Adrenalectomy Potentiates Noradrenergic Suppression of GABAergic Transmission in Parvocellular Neurosecretory Neurons of Hypothalamic Paraventricular Nucleus

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Yang, Jian Hua; Li, Long Hua; Shin, Seung Yub; Lee, Sora; Lee, So Yeong; Han, Seong Kyu; Ryu, Pan Dong
Issue Date
American Physiological Society
J Neurophysiol 99: 514-523, 2008
Glucocorticoids are known to regulate both the noradrenergic and GABAergic inputs to the paraventricular nucleus (PVN). However, little is known about the effects of glucocorticoids on the interaction of these two input systems. Here we examined the effects of bilateral adrenalectomy (ADX) on the noradrenergic modulation of GABAergic transmission in the type II PVN neurons labeled with a retrograde dye injected into the pituitary stalk. Noradrenaline either reduced or augmented the frequency of spontaneous inhibitory postsynaptic current (sIPSC) without changing the amplitude and decay time constant. These effects were blocked by 2A- and 1A/1L-adrenoceptor antagonists, respectively. ADX increased the proportion of the neurons showing the noradrenergic reduction and the extent of reduction in the IPSC frequency. The ADX-induced changes were reversed by supplementation of ADX rats with corticosterone (10-mg pellet). ADX also potentiated the noradrenergic reduction in the frequency of miniature IPSC and paired-pulse facilitation of evoked IPSC. BRL 44408 (3 µM), a 2A-adrenoceptor antagonist, blocked the noradrenergic reduction in ADX rats. Corticotropin-releasing hormone and/or vasopressin transcripts were detected in neurons displaying noradrenergic augmentation or reduction of IPSC frequency. ADX enhanced the proportion of neurons expressing corticotropin-releasing hormone. Collectively, the results suggest that depletion of corticosterone by ADX markedly potentiates the noradrenergic suppression of GABAergic transmission mediated by the 2A-adrenoceptors on the GABAergic terminals in the parvocellular neurosecretory PVN neurons. These results may provide a novel synaptic mechanism for the glucocorticoid-induced plasticity in the noradrenergic modulation of neuroendocrine function of the PVN.
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College of Veterinary Medicine (수의과대학)Dept. of Veterinary Medicine (수의학과)Journal Papers (저널논문_수의학과)
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