ESTROGEN-REGULATED SYNTHESIS OF NEUROTENSIN IN NEUROSECRETORY-CELLS OF THE HYPOTHALAMIC ARCUATE NUCLEUS IN THE FEMALE RAT
ESTROGEN-REGULATED SYNTHESIS OF NEUROTENSIN IN NEUROSECRETORY-CELLS OF THE HYPOTHALAMIC ARCUATE NUCLEUS IN THE FEMALE RAT
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DOI：
10.1210/en.133.4.1809
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发表时间：
1993-10-01
期刊：
影响因子：
4.8
通讯作者：
ALEXANDER, MJ
中科院分区：
文献类型：
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作者：
ALEXANDER, MJ
神经降压素（NT）在哺乳动物中被认为是一种神经激素，但该肽的神经内分泌作用仍有待确定。NT免疫反应已观察到弓状核和室旁核的神经分泌细胞，数据表明，NT释放到垂体门静脉血介导的PRL分泌的一个组成部分，是女性特异性和依赖于卵巢类固醇。本研究采用原位杂交组织化学和免疫组织化学方法研究成年大鼠下丘脑神经分泌区NT基因表达的调节。在卵巢切除的女性，雌二醇诱导表达的信使RNA（mRNA）编码NT和神经介肽N（NT/N mRNA）的背内侧部的弓状核。与此相反，雌二醇并没有明显改变NT/N mRNA表达的腹外侧部的弓状核，其中标记的细胞是众多的，或在室旁核，标记的细胞几乎不存在。雌激素还增加了NT免疫反应的外部区域的正中隆起，确认神经内分泌表型的NT细胞的背内侧分裂，以及雌激素调节合成的NT在这个系统中。在骑自行车的女性，NT/N mRNA表达细胞的背内侧分裂显着更多的发情前期比间情期，在这些阶段的血浆雌二醇水平的差异一致。在同一区域，NT/N mRNA表达细胞显着更多的发情前期女性比性腺完整的男性。这些结果表明，雌激素调节的NT释放在正中隆起subserves一个或多个性分化的功能，并与tuberoinfundibular NT参与雌激素依赖性分泌的PRL或GnRH的下午的发情前期。
Neurotensin (NT) is implicated as a neurohormone in mammals, yet the peptide's neuroendocrine role remains to be determined. NT immunoreactivity has been observed in neurosecretory cells of the arcuate nucleus and paraventricular nucleus, and data suggest that NT release into hypophysial portal blood mediates a component of PRL secretion that is female specific and dependent on ovarian steroids. In the present study, in situ hybridization histochemistry and immunohistochemistry were used to investigate the regulation of NT gene expression in hypothalamic neurosecretory regions of adult rats. In ovariectomized females, estradiol induced expression of messenger RNA (mRNA) encoding NT and neuromedin N (NT/N mRNA) in the dorsomedial division of the arcuate nucleus. In contrast, estradiol did not appreciably alter NT/N mRNA expression in the ventrolateral division of the arcuate nucleus, where labeled cells were numerous, or in the paraventricular nucleus, where labeled cells were virtually absent. Estradiol also increased NT immunoreactivity in the external zone of the median eminence, confirming the neuroendocrine phenotype of NT cells in the dorsomedial division, as well as estrogen-regulated synthesis of NT in this system. In the dorsomedial division of cycling females, NT/N mRNA-expressing cells were significantly more numerous at proestrus than at diestrus, consistent with differences in plasma estradiol levels at these stages. In this same region, NT/N mRNA-expressing cells were significantly more numerous in proestrous females than in gonad-intact males. These results imply that estrogen-regulated release of NT at the median eminence subserves one or more sexually differentiated functions and are consistent with the involvement of tuberoinfundibular NT in estrogen-dependent secretion of PRL or GnRH on the afternoon of proestrus.