官的退化，也是维持冬季退化所必需的。
Short day lengths induce testicular regression in seasonally breeding Syrian hamsters. To test whether the ventromedial hypothalamus is necessary to maintain reproductive quiescence once testicular regression has been achieved, photoregressed male hamsters were subjected to lesions of the ventromedial hypothalamus (VMHx), pinealectomy (Pinx), or sham operation (Sham). VMHx hamsters underwent accelerated gonadal recrudescence compared to Pinx and Sham hamsters. Recovery of prolactin concentrations (PRL) to values characteristic of long-day hamsters was hastened in the VMHx animals compared to Sham hamsters. Concentrations of follicle stimulating hormone (FSH) increased prematurely in both the VMHx and Pinx animals, beginning a few weeks after surgery. By the time the gonads had undergone recrudescence and the hamsters were refractory to melatonin, PRL and FSH concentrations had returned to baseline long-day values in all groups; there was no evidence of hypersecretion of either hormone in any of the animals with lesions. Melatonin concentrations of VMHx hamsters did not differ from those of sham-operated animals, but because only a single determination was made, it remains possible that VMH damage altered the duration of nightly melatonin secretion. An intact VMH appears to be essential for the continued maintenance of reproductive suppression induced by exposure to short day lengths; these and earlier findings suggest that the VMH-dorsomedial hypothalamic complex mediates regression of the reproductive apparatus during decreasing day lengths of late summer and early autumn and also is necessary to sustain regression during the winter months.