Estradiol modulates the LH release response to N-methyl-D-aspartate in adult female rats: studies on hypothalamic luteinizing hormone-releasing hormone and neurotransmitter release.
We investigated the effect of ovariectomy (OVX) and subsequent estradiol benzoate (EB) treatment upon the N-methyl-D-aspartate (NMDA)-induced LH secretion in adult female rats. Furthermore, the release of LHRH, norepinephrine (NE), dopamine (DA), 5-hydroxyindoleacetic acid (5-HIAA) and gamma-aminobutyric acid (GABA) from superfused hypothalamic fragments explanted from OVX and OVX-EB rats was determined. Two weeks after OVX, animals received EB (100 mg/kg) s.c., or oil vehicle (OVX-EB or OVX groups, respectively). Two days thereafter, at 09.00 h, NMDA (15 or 30 mg/kg) was given as an i.v. bolus; blood samples were drawn before and 10 min after drug administration. In OVX rats, NMDA had no significant effect on LH levels, whereas it stimulated LH release in OVX-EB animals at both doses tested (315 and 362% from basal values, p < 0.001). For hypothalamic superfusion studies OVX and OVX-EB animals were decapitated at 09.00 h, and the mediobasal hypothalami (MBH) dissected on ice. NMDA (10(-4) M) was added to the superfusion medium for a 10 min period. Basal LHRH release (OVX: 1.41 +/- 0.18; OVX-EB: 1.59 +/- 0.28 pg/10 min/MBH) was significantly (p < 0.05) enhanced by NMDA (OVX: 2.97 +/- 0.95; OVX-EB: 2.80 +/- 0.61 pg/10 min/MBH). EB treatment had no significant effect on basal or NMDA-induced LHRH output.(ABSTRACT TRUNCATED AT 250 WORDS)
Arias
P
P
Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Jarry
H
H
Leonhardt
S
S
Moguilevsky
J A
JA
Wuttke
W
W
D000818:Animals; D004298:Dopamine / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D007986:Luteinizing Hormone / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley
D018377:Neurotransmitter Agents; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D006897:Hydroxyindoleacetic Acid; D016202:N-Methylaspartate; D007986:Luteinizing Hormone; D004298:Dopamine; D009638:Norepinephrine