Effect of constant light and androgen-sterilization on the amine turnover of the tubero-infundibular dopamine neurons: blockade of cyclic activity and induction of a persistent high dopamine turnover in the median eminence.
Effect of constant light and androgen-sterilization on the amine turnover of the tubero-infundibular dopamine neurons: blockade of cyclic activity and induction of a persistent high dopamine turnover in the median eminence.
复制标题
恒定光和雄激素灭菌对结节漏斗多巴胺神经元胺周转的影响：阻断循环活动并诱导正中隆起持续高多巴胺周转。
DOI：
10.1530/acta.0.0690625
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发表时间：
1972
期刊：
影响因子：
--
通讯作者：
O. Nilsson
中科院分区：
文献类型：
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作者：
K. Fuxe;T. Hökfelt;O. Nilsson
研究了正常卵巢周期、恒定光照下大鼠和雄激素不育大鼠经酪氨酸羟化酶抑制剂\g=a\-甲基酪氨酸-甲基lester处理后正中突起和新纹状体的多巴胺（DA）周转情况。DA的消耗率提供了对周转量的估计，这可以通过Falck和Hillarp的高度敏感和特异性的组织化学荧光方法进行半定量评估，以证明儿茶酚胺（CA）的存在。结果显示卵巢周期中结节-漏斗DA神经元的循环转换发生变化，而新纹状体DA神经元的循环转换不发生变化。发情期前和发情期早期营业额减少。在持续发情的大鼠中，无论是持续光照还是新生儿类固醇治疗，均未发生中隆起DA转换的周期性变化。这些大鼠的周转率保持在恒定的高水平，与正常循环大鼠的雌情期相似。在持续发情的大鼠中，高雌激素分泌可能是高DA转换的原因，因为在这些大鼠中，去势导致了显著的DA转换。这篇论文在1968年5月在波士顿举行的NPR“单胺和神经内分泌学”工作会议和1968年7月在墨西哥城举行的第三届国际内分泌学会议上部分发表。从Bioscientifica.com下载于11/27/2018 12:49:54PM通过免费访问减少DA营业额。睾酮和雌激素引起雄激素绝育的阉割大鼠中隆起DA周转率的剂量依赖性增加。与正常去势大鼠相比，雄激素绝育大鼠的DA神经元对雌激素的敏感性有所降低。本研究结果支持如下观点：结节-漏斗DA神经元参与抑制正中隆起LHRF和FSHRF的循环释放，雌激素和睾酮的抑制反馈作用部分是通过增加正中隆起DA的周转和释放，从而抑制LHRF和FSHRF的释放。Fuxe et al. 1967、19696等文献报道，在妊娠、哺乳期和假妊娠期间，即FSH和LH分泌较低和排卵被阻断的情况下，结节-基底DA神经元的活性显著增加。此外，有简要报道（Fuxe et al. 1967），在发情周期中，结节-漏斗DA神经元的活动发生周期性变化，在发情前期和发情早期活动较低，这表明在LHRF释放时，该系统的活动较低。随后，一项详细的研究显示，在关键时期之前，早在发情前期，正中隆起的DA活性就已经下降。同一组大鼠在发情前下午释放黄体生成素与垂体黄体生成素含量下降（ahr<s:1>等人，1971）。这些结果提示，垂体后叶DA神经元可能参与控制垂体前叶促性腺激素的分泌。鉴于所观察到的转换变化，假设中隆起的DA神经元部分通过抑制中隆起的LHRF分泌而起作用。为了研究这一假说，还研究了其他与排卵受阻有关的情况，即由持续光照或雄激素绝育引起的持续发情综合征。此外，在雄激素绝育的大鼠中进行了阉割和性激素治疗。材料与方法
The dopamine (DA) turnover in the median eminence and in the neostriatum in the rat has been studied during the normal ovarian cycle, in rats exposed to constant light and in androgen-sterilized rats treated with the tyrosine hydroxylase inhibitor \g=a\-methyl-tyrosine-methylester. The rate of depletion of DA provides an estimation of the turnover and this can be evaluated semi-quantitatively by means of the highly sensitive and specific histochemical fluorescence method of Falck and Hillarp for the demonstration of catecholamines (CA). The results reveal cyclic turnover changes in the tubero-infundibular DA neurons during the ovarian cycle but not in the neostriatal DA neurons. The turnover is decreased during pro-oestrus and early oestrus. In the persistent oestrous rats, whether induced by constant light or by neonatal steroid treatment, no cyclic changes in DA turnover in the median eminence occurred. The turnover remained at a constant high level in these rats, similar to that found in dioestrus of normal cycling rats. The high oestrogen secretion in persistent oestrous rats was probably responsible for the high DA turnover, since in these rats castration caused a marked This paper was presented in part at the NPR Work Session on »Monoamines and Neuroendocrinology«, May 1968, in Boston, and at the Third International Endo¬ crinology Meeting, July 1968, in Mexico City. Downloaded from Bioscientifica.com at 11/27/2018 12:49:54PM via free access reduction in the DA turnover. Testosterone and oestrogen caused a dosedependent increase in DA turnover in the median eminence in androgensterilized castrated rats. The DA neurons of the androgen-sterilized castrated rats were found to be somewhat less sensitive to treatment with oestrogen than those of normal castrated rats. The present results support the view that the tubero-infundibular DA neurons participate in the inhibition of the cyclic release of LHRF and FSHRF from the median eminence and that the inhibitory feed-back action of oestrogen and testosterone is partly mediated via an increase in DA turnover and release in the median eminence, resulting in inhibition of LHRF and-FSHRF release. In previous papers (Fuxe et al. 1967, 19696) it has been reported that the activity of the tubero-infundibular DA neurons is markedly increased during pregnancy, lactation and pseudo-pregnancy, i.e. conditions in which there is a low FSH and LH secretion and blockade of ovulation. Furthermore, it has been briefly reported (Fuxe et al. 1967) that the tubero-infundibular DA neurons undergo cyclic activity changes during the oestrous cycle with low activity during pro-oestrus and early oestrus, suggesting that at the time of LHRF release the activity of the system is low. Subsequently, a detailed study revealed a decrease in DA activity in the median eminence already in early pro-oestrus before the critical period. The release of LH in the afternoon of pro-oestrus was indicated in the same group of rats as a fall in pituitary LH content (Ahrén et al. 1971). All these findings suggest that the tubero-infundibular DA neurons may be involved in the control of gonadotrophin secretion from the anterior pituitary. In view of the turnover changes observed it was postulated that the DA neurons in the median eminence act partly by inhibiting LHRF secretion from the median eminence. In order to study this hypothesis, other conditions involving blockade of ovulation have been studied, i. e. the persistent oestrous syndrome induced by constant light or by androgen-sterilization. Furthermore, castration and treatment with sex hormones have been performed in androgen-sterilized rats. MATERIAL AND METHODS