Alexander M J, Leeman S E
Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Massachusetts 02118.
J Comp Neurol. 1994 Jul 22;345(4):496-509. doi: 10.1002/cne.903450403.
Neurotensin (NT) neurons in the rat preoptic area are implicated in female-specific regulation of reproduction. Estrogen markedly increases expression of mRNA encoding the neurotensin/neuromedin N (NT/N) precursor in several cell groups of the preoptic area, including the anteroventral periventricular nucleus, periventricular preoptic nucleus, and medial preoptic nucleus. In the present study, immunohistochemistry was performed on tissue from ovariectomized females with or without estradiol treatment to test the hypothesis that increased levels of NT accompany hormonal induction of NT/N mRNA in these cell group. Since colchicine treatment is required for visualization of NT-immunoreactive cell bodies, an additional objective of this study was to determine whether colchicine alters expression of NT/N mRNA in this area. Estradiol caused a pronounced increase in the number of NT-immunoreactive cell bodies in the anteroventral periventricular nucleus, as well as adjacent parts of the periventricular preoptic nucleus and medial preoptic nucleus. In the absence of colchicine, estradiol increased the number of NT-immunoreactive fibers in these same regions. Surprisingly, NT-immunoreactive cell bodies with intense staining were abundant in certain parts of the medial preoptic nucleus regardless of hormonal condition. NT-immunoreactive cell bodies were also numerous in certain regions where NT/N mRNA-expressing cells are scarce, and in two of these regions, the median preoptic nucleus and vascular organ of the lamina terminalis, estradiol substantially reduced the number of immunoreactive cell bodies. Treatment of ovariectomized females with colchicine induced expression of NT/N mRNA in the same regions where NT-immunoreactive cell bodies were unexpectedly numerous, thus providing a compelling explanation for the discordant distributions of the mRNA and peptide. Together with previous findings, the present results indicate that increased levels of NT accompany hormonal induction of NT/N mRNA in the anteroventral periventricular nucleus, as well as adjacent parts of the periventricular preoptic nucleus and medial preoptic nucleus. In other regions of the preoptic area, colchicine-inducible expression of NT/N mRNA confounds assessment of hormonal influences on NT synthesis. Multiple populations of neurons capable of NT synthesis can be distinguished in the rostral preoptic area on the basis of differential responsiveness to estrogen or colchicine, thereby providing additional evidence for functional heterogeneity among NT-synthesizing neurons in this region.
大鼠视前区的神经降压素（NT）神经元与雌性特异性生殖调节有关。雌激素显著增加视前区几个细胞群中编码神经降压素/神经介素N（NT/N）前体的mRNA表达，这些细胞群包括室周前腹核、室周视前核和内侧视前核。在本研究中，对接受或未接受雌二醇治疗的去卵巢雌性大鼠的组织进行免疫组织化学，以检验在这些细胞群中NT水平升高与NT/N mRNA的激素诱导相伴的假说。由于需要秋水仙碱处理才能使NT免疫反应性细胞体可视化，本研究的另一个目的是确定秋水仙碱是否会改变该区域NT/N mRNA的表达。雌二醇使室周前腹核以及室周视前核和内侧视前核相邻部分中NT免疫反应性细胞体的数量显著增加。在没有秋水仙碱的情况下，雌二醇增加了这些相同区域中NT免疫反应性纤维的数量。令人惊讶的是，无论激素状态如何，内侧视前核的某些部分都有大量染色强烈的NT免疫反应性细胞体。在某些NT/N mRNA表达细胞稀少的区域也有大量NT免疫反应性细胞体，在其中两个区域，即视前正中核和终板血管器，雌二醇显著减少了免疫反应性细胞体的数量。用秋水仙碱处理去卵巢雌性大鼠会在NT免疫反应性细胞体数量意外众多的相同区域诱导NT/N mRNA的表达，从而为mRNA和肽的不一致分布提供了令人信服的解释。与先前的研究结果一起，目前的结果表明，在室周前腹核以及室周视前核和内侧视前核相邻部分，NT水平升高与NT/N mRNA的激素诱导相伴。在视前区的其他区域，秋水仙碱诱导的NT/N mRNA表达混淆了对激素对NT合成影响的评估。根据对雌激素或秋水仙碱的不同反应性，可以在吻侧视前区分辨出多个能够合成NT的神经元群体，从而为该区域NT合成神经元之间的功能异质性提供了额外证据。
