Fenelon V S, Poulain D A, Theodosis D T
Laboratoire de Neuroendocrinologie Morphofonctionelle, INSERM CJF 91.10, Université de Bordeaux II, France.
Neuroscience. 1993 Mar;53(1):77-89. doi: 10.1016/0306-4522(93)90286-o.
As c-fos expression is generally thought to be linked to neuronal activation, we compared Fos immunoreactivity in identified oxytocinergic and vasopressinergic neurons of female rats under various conditions known to elicit particular patterns of electrophysiological and secretory activity in these neurons. In suckled lactating animals, Fos immunoreactivity was visible only in rare oxytocinergic and vasopressinergic neurons of the paraventricular and supraoptic nuclei, even after interruption of suckling for 18-72 h. On the other hand, many Fos-positive cells were visible in the nuclei of parturient rats; they involved about 25% of supraoptic oxytocinergic elements. Even more Fos-positive elements were visible in the nuclei of lactating rats that had also undergone 24 h water deprivation or haemorrhage. This involved about 75% vasopressinergic neurons and 25% oxytocinergic neurons of the supraoptic nucleus. Fos immunoreactivity was particularly conspicuous in oxytocin neurons of the anterior commissural nucleus after haemorrhage. After water deprivation or haemorrhage, Fos-positive oxytocinergic neurons in the supraoptic nucleus were significantly more numerous in virgin rats than in lactating rats. Our observations show that suckling, although a most potent stimulus for oxytocin neuron activation and oxytocin release, is inefficient in inducing Fos synthesis in magnocellular neurons, even after a period of interruption. On the other hand, parturition, water deprivation and haemorrhage were more potent stimuli for both neurosecretory systems. However, under each type of stimulation, only part of the neuronal populations within each nucleus were Fos-positive, suggesting that different stimulus-specific pathways are involved in these regulations. In so far as electrical activity is one possible mechanism for c-fos expression, comparison of the patterns of c-fos activation with the known electrophysiological behaviour of hypothalamic magnocellular neurons suggests that Fos synthesis in these neurons is linked to the number of action potentials generated over a period of time, more than to the pattern of electrical activity, whatever the physiological impact of this pattern. Furthermore, within a group of neurons, the heterogeneity of the response in terms of Fos synthesis may be correlated to the variability of the electrophysiological response within this group.
由于一般认为c-fos表达与神经元激活有关，我们比较了在已知能引发这些神经元特定电生理和分泌活动模式的各种条件下，雌性大鼠中已确定的催产素能和加压素能神经元的Fos免疫反应性。在哺乳的泌乳动物中，即使在停止哺乳18 - 72小时后，Fos免疫反应性也仅在室旁核和视上核中罕见的催产素能和加压素能神经元中可见。另一方面，在分娩大鼠的核中可见许多Fos阳性细胞；它们约占视上核催产素能成分的25%。在也经历了24小时缺水或出血的泌乳大鼠的核中，可见更多的Fos阳性成分。这涉及视上核中约75%的加压素能神经元和25%的催产素能神经元。出血后，前连合核的催产素神经元中的Fos免疫反应性尤为明显。缺水或出血后，视上核中Fos阳性的催产素能神经元在未生育大鼠中比在泌乳大鼠中明显更多。我们的观察表明，哺乳虽然是催产素神经元激活和催产素释放的最有效刺激，但即使在一段时间的中断后，在诱导大细胞神经元中Fos合成方面效率也不高。另一方面，分娩、缺水和出血对这两个神经分泌系统都是更强的刺激。然而，在每种刺激类型下，每个核内只有部分神经元群体是Fos阳性的，这表明不同的刺激特异性途径参与了这些调节。就电活动是c-fos表达的一种可能机制而言，将c-fos激活模式与下丘脑大细胞神经元已知的电生理行为进行比较表明，这些神经元中的Fos合成与一段时间内产生的动作电位数量有关，而不仅仅与电活动模式有关，无论这种模式的生理影响如何。此外，在一组神经元中，Fos合成反应的异质性可能与该组内电生理反应的变异性相关。
