| This study concerned the regulation of gonadotropin-releasing hormone (GnRH) in goldfish brain. A radioimmunoassay (RIA) for (Trp;The centrally active dopaminergic antagonist pimozide caused time and dose dependent increases in serum GtH levels and accumulation of GnRH in the olfactory bulbs, telencephalon and pituitary, through an apomorphine-sensitive dopaminergic mechanism. Male goldfish exposed to prostaglandin (PG)-treated females for one or two hours had significantly increased serum GtH levels and GnRH concentrations in discrete forebrain areas. These GtH and GnRH responses were abolished by sectioning of the olfactory tracts (OT), specifically the medial OT in the male goldfish. Pretreatment of male goldfish with pimozide potentiated the increases in serum GtH levels and caused a marked reduction of GnRH in the olfactory bulbs, telencephalon and pituitary in response to PG-treated females. The results together suggest that the central dopaminergic system has an inhibitory influence on the brain GnRH system and pituitary GtH secretion in normal and behaviourally-stimulated male goldfish.;Using an in vitro status incubation system, norepinephrine was found to stimulate GnRH release from slices of the preoptic-anterior hypothalamus through the ;Using a combined RIA and high performance liquid chromatography approach, the two molecular forms of GnRH in golfish brain and pituitary were characterized to be (Trp... |
