Scopolamine inhibition of female sexual behavior in rhesus monkeys (Macacamulatta)

Previous research supports the activational role of central cholinergic mec hanisms in rodent female sexual behavior. This experiment examined if simil ar central cholinergic mechanisms facilitate female rhesus monkey (Macaca m ulatta) sexual behavior. Eight ovariectomized female rhesus monkeys receive d daily estradiol benzoate priming (5 mu g/kg, SC). After 13-16 days of est rogen priming, animals were injected intravenously with either the choliner gic antagonist, scopolamine (0.70 mg/kg), or saline vehicle (1 ml/kg). Resu lts indicate that the female preceptive behaviors of noncontact presentatio ns significantly decreased 15-45 min after scopolamine injection. Scopolami ne inhibition was sustained up to 75 min only after 15 days of estrogen pri ming. Scopolamine did not significantly reduce other female sexual behavior s. Additionally, significant decreases in the number of mounts and intromis sions, but not hip touches, were displayed by males exposed to scopolamine- treated females. This research suggests the possibility of a central cholin ergic mechanism regulating female sexual behavior in rhesus monkeys. Howeve r, the general nature and duration of the cholinergic regulation of primate female sexual behavior differs substantially when compared to rodent behav ior. (C) 1999 Elsevier Science Inc.