IGF-1 administration to prepubertal female rats can overcome delayed puberty caused by maternal Pb exposure.
Because prepubertal female rats maternally exposed to lead (Pb) exhibit suppressed serum levels of insulin-like growth factor-1 (IGF-1) and delayed puberty, we investigated the ability of centrally administered IGF-1 to stimulate luteinizing hormone (LH) release in vivo and LH-releasing hormone (LHRH) release in vitro from maternally Pb-exposed prepubertal female rats. Additionally, we assessed whether IGF-1 replacement could affect the timing of female puberty. Results demonstrated that IGF-1 stimulated significantly LH release in both control and Pb-exposed animals. When median eminences from control and Pb-exposed females were incubated with rat IGF-1 in vitro, they responded similarly with significant peptide-induced LHRH release. Lastly, we showed IGF-1 replacement reversed the delay in puberty caused by Pb. These results indicate the central LHRH response to IGF-1 is intact and that Pb-induced delayed puberty is due, at least in part, to suppressed circulating IGF-1 available to the hypothalamus.
Pine
Michelle D
MD
Veterinary Integrative Biosciences, Texas A&M University, VMA Building MS 4458, College Station, 77843, USA.
Hiney
Jill K
JK
Dearth
Robert K
RK
Bratton
Gerald R
GR
Dees
W Les
WL
D000818:Animals; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007854:Lead / Q000097:blood / Q000633:toxicity*; D007986:Luteinizing Hormone / Q000378:metabolism; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011628:Puberty, Delayed / Q000139:chemically induced* / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
D007854:Lead; D007987:Gonadotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone