VENTROMEDIAL HYPOTHALAMUS AS A TARGET FOR ESTRADIOL ACTION ON PROCEPTIVITY, RECEPTIVITY AND LUTEINIZING-HORMONE SURGE OF THE EWE
VENTROMEDIAL HYPOTHALAMUS AS A TARGET FOR ESTRADIOL ACTION ON PROCEPTIVITY, RECEPTIVITY AND LUTEINIZING-HORMONE SURGE OF THE EWE
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DOI：
10.1016/0006-8993(91)91488-m
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发表时间：
1991-04-19
期刊：
影响因子：
2.9
通讯作者：
VENIER, G
中科院分区：
文献类型：
--
作者：
BLACHE, D;FABRENYS, CJ;VENIER, G
大多数文献表明，羊和啮齿类动物一样，与雌性性行为有关的神经结构与与LH激增有关的神经结构不一定相同。在啮齿类动物中，雌二醇通过作用于中基底下丘脑的一个有限区域来触发雌性性行为，而伴随而来的促排卵前LH激增至少部分受到更前部结构的控制。然而，雌二醇作用的中心部位在绵羊中仍不明确。为了提供这一定义，37只卵巢切除的母羊在视前区（POA）、前、中基底、外侧或后下丘脑（AH、MBH、LHT、PH）立体定向植入引导套管。实验是在繁殖季节（Br）和发情期（An: unilat）进行的，雌性小鼠接受孕酮和17- β -雌二醇（低于阈值）的外周治疗，对LH激增和性行为都有影响。在去除黄体酮16小时后，将0.45 mm的结晶E2植入颅骨（i.d = 0.45 mm）降低，并将其留在脑内48小时。然而POA植入物对行为或LH激增没有任何显著影响，所有MBH植入物都引起了接受性（11 bilat， 5 unilat Br和5 unilat An）。双侧MBH植入还诱导了11只母羊中的9只母羊的敏感性，并增加了其中7只母羊的LH水平。这些比例与外周注射25 μ g E2后观察到的没有显著差异。单侧MBH植入物对感受性和LH增加无显著影响，但一些植入物放置在MBH外侧（2/5受体和3/5受体）可诱导动情行为。脑植入后的发情行为质量与外周类固醇治疗后观察到的发情行为质量没有显著差异，这表明所有需要完全表达发情的大脑区域都受到了刺激。然而，植入后的LH升高幅度低于注射类固醇后的LH升高幅度；我们认为这是由于对脑垂体的刺激不足。这些结果表明，母羊的下丘脑中基底区是雌二醇触发性行为和黄体生成素激增的重要部位。
Most of the literature suggests that in sheep as in rodents nervous structures involved in female sexual behaviour are not necessarily identical to those involved in the LH surge. In rodents, oestradiol triggers female sexual behaviour by acting on a restricted area of the mediobasal hypothalamus whereas the concomitant induction of the preovulatory LH surge is at least partially under the control of more anterior structures. The central sites of oestradiol action, however, remained poorly defined in sheep. To provide this definition, 37 ovariectomized ewes were stereotaxically implanted unilaterally or bilaterally with a guide cannula in preoptic area (POA), anterior, mediobasal, lateral, or posterior hypothalamus (AH, MBH, LHT, PH). Experiments were made during the breeding season (Br) and the anoestrous period (An: unilat only) and females were primed with a peripheral treatment of progesterone and a dose of 17-beta-oestradiol subthreshold for both the LH surge and sexual behaviour. Intracranial implants (i.d. = 0.45 mm) of crystalline E2 were lowered 16 h after progesterone removal and left in the brain for 48 h. Whereas POA implants never had any significant effects on either the behaviour or the LH surge, all MBH implants caused receptivity (11 bilat, 5 unilat Br and 5 unilat An). Bilateral MBH implants also induced proceptivity in 9 of 11 ewes and increased the LH levels in 7 of them. These proportions do not differ significantly from those observed after a 25-mu-g peripheral injection of E2. Unilateral MBH implants had no significant effect on proceptivity and LH increase but oestrous behaviour was induced by some implants placed laterally to the MBH (2/5 recept and 3/5 procept). The quality of oestrous behaviour after brain implants was not significantly different from that observed after peripheral steroid treatment, showing that all brain areas needed for full expression of oestrus have been stimulated. The amplitude of the LH increase, however, was lower after implantation than after i.m. injection of the steroid; we propose that this is due to an insufficient stimulation of the hypophysis. These results show that in the ewe, a restricted are in the mediobasal hypothalamus is an important site of oestradiol action to trigger both sexual behaviour and the LH surge.