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 alpha-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.