Effect of mammalian thyrotropin releasing hormone on prolactin secretion by bullfrog adenohypophyses in vitro.

The effects of the mammalian thyrotropin-releasing hormone (TRH) on the secretion of prolactin by bullfrog adenohypophysis in vitro were investigated in short-term incubation and 24-hr organ culture experiments. Prolactin in the medium or in the incubated tissue was measured by either polyacrylamide disc gel electrophoresis and densitometry or by a homologous radioimmunoassay. The TRH was consistently effective in promoting prolactin release in vitro in concentrations of 10 ng/ml to 10 μg/ml. The tripeptide also caused an increase in the tissue prolactin content over a wide range of concentrations. These results indicate that TRH may function as a prolactin-releasing factor in the bullfrog.