Differences in salmon GnRH and chicken GnRH-II contents in discrete brain areas of male and female rainbow trout according to age and stage of maturity.
We have developed sensitive and specific radioimmunoassays (RIA) for salmon gonadotropin-releasing hormone (sGnRH) and chicken GnRH-II (cGnRH-II). Synthetic sGnRH and cGnRH-II(2-10) were conjugated to bovine serum albumin and injected into rabbits to raise specific antisera. The antiserum against sGnRH showed cross-reactivities of 1.58 and 0.08% for cGnRH-II and lamprey GnRH, respectively. The antiserum against cGnRH-II showed cross-reactivities of 0.05 and 0.01% for sGnRH and lamprey GnRH, respectively. Both antisera were observed not to cross-react with mammalian GnRH and cGnRH-I or other peptide hormones. Synthetic sGnRH and cGnRH-II were iodinated using the chloramine-T method. The iodinated GnRH was purified by HPLC using a reverse-phase C18 column. The RIA system was developed as a double antibody method. Brain extracts of rainbow trout showed displacement curves which were parallel to the sGnRH and cGnRH-II standards in each RIA. HPLC analysis followed by RIA has revealed that rainbow trout brain contains two types of GnRH: sGnRH and cGnRH-II. Total sGnRH content in the brain was about three-fold higher than that of cGnRH-II. In the olfactory bulbs, telencephalon, optic tectum-thalamus, hypothalamus, and pituitary, sGnRH content (per region) was higher than cGnRH-II content, whereas cerebellum and medulla oblongata contained much more cGnRH-II than sGnRH. sGnRH content in the optic tectum-thalamus and pituitary was the highest in 1-year-old immature fish and 3-year-old mature fish, respectively. Medulla oblongata showed the highest cGnRH-II content in all groups. sGnRH concentrations (per milligram of protein) were high in the pituitary and intermediate in the olfactory bulbs, hypothalamus, and telencephalon. In all groups, the cGnRH-II concentration was high in the medulla oblongata, whereas the concentration in the olfactory bulbs and pituitary gland was below the detectable limit in most individuals.
Okuzawa
K
K
Department of Fisheries, Faculty of Agriculture, University of Tokyo, Japan.
Amano
M
M
Kobayashi
M
M
Aida
K
K
Hanyu
I
I
Hasegawa
Y
Y
Miyamoto
K
K
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002531:Cerebellum / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D007031:Hypothalamus / Q000737:chemistry / Q000378:metabolism; D007106:Immune Sera / Q000276:immunology; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry / Q000378:metabolism; D009830:Olfactory Bulb / Q000737:chemistry / Q000378:metabolism; D010902:Pituitary Gland / Q000737:chemistry / Q000378:metabolism; D011863:Radioimmunoassay; D012727:Sex Characteristics; D013477:Superior Colliculi / Q000737:chemistry / Q000378:metabolism; D013687:Telencephalon / Q000737:chemistry / Q000378:metabolism; D014337:Trout / Q000378:metabolism*
D007106:Immune Sera; D007987:Gonadotropin-Releasing Hormone