Evidence for a pertussis toxin-sensitive signalling pathway in the dual action of angiotensin II on growth hormone release in pituitary cell aggregates.
In anterior pituitary cell aggregates cultured in the presence of the glucocorticoid dexamethasone (DEX) angiotensin II (AII) had a dual effect on growth hormone (GH) release. The peptide stimulated the release in aggregates from 2-week-old rats, whereas the peptide had an inhibitory effect in cultures from adult rats. Treatment of aggregates from adult rats with pertussis toxin (PT) reversed the inhibitory effect of AII on GH release in a stimulatory effect; PT treatment of aggregates from 18- to 20-day-old rats significantly enhanced the stimulation of GH release by AII. The effect of PT was seen only when DEX was added to the culture medium. The present data suggest that the glucocorticoid-dependent stimulus-effect coupling of AII on GH release involves both a stimulatory and an inhibitory component, the latter being abolished by PT, and that the stimulatory component predominates during immature life while the inhibitory one during adult life.
Robberecht
W
W
Laboratory of Cell Pharmacology, School of Medicine, University of Leuven, Belgium.
Denef
C
C
D000367:Age Factors; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002449:Cell Aggregation; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism*; D037342:Pertussis Toxin; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D010566:Virulence Factors, Bordetella; D000804:Angiotensin II; D003907:Dexamethasone; D013006:Growth Hormone; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins