Mecamylamine blockade of nicotine responses: evidence for two brain nicotinic receptors.
Mice of two inbred strains, DBA and C3H, were pretreated with mecamylamine before challenge with nicotine. Mecamylamine blocked nicotine-induced seizures, enhanced startle, and alterations in respiratory rate, Y-maze activity, heart rate and body temperature. Mecamylamine blocked nicotine-induced seizures and enhanced startle with IC50 values of less than 0.1 mg/kg. The other nicotine effects were blocked by mecamylamine with IC50 values between 0.8 and 2.3 mg/kg. Strain differences in sensitivity to mecamylamine blockade were also detected. These results suggest that nicotine elicits its effects at two receptors, which may be those labeled with [125I]-alpha-bungarotoxin and with [3H]-nicotine.
D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000187:drug effects*; D001923:Brain Chemistry; D002038:Bungarotoxins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007457:Iodine Radioisotopes; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology*; D051379:Mice; D008809:Mice, Inbred C3H; D008811:Mice, Inbred DBA; D009538:Nicotine / Q000494:pharmacology*; D011978:Receptors, Nicotinic / Q000032:analysis* / Q000187:drug effects; D013216:Reflex, Startle / Q000187:drug effects; D013045:Species Specificity
D002038:Bungarotoxins; D007457:Iodine Radioisotopes; D011978:Receptors, Nicotinic; D008464:Mecamylamine; D009538:Nicotine