Membrane effects of thyrotropin-releasing hormone and estrogen shown by intracellular recording from pituitary cells.
The effects of thyrotropin-releasing hormone and 17 beta-estradiol on the electrical membrane properties of a prolactin-secretin pituitary cell line (GH3/B6) were studied with intracellular microelectrode recordings. Of the cells tested, 50 percent were excitable and displayed calcium-dependent action potentials when depolarized. When injected directly on the membrane of an excitable cell, thyrotropin-releasing hormone and 17 beta-estradiol induced action potentials within 1 minute. The spiking activity was preceded by a progressive increase of the input resistance without any detectable change in the resting membrane polarization. The results reveal a rapid effect of both substances on the membrane of GH3/B6 cells. In the case of thyrotropin-releasing hormone, which has both a short-term effect on release of prolactin and a long-term effect on its synthesis, the induced electrical activity may be associated with the stimulation of prolactin production. The physiological implication of 17 beta-estradiol-induced, calcium-dependent spiking activity remains to be elucidated.
D000200:Action Potentials / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects*; D013268:Stimulation, Chemical; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D004958:Estradiol; D013973:Thyrotropin-Releasing Hormone