Acetylcholine modulates the effect of ovarian steroids on glutamic acid decarboxylase activity in the rat fallopian tube

Glutamic acid decarboxylase (GAD) activity was measured in the oviduct of normal rats in diestrous and in rats ovariectomized (OVX) seven days before. OVX induced a significant decrease of GAD activity in the Fallopian tube. This effect was completely reversed by coadministration of estradiol benzoate + progesterone (E + P). Simultaneous injection of atropine, but not of α-methyl-para-tyrosine or labetalol, completely prevented the activation of GAD induced by ovarian sterois. Moreover. prostigmin significantly potentiated the action of E + P on GAD activity in the rat oviduct. These data clearly suggest the participation of acetylcholine in the mecanisms whereby ovarian steroids regulate GAD activity in the rat Fallopian tube.