title: The role of insulin-like growth factor-I and growth factor-associated signal transduction pathways in estradiol and progesterone facilitation of female reproductive behaviors.
abstract: We are examining the role of insulin-like growth factor-I (IGF-I) and downstream signal transduction pathways associated with growth factors (e.g., mitogen-activated protein kinase, MAPK) in estradiol and progesterone facilitation of female reproductive behavior in rats. Brain IGF-I receptor activity is required for the long-term, priming actions of estradiol on the female reproductive axis. Infusions of an IGF-I receptor antagonist during estradiol priming blocks induction of hypothalamic alpha(1B)-adrenergic receptors and luteinizing hormone surges, and attenuates lordosis behavior. Infusion of MAPK and phosphatidylinositol-3-kinase inhibitors inhibitors during estradiol priming completely blocks hormone-facilitated lordosis. Because progestin receptors (PRs) can be phosphorylated and activated by MAPKs, growth factor signaling pathways may also participate in progesterone facilitation of reproductive behaviors. Infusion of a MAPK inhibitor in estradiol-primed rats blocks progestin facilitation and sequential inhibition of lordosis and proceptive behaviors. Interference with MAPK signaling also inhibits behavioral responses to cGMP and a delta-opioid agonist, both of which can activate MAPK in some cells. Thus MAPK is involved in the facilitation of lordosis and proceptive behaviors, perhaps by phosphorylation of hypothalamic PRs.
authors.affiliation: Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA. etgen@aecom.yu.edu
authors.forename: Anne M
authors.initials: AM
authors.lastname: Etgen
authors.forename: Oscar
authors.initials: O
authors.lastname: González-Flores
authors.forename: Brigitte J
authors.initials: BJ
authors.lastname: Todd
mesh_terms: D000818:Animals; D006152:Cyclic GMP / Q000502:physiology; D004958:Estradiol / Q000502:physiology*; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D016501:Neurites / Q000502:physiology; D009490:Neurosecretory Systems / Q000502:physiology; D011187:Posture; D011374:Progesterone / Q000502:physiology*; D051381:Rats; D011960:Receptors, Estrogen / Q000502:physiology; D017465:Receptors, Opioid, delta / Q000502:physiology; D012098:Reproduction / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D011960:Receptors, Estrogen; D017465:Receptors, Opioid, delta; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D020928:Mitogen-Activated Protein Kinases; D006152:Cyclic GMP