Effects of cortisol on GABAA receptor-mediated responses compared in guinea-pig ileum and rat cuneate nucleus.
Submaximal contractions of the isolated guinea-pig ileum by the GABAA receptor agonist muscimol were enhanced by about 30% in the presence of 1-100 pM cortisol. At 10 nM cortisol, the enhancement was much less and, at 1 microM, the responses to muscimol were reduced by about 50%. Corticosterone had similar effects but it was 100-1000 times less potent. In contrast, submaximal depolarization responses of the slice preparation of the cuneate nucleus of the rat to muscimol were unaffected by 1 pM-1 nM cortisol and only slightly enhanced (about 15%) by 1 microM cortisol. Also, enhancements of 70-120% by 1 microM alphaxalone were undiminished in the presence of 1 microM cortisol. Thus, there is no evidence for a potent effect of cortisol on the GABAA receptor complex in the cuneate nucleus of the rat.
Andres-Trelles
F
F
Department of Pharmacology, School of Pharmacy, University of London, U.K.
Bibby
V
V
Lustman
S
S
Simmonds
M A
MA
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002529:Cerebellar Nuclei / Q000187:drug effects / Q000378:metabolism*; D003345:Corticosterone / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000494:pharmacology*; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*
D011963:Receptors, GABA-A; D009118:Muscimol; D000109:Acetylcholine; D003345:Corticosterone; D006854:Hydrocortisone