Osmotic perception of GABAergic synaptic transmission in the supraoptic nucleus of rats
Osmotic perception of GABAergic synaptic transmission in the supraoptic nucleus of rats
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大鼠视上核 GABA 能突触传递的渗透感知
DOI：
10.1016/j.ibror.2020.06.007
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发表时间：
2020
期刊：
影响因子：
2.6
通讯作者：
Ueta Yoichi
中科院分区：
文献类型：
--
作者：
Ohbuchi Toyoaki;Saito Takeshi;Yokoyama Toru;Hashimoto Hirofumi;Maruyama Takashi;Suzuki Hideaki;Ueta Yoichi
细胞外渗透压在控制神经元的激活中起着至关重要的作用。高渗刺激通过突触前末梢上的辣椒素不敏感的瞬时受体电位香草酸（TRPV）1通道调节视上核（SON）大细胞神经分泌细胞（MNCs）和加压素（VP）神经元的突触能输入。然而，目前还不清楚渗透刺激是否调节GABA能输入到仅含有SON和核周区的打孔切片内的VP分泌神经元。我们采用全细胞膜片钳技术研究了不同渗透压条件对大鼠视上核VP-1细胞上GABA能突触后电流的影响。我们发现，在高渗溶液中孵育2小时降低了mGPSC向SON推定VP神经元的频率和振幅，而当外部渗透压从等渗变为低渗时，mGPSC不受影响。有趣的是，我们发现从高渗到低渗环境的变化增加了mGPSC的频率。这种作用不依赖于TRPV 4。我们推测，两种协调机制可能在VP的广泛生理功能调节中起重要作用：1)在高渗条件下通过脑源性神经营养因子（BDNF）诱导的酪氨酸激酶B受体介导的信号传导对GABA A受体特性的调节，和2）在低渗条件下细胞肿胀诱导的全细胞阴离子电流的激活。
Extracellular osmolality plays a crucial role in controlling the activation of neurons. Hypertonic stimulation modulates glutamatergic inputs to the supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs) putative vasopressin (VP) neurons through capsaicin-insensitive transient receptor potential vanilloid (TRPV) 1 channels on the presynaptic terminals. However, it remains unclear whether osmotic stimulation modulates GABAergic inputs to VP-secreting neurons within punched-out slices containing only the SON and the perinuclear zone.To answer this question, we studied the effects of various osmotic conditions on the miniature GABAergic postsynaptic currents (mGPSCs) using the whole-cell patch-clamp technique on rat SON putative VP-secreting neurons in small slice preparations.We revealed that incubation in hypertonic solution for 2 h reduced both the frequency and amplitude of the mGPSCs to the SON putative VP neurons, whereas the mGPSCs were unaffected when the external osmolality was changed from isotonic to hypotonic. Of interest, we found that changing from a hypertonic to hypotonic environment increased the frequency of the mGPSCs. This effect was independent of TRPV4.We hypothesize that two coordinated mechanisms may play an important role in the regulation of a wide range of physiological functions of VP.: 1) the modulation of GABAAreceptor properties by brain-derived neurotrophic factor (BDNF)-induced tyrosine kinase B receptor-mediated signaling under hypertonic conditions, and 2) cell swelling-induced activation of whole-cell anion currents under hypotonic conditions.