In vitro release of gonadotropin-releasing hormone from the brain preoptic-anterior hypothalamic region and pituitary of female goldfish.
In vitro release of gonadotropin releasing hormone (GnRH) from slices of the preoptic-anterior hypothalamic (P-AH) region and fragments of the pituitary of goldfish was studied using a static incubation system. Release of GnRH from both tissue preparations was stimulated by depolarizing concentrations of extracellular potassium ions (K+). Other putative secretagogues, calcium ionophore A23187 (1 microM), forskolin (100 microM), and prostaglandin E2 1 microM) also stimulated release of GnRH from both tissue preparations. Omission of Ca2+, or chelating the remaining remaining Ca2+ by EGTA (0.1 mM), abolished the release of GnRH stimulated by high K+ concentrations (60 mM), but did not reduce spontaneous release. Verapamil (1 microM), a voltage-sensitive calcium channel blocker, abolished the release of GnRH stimulated by high K+ or A21387 from both tissue preparations. The GnRH released in vitro from both the P-AH region and pituitary was concentrated by Sep-Pak and then separated by high-performance liquid chromatography. The major peak of the GnRH immunoreactivity was found to coelute with synthetic salmon GnRH [( Trp7,Leu8]-GnRH) and the minor peak with chicken GnRH-II [( Gln8]-GnRH). Dopamine (10 and 100 microM) inhibited GnRH release from both P-AH slices and pituitary fragments, while serotonin (1-100 microM) stimulated release from both. Norepinephrine (10-100 microM) stimulated GnRH release from P-AH slices but not from pituitary fragments. The results demonstrate that the release of GnRH from goldfish P-AH slices and pituitary fragments in vitro in response to various secretagogues and monoamines can be studied using a static incubation system.
Yu
K L
KL
Department of Zoology, University of Alberta, Edmonton, Canada.
Rosenblum
P M
PM
Peter
R E
RE
D000595:Amino Acid Sequence; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D006054:Goldfish / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007032:Hypothalamus, Anterior / Q000378:metabolism*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009638:Norepinephrine / Q000494:pharmacology; D010902:Pituitary Gland / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011301:Preoptic Area / Q000378:metabolism*; D011863:Radioimmunoassay; D012701:Serotonin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D005576:Colforsin; D012701:Serotonin; D007987:Gonadotropin-Releasing Hormone; D000001:Calcimycin; D014700:Verapamil; D015232:Dinoprostone; D011188:Potassium; D004298:Dopamine; D009638:Norepinephrine