Effect of thyreotrope-releasing hormone (TRH) on prolactin turnover in culture.
A kinetic study of the influence of thyreotrope-releasing hormone (TRH) on prolactin turnover and synthesis by a new rat pituitary prolactin cell line (SD1) has been performed by means of pulse-chase experiments. After a 10-min [3H]leucine pulse, the chase was carried out in the presence or absence of TRH (54 nM), cycloheximide (3.6 X 10(-5)M) and/or [14C]-proline. The prolactin content of the cells in the medium was estimated using a radioimmunoassay technique. The specific radioactivity of prolactin in the medium was estimated after its isolation by disc gel electrophoresis. This kinetic study demonstrated, firstly, a rapid intracellular transit of newly synthesized prolactin (15 + 10 min or less); secondly, the existence of at least two intracellular prolactin pools; thirdly, a rapid effect of TRH on release of stored prolactin, which is independent of de novo protein synthesis, and fourthly, a delayed stimulating effect of TRH on prolactin synthesis.
D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D003513:Cycloheximide; D007930:Leucine