T3 implantation mimics photoperiodically reduced encasement of nerve terminals by glial processes in the median eminence of Japanese quail
T3 implantation mimics photoperiodically reduced encasement of nerve terminals by glial processes in the median eminence of Japanese quail
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DOI：
10.1007/s00441-005-0126-8
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发表时间：
2006-04-01
影响因子：
3.6
通讯作者：
Yoshimura, T
中科院分区：
文献类型：
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作者：
Yamamura, T;Yasuo, S;Yoshimura, T
下丘脑内侧基底区的光周期产生的三碘甲状腺原氨酸(T-3)在日本鹌鹑性腺的光周期反应中起关键作用。在以前的研究中，我们展示了促性腺激素释放激素(GnRH)神经末梢和正中隆起(ME)神经胶质终末之间神经胶质相互作用的季节性形态变化。然而，光周期产生的T-3和ME的季节性神经胶质可塑性之间的直接关系仍然不清楚。在本研究中，我们观察了T-3注入MBH对ME内神经-神经胶质细胞相互作用的影响。T-3植入可引起睾丸生长，减少ME外区神经末梢的包绕。相比之下，给予过量T-3的鸟类没有观察到形态变化，T-3不会导致睾丸生长。这些结果支持甲状腺激素通过ME的神经胶质可塑性来调节光周期GnRH分泌的假说。
Photoperiodically generated triiodothyronin (T-3) in the mediobasal hypothalamus (MBH) has critical roles in the photoperiodic response of the gonads in Japanese quail. In a previous study, we demonstrated seasonal morphological changes in the neuro-glial interaction between gonadotrophin-releasing hormone (GnRH) nerve terminals and glial endfeet in the median eminence (ME). However, a direct relationship between photoperiodically generated T-3 and seasonal neuro-glial plasticity in the ME remained unclear. In the present study, we examined the effect of T-3 implantation into the MBH on the neuro-glial interaction in the ME. T-3 implantation caused testicular growth and reduced encasement of nerve terminals in the external zone of the ME. In contrast, no morphological changes were observed in birds given an excessive dose of T-3, which did not cause testicular growth. These results support the hypothesis that thyroid hormone regulates photoperiodic GnRH secretion via neuro-glial plasticity in the ME.