Nongenomic actions of testosterone on a subset of lactotrophs in the male rat pituitary.
Rapid, nongenomic effects of testosterone on PRL release in vitro were investigated. Anterior pituitary tissue from adult male rats was stimulated in vitro for 5 or 20 min with testosterone (T; 1 or 100 nM) or testosterone-BSA (T-BSA; 1 or 100 nM) with or without 1.2 mM tannic acid, which enables visualization of secretory granule exocytosis. Within 5 min, both concentrations of T and T-BSA stimulated exocytosis from type 2 lactotrophs (characterized by small spherical granules), but not from type 1 lactotrophs (characterized by large polymorphic granules). The effects of T on type 2 lactotrophs could be blocked by preincubation with dopamine (500 nM), but were not time or concentration dependent, and could not be inhibited by 1) removal of extracellular Ca2+, 2) the L-type Ca2+ channel blocker nifedipine (100 nM), 3) the Ca2+-adenosine triphosphatase inhibitor thapsigargin (150 nM), 4) the PKC inhibitor retinal (10 microM), or 5) the gamma-aminobutyric acidA chloride channel blocker picrotoxin (100 microM). T-BSA (0.1 nM to 1 microM) for 5 or 20 min also caused an increased release of immunoreactive PRL into the medium compared with control incubations. T and T-BSA did not stimulate exocytosis from gonadotrophs or cause LH release. In conclusion, we report for the first time a rapid, nongenomic effect of T on PRL secretion.
Christian
H C
HC
Department of Human Anatomy and Genetics, University of Oxford, United Kingdom.
Rolls
N J
NJ
Morris
J F
JF
D000818:Animals; D002118:Calcium / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002417:Cattle; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects; D005404:Fixatives; D047348:Hydrolyzable Tannins; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D010902:Pituitary Gland / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D011388:Prolactin / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013739:Testosterone / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D005404:Fixatives; D047348:Hydrolyzable Tannins; D012710:Serum Albumin, Bovine; D013739:Testosterone; D011388:Prolactin; D007986:Luteinizing Hormone; D011493:Protein Kinase C; D000252:Calcium-Transporting ATPases; D002118:Calcium