GABAergic inhibition through synergistic astrocytic neuronal interaction transiently decreases vasopressin neuronal activity during hypoosmotic challenge.
GABAergic inhibition through synergistic astrocytic neuronal interaction transiently decreases vasopressin neuronal activity during hypoosmotic challenge.
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DOI：
10.1111/ejn.12137
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发表时间：
2013-04
期刊：
影响因子：
--
通讯作者：
Hamilton KA
中科院分区：
文献类型：
--
作者：
Wang YF;Sun MY;Hou Q;Hamilton KA
The neuropeptide vasopressin is crucial to mammalian osmotic regulation. Local hypoosmotic challenge transiently decreases and then increases vasopressin secretion. To investigate mechanisms underlying this transient response, we examined effects of hypoosmotic challenge on the electrical activity of rat hypothalamic supraoptic nucleus (SON) vasopressin neurones using patch-clamp recordings. We found that 5 min exposure of hypothalamic slices to hypoosmotic solution transiently increased IPSC frequency and reduced firing rate of vasopressin neurones. Recovery occurred by 10 min exposure, even though the osmolality remained low. The GABAA receptor blocker, gabazine, blocked the IPSCs and the hypoosmotic suppression of firing. The gliotoxin l-aminoadipic acid blocked the increase in IPSC frequency at 5 min and the recovery of firing at 10 min, indicating astrocytic involvement in hypoosmotic modulation of vasopressin neuronal activity. Moreover, β-alanine, an osmolyte of astrocytes and GABA transporter inhibitor, blocked the increase in IPSC frequency at 5 min of hypoosmotic challenge. Confocal microscopy of immunostained SON sections revealed that astrocytes and magnocellular neurones both showed positive staining of vesicular GABA transporters (VGAT). Hypoosmotic stimulation in vivo reduced the number of VGAT-expressing neurones and increased co-localisation and molecular association of VGAT with glial fibrillary acidic protein that increased significantly by 10 min. By 30 min, neuronal VGAT labelling was partially restored and astrocytic VGAT was relocated to ventral portion while decreased in the somatic zone of the SON. Thus, synergistic astrocytic and neuronal GABAergic inhibition could ensure that vasopressin neurone firing is only transiently suppressed under hypoosmotic conditions.
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