Department of Neuroscience, Karolinska Institutet, Stockholm, 17177, Sweden
Department of Neuroscience, Karolinska Institutet, Stockholm, 17177, Sweden.
J Neurosci. 2020 Apr 15;40(16):3203-3216. doi: 10.1523/JNEUROSCI.1553-18.2020. Epub 2020 Mar 24.
Giving birth triggers a wide repertoire of physiological and behavioral changes in the mother to enable her to feed and care for her offspring. These changes require coordination and are often orchestrated from the CNS, through as of yet poorly understood mechanisms. A neuronal population with a central role in puerperal changes is the tuberoinfundibular dopamine (TIDA) neurons that control release of the pituitary hormone, prolactin, which triggers key maternal adaptations, including lactation and maternal care. Here, we used Ca imaging on mice from both sexes and whole-cell recordings on female mouse TIDA neurons to examine whether they adapt their cellular and network activity according to reproductive state. In the high-prolactin state of lactation, TIDA neurons shift to faster membrane potential oscillations, a reconfiguration that reverses upon weaning. During the estrous cycle, however, which includes a brief, but pronounced, prolactin peak, oscillation frequency remains stable. An increase in the hyperpolarization-activated mixed cation current, I, possibly through unmasking as dopamine release drops during nursing, may partially explain the reconfiguration of TIDA rhythms. These findings identify a reversible plasticity in hypothalamic network activity that can serve to adapt the dam for motherhood. Motherhood requires profound behavioral and physiological adaptations to enable caring for offspring, but the underlying CNS changes are poorly understood. Here, we show that, during lactation, neuroendocrine dopamine neurons, the "TIDA" cells that control prolactin secretion, reorganize their trademark oscillations to discharge in faster frequencies. Unlike previous studies, which typically have focused on structural and transcriptional changes during pregnancy and lactation, we demonstrate a functional switch in activity and one that, distinct from previously described puerperal modifications, reverses fully on weaning. We further provide evidence that a specific conductance (I) contributes to the altered network rhythm. These findings identify a new facet of maternal brain plasticity at the level of membrane properties and consequent ensemble activity.
分娩会引发母亲广泛的生理和行为变化，使她能够喂养和照顾后代。这些变化需要协调，通常是由中枢神经系统通过目前尚不清楚的机制来协调的。在产后期变化中起核心作用的神经元群体是调节垂体激素催乳素释放的结节漏斗多巴胺（TIDA）神经元，催乳素触发关键的母体适应，包括泌乳和母性照顾。在这里，我们使用来自雌雄小鼠的钙成像和雌性小鼠 TIDA 神经元的全细胞记录来检查它们是否根据生殖状态来适应其细胞和网络活动。在哺乳期高催乳素状态下，TIDA 神经元向更快的膜电位振荡转变，这种重构在断奶后逆转。然而，在发情周期中，包括短暂但明显的催乳素高峰，振荡频率保持稳定。超极化激活混合阳离子电流 I 的增加，可能是由于在哺乳期间多巴胺释放减少而被揭示出来，可能部分解释了 TIDA 节律的重构。这些发现确定了下丘脑网络活动的可逆可塑性，可用于使母鼠适应母性。母性需要深刻的行为和生理适应来照顾后代，但中枢神经系统的变化知之甚少。在这里，我们表明，在哺乳期，神经内分泌多巴胺神经元，即控制催乳素分泌的“TIDA”细胞，重新组织其标志性的振荡以更快的频率放电。与之前通常集中在怀孕和哺乳期结构和转录变化的研究不同，我们证明了活动中的功能切换，并且与之前描述的产后期修饰不同，完全在断奶后逆转。我们进一步提供证据表明，特定的电导率（I）有助于改变网络节律。这些发现确定了母体大脑可塑性在膜特性和随之而来的整体活动水平上的一个新方面。
