INVOLVEMENT OF MUSCARINIC RECEPTORS IN THE CONTROL OF FEMALE PUBERTY IN THE RAT

Immature female rats (21 days of age) were chronically intraperitoneal ly treated with guanethidine or muscarinic agents. The effects on the timing of puberty and ovarian wet weight, protein and total RNA and DN A contents were studied. While guanethidine (20.0 mg/kg/day) was ineff ective, trihexyphenidyl and especially propantheline (15.0 mg/kg/day) delayed vaginal opening (by 23%) and the first vaginal oestrus (by 28% ), and lowered ovarian weight (by 37%) and other ovarian growth parame ters. Carbachol (0.2 mg/kg/day) reversed the effects of propantheline. Thus, in contrast to the adrenergic system, the cholinergic system ap pears to substantially contribute to the accurate onset of female pube rty and ovarian growth in the rat.