Lonstein J S, Simmons D A, Swann J M, Stern J M
Department of Psychology, Rutgers University, New Brunswick, NJ 08903, USA.
Neuroscience. 1998 Jan;82(1):267-81. doi: 10.1016/s0306-4522(97)00283-2.
To reveal brain sites simultaneously active during the expression of maternal behaviour in lactating rats, we used immunocytochemical visualization of the nuclear protein product Fos of the immediate-early gene c-fos as a marker of neuronal activity. After a 48 h separation from their litter, day 7 postpartum dams received a 1 h period of physical interaction with pups either capable or incapable of suckling, inaccessible pups in a wire-mesh box, an empty box, or no stimulation. Physical interaction with pups elicited high levels of pronurturant maternal behaviour (retrieval, licking, mouthing), and suckling elicited nursing behaviour as well. Exposure to the box, with or without pups, elicited high levels of investigatory sniffing, self-grooming, and general activity. Distal stimulation from pups did not differentially activate Fos in any of 20 sites, including olfactory-processing structures such as the piriform cortex and medial amygdala. Physical interaction with pups, with or without suckling, elicited higher levels of Fos-immunoreactive nuclei than that of other conditions in numerous sites, including many previously implicated in maternal behaviour (medial preoptic nucleus, nucleus accumbens, lateral septum, lateral habenula, and the bed nucleus of the stria terminalis). Similar group patterns of Fos expression also occurred in sites not previously implicated in maternal behaviour (somatosensory cortex and paraventricular thalamic nucleus). Interaction with nonsuckling pups elicited the highest levels of Fos in the cortical amygdala, whereas suckling did not activate higher Fos than nonsuckling interaction in any site included in this report, including hypothalamic nuclei involved in lactation (paraventricular, supraoptic, and arcuate). There was little or no Fos in cingulate cortex, olfactory tubercle, medial septum, medial habenula, or ventromedial hypothalamus. These data suggest that trigeminal stimuli received by lactating rats during the performance of pronurturant maternal behaviour promote cellular activity resulting in neuronal expression of c-fos in many forebrain sites including the medial preoptic nucleus, several sites connected with it that are part of the mesotelencephalic dopamine system, and in the somatosensory cortex. In contrast, in these forebrain sites suckling does not elicit greater levels of Fos than that seen in nonsuckled rats and distal stimuli from pups are ineffective in increasing Fos levels compared with non-stimulated controls.
为了揭示泌乳期大鼠表现母性行为时同时活跃的脑区，我们使用免疫细胞化学方法可视化即刻早期基因c-fos的核蛋白产物Fos，将其作为神经元活动的标志物。在与幼崽分离48小时后，产后第7天的母鼠与能够或不能哺乳的幼崽进行1小时的身体互动，或者在金属丝网箱中接触无法触及的幼崽、空箱子，或者不给予刺激。与幼崽的身体互动引发了高水平的促养育母性行为（找回、舔舐、口含），哺乳也引发了哺育行为。接触装有或未装幼崽的箱子引发了高水平的探究性嗅闻、自我梳理和一般活动。来自幼崽的远距离刺激在包括梨状皮层和内侧杏仁核等嗅觉处理结构在内的20个脑区中均未差异激活Fos。与幼崽的身体互动，无论有无哺乳，在许多脑区引发的Fos免疫反应性细胞核水平均高于其他条件下，这些脑区包括许多先前与母性行为有关的脑区（内侧视前核、伏隔核、外侧隔核、外侧缰核和终纹床核）。Fos表达的类似组模式也出现在先前未与母性行为有关的脑区（躯体感觉皮层和丘脑室旁核）。与不能哺乳的幼崽互动在皮质杏仁核中引发了最高水平的Fos，而在本报告所包括的任何脑区，包括参与泌乳的下丘脑核（室旁核、视上核和弓状核）中，哺乳引发的Fos水平均不高于与不能哺乳的幼崽互动。扣带回皮层、嗅结节、内侧隔核、内侧缰核或下丘脑腹内侧核中几乎没有或没有Fos。这些数据表明，泌乳期大鼠在表现促养育母性行为时接收到的三叉神经刺激促进了细胞活动，导致包括内侧视前核、与之相连的作为中脑边缘多巴胺系统一部分的几个脑区以及躯体感觉皮层在内的许多前脑脑区中c-fos的神经元表达。相比之下，在这些前脑脑区中，哺乳引发的Fos水平并不高于未哺乳大鼠，并且与未受刺激的对照组相比，来自幼崽的远距离刺激在增加Fos水平方面无效。
