Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
J Neuroendocrinol. 2020 Nov;32(11):e12881. doi: 10.1111/jne.12881. Epub 2020 Aug 17.
The secretion of prolactin from the pituitary is negatively controlled by tuberoinfundibular dopamine (TIDA) neurones. The electrical properties of TIDA cells have recently been identified as a modulatory target of neurotransmitters and hormones in the lactotrophic axis. The role of the GABA receptor in this control has received little attention, yet is of particular interest because it may act as a TIDA neurone autoreceptor. Here, this issue was explored in a spontaneously active rat TIDA in vitro slice preparation using whole-cell recordings. Application of the GABA receptor agonist, baclofen, dose-dependently slowed down or abolished the network oscillations typical of this preparation. Pharmacological manipulations identify the underlying mechanism as an outward current mediated by G-protein-coupled inwardly rectifying K -like channels. In addition to this postsynaptic modulation, we describe a presynaptic modulation where GABA receptors restrain the release of glutamate and GABA onto TIDA neurones. Our data identify both pre- and postsynaptic modulation of TIDA neurones by GABA receptors that may play a role in the neuronal network control of pituitary prolactin secretion and lactation.
催乳素由垂体分泌，受结节漏斗多巴胺（TIDA）神经元的负向调控。最近发现，TIDA 细胞的电生理特性是催乳素轴神经递质和激素的调节靶点。然而，GABA 受体在这种调控中的作用却很少受到关注，因为它可能作为 TIDA 神经元的自身受体发挥作用。本研究采用全细胞膜片钳记录技术，在自发活动的大鼠 TIDA 体外脑片上，探讨了 GABA 受体在这一调控中的作用。GABA 受体激动剂巴氯芬可剂量依赖性地减缓或消除该脑片的网络振荡，提示 GABA 受体可能作为 TIDA 神经元的自身受体发挥作用。药理学操作表明，这种作用机制是由 G 蛋白偶联内向整流钾通道介导的外向电流。除了这种突触后调制外，我们还描述了一种突触前调制，其中 GABA 受体抑制谷氨酸和 GABA 释放到 TIDA 神经元上。我们的数据表明，GABA 受体对 TIDA 神经元既有突触前又有突触后的调制，可能在调节垂体催乳素分泌和哺乳的神经元网络中发挥作用。
