ACh-induced inhibition of adenylyl cyclase and LH release in perifused pituitary cells. A–C, Effects of ACh on cAMP release in cultured pituitary cells. A, Inhibition of basal cAMP release by ACh. B, PTX sensitivity of 10 μm ACh-induced inhibition of cAMP release. C, ACh (10 μm)-induced inhibition of forskolin (1 μm) stimulated cAMP release. D, Effect of ACh on cAMP release in LβT2 cells. Horizontal bars indicate duration of ACh treatment. E, Effects of ACh on GnRH induced LH release. Inhibitory effect on GnRH-stimulated LH release was observed after pretreatment with ACh (10 μm) for 15 min. Inset shows a small increase in LH release triggered by ACh alone.