Contrasting effects of testicular and ovarian steroids upon muscarinic binding sites in the brain.

In adult rats, testosterone increases the saturation binding capacity of hypothalamic and amygdaloid membrane fragments for the muscarinic antagonist, N-methyl scopolamine. In contrast, both estradiol and progesterone decrease binding capacity. There are sexual differences in muscarinic binding capacity and these are dependent upon perinatal exposure to androgens.