Bale T L, Dorsa D M, Johnston C A
Department of Pharmacology, University of Washington, Seattle 98195, USA.
J Neurosci. 1995 Jul;15(7 Pt 1):5058-64. doi: 10.1523/JNEUROSCI.15-07-05058.1995.
Changes in OR mRNA expression in the ventromedial hypothalamus (VMH) in relation to the estrous cycle were measured by in situ hybridization with a rat oxytocin receptor (OR) probe. Binding studies have localized ORs to various brain regions, and have detected a high density of receptors in the VMH, a nucleus containing large numbers of estrogen responsive neurons. Previous studies in this lab have reported a significant increase in OR mRNA expression in the VMH in ovariectomized rats treated with estrogen. The present study was designed to determine whether changes in steroid hormone levels across the estrous cycle result in induction of OR mRNA expression. Autoradiographic studies revealed differences in OR mRNA expression in the rostral and caudal as well as medial and lateral aspects of the VMH. OR mRNA levels were highest in the caudal portion of the vIVMH on the afternoon (16:00 hr) of proestrus. The rostral region exhibited a high level of expression in the ventrolateral region of the VMH on the morning (9:00 hr) of proestrus and in the dorsomedial region of the VMH on the afternoon of proestrus. Little or no OR mRNA expression was evident in the rostral or caudal VMH on the morning or evening of diestrus. These results support previous findings which showed a regulation of OR binding by gonadal steroids and suggest that this may be due to altered expression of the OR gene. These effects suggest a possible role of ORs in the oxytocin stimulated release of luteinizing hormone.
通过用大鼠催产素受体（OR）探针进行原位杂交，测量了与发情周期相关的腹内侧下丘脑（VMH）中OR mRNA表达的变化。结合研究已将OR定位到各个脑区，并在VMH中检测到高密度的受体，VMH是一个含有大量雌激素反应性神经元的核团。该实验室以前的研究报道，用雌激素处理的去卵巢大鼠VMH中OR mRNA表达显著增加。本研究旨在确定发情周期中类固醇激素水平的变化是否会导致OR mRNA表达的诱导。放射自显影研究揭示了VMH的头端和尾端以及内侧和外侧方面OR mRNA表达的差异。在发情前期下午（16:00时），VMH尾端部分的OR mRNA水平最高。在发情前期上午（9:00时），VMH腹外侧区域以及发情前期下午VMH背内侧区域的头端区域表现出高水平的表达。在动情后期的上午或晚上，头端或尾端VMH中几乎没有明显的OR mRNA表达。这些结果支持了先前的研究结果，即性腺类固醇对OR结合有调节作用，并表明这可能是由于OR基因表达的改变。这些效应表明OR在催产素刺激促黄体生成素释放中可能起作用。
