Early postnatal ethanol intubation blunts GABA A receptor up-regulation and modifies 3α-hydroxy-5α-pregnan-20-one sensitivity in rat MS/DB neurons
Previously we found postnatal binge-like ethanol exposure using an artificial-rearing method in the rat delayed developmental up-regulation of GABA A receptors (GABA ARs) in both medial septum/diagonal band (MS/DB) and cerebellar Purkinje neurons. In the present study, the impact of ethanol on devel...
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Published in | Brain research. Developmental brain research Vol. 130; no. 1; pp. 25 - 40 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
23.09.2001
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Subjects | |
Online Access | Get full text |
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Summary: | Previously we found postnatal binge-like ethanol exposure using an artificial-rearing method in the rat delayed developmental up-regulation of GABA
A receptors (GABA
ARs) in both medial septum/diagonal band (MS/DB) and cerebellar Purkinje neurons. In the present study, the impact of ethanol on developing GABA
ARs in MS/DB neurons was further tested under conditions not requiring anesthesia or maternal deprivation. Nursing rat pups received ethanol (4.5–5.25 g/kg/day) on postnatal days (PD) 4–9, which was administrated manually by oral intragastric intubation. This treatment caused dose-dependent blunting of peak GABA
A receptor whole cell currents in acutely dissociated MS/DB cells on PD 12–15. The threshold with oral intubation was slightly higher than previously observed for artificial-rearing (4.9 vs. 4.5 g/kg/day). The previously observed reduced sensitivity of GABA
ARs to Zn
2+-inhibition after ethanol was not found with the intubation model. In studies only carried out using the intubation method, 3α-hydroxy-5α-pregnan-20-one (3α-OH-DHP) caused an allosteric concentration-dependent potentiation of currents activated by non-saturated concentrations of GABA. A bicuculline sensitive direct activation of GABA
ARs also occurred with higher concentrations of 3α-OH-DHP alone. Ethanol intubation up-regulated allosteric neurosteroid potentiation with low concentrations of GABA, but did not change direct agonist actions of 3α-OH-DHP. Finally, 3α-OH-DHP did not prime ethanol insensitive GABA
ARs to become sensitivity to acute ethanol potentiation. These results indicate ethanol consistently blunts postnatal GABA
A receptor up-regulation across early postnatal binge-type ethanol exposure models and may increase positive modulation of GABA
A receptors by endogenous neurosteroids. |
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ISSN: | 0165-3806 |
DOI: | 10.1016/S0165-3806(01)00194-8 |