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Attenuated benzodiazepine-sensitive tonic GABAA currents of supraoptic magnocellular neuroendocrine cells in 24-h water-deprived rats.
- Source :
-
Journal of neuroendocrinology [J Neuroendocrinol] 2014 Jan; Vol. 26 (1), pp. 26-34. - Publication Year :
- 2014
-
Abstract
- In supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs), γ-GABA, via activation of GABAA receptors (GABAA Rs), mediates persistent tonic inhibitory currents (Itonic ), as well as conventional inhibitory postsynaptic currents (IPSCs, Iphasic ). In the present study, we examined the functional significance of Itonic in SON MNCs challenged by 24-h water deprivation (24WD). Although the main characteristics of spontaneous IPSCs were similar in 24WD compared to euhydrated (EU) rats, Itonic , measured by bicuculline (BIC)-induced Iholding shifts, was significantly smaller in 24WD compared to EU rats (P < 0.05). Propofol and diazepam prolonged IPSC decay time to a similar extent in both groups but induced less Itonic in 24WD compared to EU rats, suggesting a selective decrease in GABAA receptors mediating Itonic over Iphasic in 24WD rats. THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), a preferential δ subunit agonist, and L-655,708, a GABAA receptor α5 subunit selective imidazobenzodiazepine, caused a significantly smaller inward and outward shift in Iholding , respectively, in 24WD compared to EU rats (P < 0.05 in both cases), suggesting an overall decrease in the α5 subunit-containing GABAA Rs and the δ subunit-containing receptors mediating Itonic in 24WD animals. Consistent with a decrease in 24WD Itonic , bath application of GABA induced significantly less inhibition of the neuronal firing activity in 24WD compared to EU SON MNCs (P < 0.05). Taken together, the results of the present study indicate a selective decrease in GABAA Rs functions mediating Itonic as opposed to those mediating Iphasic in SON MNCs, demonstrating the functional significance of Itonic with respect to increasing neuronal excitability and hormone secretion in 24WD rats.<br /> (© 2014 British Society for Neuroendocrinology.)
- Subjects :
- Animals
Bicuculline pharmacology
Diazepam pharmacology
GABA Agonists pharmacology
GABA-A Receptor Antagonists pharmacology
Hypnotics and Sedatives pharmacology
Imidazoles pharmacology
Inhibitory Postsynaptic Potentials drug effects
Isoxazoles pharmacology
Male
Neuroendocrine Cells drug effects
Propofol pharmacology
Protein Subunits drug effects
Protein Subunits physiology
Rats
Supraoptic Nucleus drug effects
gamma-Aminobutyric Acid pharmacology
Inhibitory Postsynaptic Potentials physiology
Neuroendocrine Cells physiology
Receptors, GABA-A physiology
Supraoptic Nucleus cytology
Supraoptic Nucleus physiology
Water Deprivation physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1365-2826
- Volume :
- 26
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of neuroendocrinology
- Publication Type :
- Academic Journal
- Accession number :
- 24313753
- Full Text :
- https://doi.org/10.1111/jne.12123