Methylmercury modulates GABAA receptor complex differentially in rat cortical and cerebellar membranes in vitro.
Effects of methylmercury (MetHg) on the specific [3H]flunitrazepam binding were studied in rat cortical and cerebellar P2-fractions in vitro. MetHg did not affect significantly the specific [3H]flunitrazepam binding in unwashed P2-fraction but increased it marginally (by 16%) at 100 microM in washed P2-fraction, in both brain regions. Muscimol (3 microM), a GABAA agonist, stimulated the [3H]flunitrazepam binding by 30% to 50% depending on the brain region. In washed cerebellar membranes the enhancing response of muscimol was 10 to 14% lower after preincubation of the tissue with MetHg but in cerebral cortex MetHg did not modulate the muscimol response at all. The results indicate that Met-Hg may have region specific effects on GABAA receptors in vitro and the effect may depend on the occupational state of the GABA binding domain of the receptor complex.
Komulainen
H
H
Department of Pharmacology and Toxicology, University of Kuopio, Finland.
Keränen
A
A
Saano
V
V
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D005445:Flunitrazepam / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008767:Methylmercury Compounds / Q000494:pharmacology*; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D009928:Organ Specificity; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism*
D008767:Methylmercury Compounds; D011963:Receptors, GABA-A; D009118:Muscimol; D005445:Flunitrazepam; C004925:methylmercuric chloride