INSERM U176, University of Bordeaux II, 1 Rue Camille Saint-Saens, F-33077 Bordeaux Cedex, France.
J Neuroendocrinol. 1990 Apr 1;2(2):225-31. doi: 10.1111/j.1365-2826.1990.tb00855.x.
Abstract In earlier studies, we showed that continuous intracerebroventricular infusion of oxytocin, for several days, into the third ventricle of normally hydrated, non-lactating adult female rats significantly reduced glial coverage of magnocellular oxytocinergic neurons in the hypothalamus. It also induced synaptic remodelling whereby many oxytocinergic neurons became synaptically contacted by the same presynaptic terminals (shared synapses). Such changes were closely similar to those observed in the oxytocinergic system when it is physiologically activated, as during parturition and lactation. We now report that central oxytocin does not act alone to modify the ultrastructure of the magnocellular nuclei, but requires the concomitant action of sex steroids. Intracerebroventricular infusion of oxytocin was effective in inducing neuronal-glial and synaptic changes only in supraoptic nuclei of female rats undergoing a prolonged diestrus, or in castrated female rats treated during the infusion period with daily intramuscular injections of progesterone for 4 days followed by 17beta-estradiol for 2 days. Infusion of oxytocin in rats with regular estrous cycles, or in castrated rats treated with progesterone or estrogen alone had no effect on the ultrastructure of the nucleus. Our observations also indicate that the action of oxytocin on the anatomy of its own neurons is very specific: only 4-threonine-oxytocin, a closely related oxytocin analogue, had an effect similar to that of oxytocin; vasopressin, 4-threonine-7-glycine oxytocin and cholecystokinin left the magnocellular nuclei structurally unaltered.
摘要 在早期的研究中，我们发现连续数天向正常水合、非哺乳期成年雌性大鼠第三脑室中输注催产素会显著减少下丘脑大细胞催产素能神经元的神经胶质覆盖。它还诱导了突触重塑，使许多催产素能神经元被相同的突触前末端（共享突触）突触接触。这些变化与分娩和哺乳期期间催产素系统的生理性激活所观察到的变化非常相似。我们现在报告说，中枢催产素不会单独作用于改变大细胞核的超微结构，而是需要性激素的共同作用。只有在经历长时间动情间期的雌性大鼠或在输注期间每天接受肌内注射孕激素 4 天然后注射 17β-雌二醇 2 天的去势雌性大鼠的视上核中，向脑室内输注催产素才有效诱导神经元-神经胶质和突触变化。在具有正常动情周期的大鼠或单独用孕激素或雌激素处理的去势大鼠中，催产素的输注对核的超微结构没有影响。我们的观察还表明，催产素对其自身神经元解剖结构的作用非常特异：只有 4-苏氨酸-催产素，一种密切相关的催产素类似物，具有与催产素相似的作用；加压素、4-苏氨酸-7-甘氨酸催产素和胆囊收缩素使大细胞核的结构保持不变。
