Modulation of anterior pituitary luteinizing hormone response to gonadotropin-releasing hormone by insulin-like growth factor I in vitro.
OBJECTIVE
To investigate how much insulin-like growth factor I may modulate the LH response to GnRH.


METHODS
In primary cultures of male rat anterior pituitary cells, the LH response to GnRH (10(-9) M) was evaluated after a 24-hour preincubation with medium alone, IGF-I (1, 5, 10, 15 nM), polyclonal antibody anti-IGF-I (Ab-anti-IGF-I), (1:3,000; 1:10,000), or rabbit serum (1:3,000; 1:10,000) as control.


METHODS
Gonadotropin-releasing hormone-induced LH release from primary cultures of male rat anterior pituitary cells.


RESULTS
Insulin-like growth factor I induces a dose-dependent stimulus on the LH response to GnRH. Insulin-like growth factor I at doses of 10 and 15 nM exerted a maximal stimulus, increasing the LH response to GnRH by 30%. The Ab-anti-IGF-I at both dilutions reduced the LH response to GnRH by 30%. No effect was exerted by rabbit serum.


CONCLUSIONS
Present data indicate that IGF-I may enhance the normal LH response to GnRH from rat anterior pituitary glands, suggesting important influences of this growth factor in the modulation of anterior pituitary LH release.
Soldani
R
R
University of Cagliari, Italy.
Cagnacci
A
A
Paoletti
A M
AM
Yen
S S
SS
Melis
G B
GB
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007987:Gonadotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone