Display options
Share it on
Full text links
HighWire Free PMC Article

J Pharmacol Exp Ther. 1990 Aug;254(2):528-38.

Site-specific enhancement of gamma-aminobutyric acid-mediated inhibition of neural activity by ethanol in the rat medial septal area.

The Journal of pharmacology and experimental therapeutics

B S Givens, G R Breese

Affiliations

  1. Neurobiology Curriculum, University of North Carolina, School of Medicine, Chapel Hill.

PMID: 2166794 PMCID: PMC3010747
Free PMC Article

Abstract

Because of uncertainty concerning the interaction of ethanol with gamma-aminobutyric acid (GABA) receptor-mediated events, the present work was designed to investigate the effect of ethanol on GABA transmission in the rat septal area using behavioral and electrophysiological techniques. Microinjection of the GABAA agonist muscimol into the medial septal area (MSA) enhanced, and bicuculline administration antagonized, ethanol-induced impairment of the aerial righting reflex. Microinjection of these drugs into the lateral septum (LSi) did not influence this measure of ethanol-induced sedation. Furthermore, intraseptal injections of muscimol or bicuculline in saline-treated rats had no effect on the aerial righting reflex. These data suggest that the MSA plays a critical modulatory role in the sedative actions of ethanol. To assess the effect of ethanol on muscimol responses in the MSA and LSi at the cellular level, GABA was applied by iontophoresis to rhythmically bursting neurons of the MSA and to cells in the LSi. The magnitude of the resultant inhibition by GABA on these cells was assessed before and after systemic administration of ethanol. Ethanol enhanced GABA-mediated inhibition of MSA neural activity, but did not alter GABA-mediated inhibition of cellular activity in the LSi. In contrast, the inhibition of cellular activity in the MSA, caused by a maximally effective concentration of the benzodiazepine flurazepam, was not altered by ethanol. Other work in the MSA demonstrated that electrical stimulation of the fimbria caused an inhibition of ongoing single unit activity that was reduced by concurrent application of bicuculline. The duration of this electrically elicited inhibition in the MSA was enhanced after ethanol injection and then recovered to base-line levels. In addition, ethanol (1.5 mg/kg) caused an enhancement of the inhibition induced by nipecotic acid, a GABA uptake inhibitor. These findings demonstrate that GABA-mediated neural inhibition is enhanced by ethanol in the MSA but not the LSi, indicating that the actions of ethanol on GABA-induced inhibition can be site specific. It is proposed that the cellular action of ethanol may depend upon a specific molecular composition of the GABA receptor complex which may vary at selected sites in the brain.

Similar articles

Show all 7 similar articles

References

  1. J Pharmacol Exp Ther. 1990 Apr;253(1):95-103 - PubMed
  2. Life Sci. 1988;42(14):1385-93 - PubMed
  3. Annu Rev Neurosci. 1985;8:21-44 - PubMed
  4. Recent Dev Alcohol. 1987;5:313-25 - PubMed
  5. Science. 1980 Aug 8;209(4457):708-10 - PubMed
  6. Neurosci Biobehav Rev. 1983 Spring;7(1):87-95 - PubMed
  7. Electroencephalogr Clin Neurophysiol. 1979 Dec;47(6):752-4 - PubMed
  8. Brain Res Bull. 1986 Jul;17(1):123-6 - PubMed
  9. Alcohol Clin Exp Res. 1989 Oct;13(5):680-5 - PubMed
  10. J Pharmacol Exp Ther. 1981 Feb;216(2):306-14 - PubMed
  11. Psychopharmacology (Berl). 1982;78(1):71-5 - PubMed
  12. Eur J Pharmacol. 1983 Apr 22;89(1-2):53-62 - PubMed
  13. Brain Res. 1985 Aug 5;340(1):135-42 - PubMed
  14. Brain Res. 1983 Mar 21;263(2):223-41 - PubMed
  15. J Pharmacol Exp Ther. 1980 Feb;212(2):203-10 - PubMed
  16. J Pharmacol Exp Ther. 1976 Mar;196(3):594-604 - PubMed
  17. J Pharmacol Exp Ther. 1987 Apr;241(1):346-53 - PubMed
  18. J Neurochem. 1981 Jul;37(1):1-13 - PubMed
  19. Brain Res Bull. 1986 May;16(5):573-96 - PubMed
  20. Neuron. 1989 Sep;3(3):327-37 - PubMed
  21. Life Sci. 1983 Jan 17;32(3):165-79 - PubMed
  22. Science. 1986 Jan 10;231(4734):161-3 - PubMed
  23. J Pharmacol Exp Ther. 1982 Dec;223(3):750-6 - PubMed
  24. Proc Natl Acad Sci U S A. 1986 Jun;83(11):4071-5 - PubMed
  25. Life Sci. 1986 Nov 24;39(21):2005-15 - PubMed
  26. Alcohol Drug Res. 1985-1986;6(6):423-9 - PubMed
  27. J Pharmacol Exp Ther. 1988 Aug;246(2):558-64 - PubMed
  28. Drug Alcohol Depend. 1979 May-Jul;4(3-4):321-6 - PubMed
  29. Pharmacol Biochem Behav. 1984 Jul;21(1):145-9 - PubMed
  30. Brain Res. 1987 Jun 23;414(1):22-34 - PubMed
  31. Science. 1986 Dec 5;234(4781):1243-7 - PubMed
  32. J Physiol. 1986 Oct;379:309-30 - PubMed
  33. Brain Res. 1988 Jul 12;455(2):377-80 - PubMed
  34. Science. 1982 Jan 15;215(4530):306-9 - PubMed
  35. Brain Res. 1984 Nov 26;322(2):261-7 - PubMed
  36. J Neurosci. 1987 Jan;7(1):48-54 - PubMed
  37. J Physiol. 1974 Mar;237(3):625-33 - PubMed
  38. J Pharmacol Exp Ther. 1981 Nov;219(2):489-95 - PubMed

Substances

MeSH terms

Publication Types

Grant support

LinkOut - more resources