Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
Neuron. 2010 Jan 28;65(2):217-29. doi: 10.1016/j.neuron.2009.12.024.
The pituitary hormone, prolactin, triggers lactation in nursing mothers. Under nonlactating conditions, prolactin secretion is suppressed by powerful inhibition from hypothalamic tuberoinfundibular dopamine (TIDA) neurons. Although firing pattern has been suggested as integral to neuroendocrine control, the electrical behavior of TIDA cells remains unknown. We demonstrate that rat TIDA neurons discharge rhythmically in a robust 0.05 Hz oscillation. The oscillation is phase locked between neurons, and while it persists during chemical synaptic transmission blockade, it is abolished by gap junction antagonists. Thyrotropin-releasing hormone (TRH) potently stimulates prolactin release, an effect assumed to take place in the pituitary. In TIDA cells, TRH caused a transition from phasic to tonic firing through combined pre- and postsynaptic effects. These findings suggest a model for prolactin regulation where a TIDA network switch from oscillations to sustained discharge converts dopamine from an antagonist at high concentrations to a functional agonist as dopamine output from the network decreases.
垂体激素催乳素会触发哺乳期母亲的泌乳。在非哺乳期条件下，催乳素的分泌受到下丘脑结节漏斗多巴胺（TIDA）神经元的强大抑制作用的抑制。尽管已经提出发射模式是神经内分泌控制的组成部分，但 TIDA 细胞的电行为仍然未知。我们证明，大鼠 TIDA 神经元以强大的 0.05 Hz 振荡有节奏地放电。振荡在神经元之间是相位锁定的，并且虽然它在化学突触传递阻断期间持续存在，但它被缝隙连接拮抗剂所消除。促甲状腺素释放激素（TRH）强烈刺激催乳素释放，这种作用被认为发生在垂体中。在 TIDA 细胞中，TRH 通过前突触和后突触的综合作用，引起从阵发性到紧张性放电的转变。这些发现为催乳素调节提出了一个模型，其中 TIDA 网络从振荡到持续放电的转变将多巴胺从高浓度的拮抗剂转换为功能性激动剂，因为网络的多巴胺输出减少。
