GABAergic modulation of noradrenaline release in the median preoptic nucleus area in the rat

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• 作者：Sakamaki ; Kazuhiro ; Nomura ; Masahiko ; Hatakenaka ; Satoko ; Miyakubo ; Hiroko ; Tanaka ; Junichi
• 关键词：Median preoptic nucleus ; Noradrenaline ; γ ; -Aminobutyric acid ; Muscimol ; Baclofen ; Fluid balance
• 刊名：Neuroscience Letters
• 出版年：2003
• 出版时间：May 15, 2003
• 年：2003
• 卷：342
• 期：1-2
• 页码：77-80
• 全文大小：115 K

文摘

Microdialysis was employed to investigate whether γ-aminobutyric acid (GABA) receptor mechanisms are involved in the regulation of noradrenaline (NA) release in the median preoptic nucleus (MnPO) in awake, freely moving rats. Perfusion with the GABA receptor antagonists as well as agonists was performed in the region of the MnPO through a microdialysis probe and dialysate levels of NA were measured. Perfusion with either bicuculline (10 and 50 μM), a GABA_A receptor antagonist, or phaclofen (10 and 50 μM), a GABA_B receptor antagonist, enhanced the release of NA in the MnPO area. Higher-dose perfusion with the GABA_A agonist muscimol (50 μM) or the GABA_B agonist baclofen (250 μM) decreased dialysate NA in the MnPO area. An iso-osmotic reduction of fluid volume following subcutaneous treatment with polyethylene glycol (PEG, 30 % , 5 ml) significantly increased the NA level in the MnPO area. The increased levels of NA caused by the PEG treatment were attenuated by perfusion with muscimol (10 μM), but not by baclofen (50 μM). These results show the participation of both GABA_A and GABA_B receptors in the modulation of the release of NA in the MnPO area, and imply that the GABA_A receptor mechanism may play an important role in the noradrenergic regulatory system of body fluid balance.