Evidence that TRH controls prolactin release from rat lactotrophs by stimulating a calcium influx.
Prolactin (PRL) release and intracellular free calcium concentration [Ca2+]i were measured in two populations of normal rat lactotrophs (light and heavy fractions) in culture. Spontaneous PRL release of heavy fraction cells was more sensitive to dihydropyridines (DHPs; Bay K 8644 and nifedipine) when compared to the light fraction lactotrophs. The stimulatory effect of thyrotropin-releasing hormone (TRH) on PRL release from heavy fraction cells was inhibited by Cd2+ and mimicked by Bay K 8644. Indo-1 experiments revealed that TRH-increased [Ca2+]i was reversibly inhibited by Cd2+. In a Ca(2+)-free EGTA-containing medium, TRH did not modify [Ca2+]i.
Guérineau
N C
NC
Laboratoire de Neurophysiologie, URA CNRS 1200, Université de Bordeaux, France.
Lledo
P M
PM
Verrier
D
D
Israel
J M
JM
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003470:Culture Media; D003593:Cytoplasm / Q000378:metabolism; D004095:Dihydropyridines / Q000494:pharmacology*; D005260:Female; D009543:Nifedipine / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D015220:Calcium Channels; D003470:Culture Media; D004095:Dihydropyridines; D002104:Cadmium; D013973:Thyrotropin-Releasing Hormone; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D011388:Prolactin; D009543:Nifedipine; D002118:Calcium