Differences in mGnRH and cGnRH-II contents in pituitaries and discrete brain areas of Rana rugulosa W. according to age and stage of maturity.
(1) In tadpoles, chicken-II gonadotropin-releasing hormone (cGnRH-II) could be measured in the brains before metamorphosis, but mammalian gonadotropin-releasing hormone (mGnRH) did not appear until the stage of metamorphosis, i.e. cGnRH-II appeared earlier than mGnRH during ontogenesis. (2) During the metamorphic climax, mGnRH content increased more rapidly than cGnRH-II; the content of mGnRH was about two times of that of cGnRH-II. (3) In juveniles and adults, the content of mGnRH and cGnRH-II, and the distribution pattern of mGnRH (but not cGnRH-II) in the brains and pituitaries changed with age and stages of gonadal development. mGnRH mainly distributed in the rostral brain areas, whereas cGnRH-II had a widespread distribution in the brain. (4) Both mGnRH and cGnRH-II were present in the pituitaries at each stage of maturity. The gonadotropin-releasing hormone (GnRH) content at sexually maturity was significantly higher than that at other stages of gonadal development, and the content of mGnRH was about 15-18 times of that of cGnRH-II. (5) These results suggest that both mGnRH and cGnRH-II are potentially involved in the direct regulation of pituitary gonadotropes, and mGnRH may be the major active form, cGnRH-II may also serve as a neurotransmitter or neuromodulator in the brain.
Yuanyou
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School of Life Science, Zhongshan University, Guangzhou 510275, People's Republic of China.
Haoran
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L
D000367:Age Factors; D000818:Animals; D001921:Brain / Q000502:physiology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis* / Q000494:pharmacology*; D007814:Larva / Q000235:genetics; D008297:Male; D008675:Metamorphosis, Biological / Q000502:physiology*; D010902:Pituitary Gland / Q000737:chemistry / Q000502:physiology*; D011898:Ranidae / Q000254:growth & development* / Q000502:physiology*
D007987:Gonadotropin-Releasing Hormone