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Titolo:
SEASONAL FLUCTUATIONS IN PITUITARY-GLAND AND PLASMA-LEVELS OF GONADOTROPIC-HORMONES IN RANA
Autore:
KIM JW; IM WB; CHOI HH; ISHII S; KWON HB;
Indirizzi:
CHONNAM NATL UNIV,DEPT BIOL KWANGJU 500757 SOUTH KOREA CHONNAM NATL UNIV,HORMONE RES CTR KWANGJU 500757 SOUTH KOREA WASEDA UNIV,DEPT BIOL TOKYO JAPAN
Titolo Testata:
General and comparative endocrinology
fascicolo: 1, volume: 109, anno: 1998,
pagine: 13 - 23
SICI:
0016-6480(1998)109:1<13:SFIPAP>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
OVARIAN FOLLICLES; BUFO-JAPONICUS; SEX STEROIDS; LUTEINIZING-HORMONE; TESTICULAR ACTIVITY; BREEDING-SEASON; ANNUAL CYCLE; GREEN FROG; ESCULENTA; TOAD;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
24
Recensione:
Indirizzi per estratti:
Citazione:
J.W. Kim et al., "SEASONAL FLUCTUATIONS IN PITUITARY-GLAND AND PLASMA-LEVELS OF GONADOTROPIC-HORMONES IN RANA", General and comparative endocrinology, 109(1), 1998, pp. 13-23

Abstract

Changes in plasma and pituitary levels of two gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), in male and female Korean frogs (Rana dybowshii and Rana nigromaculata) were examined. Plasma levels of LH and FSH were measured by radioimmunoassay using antibodies raised against bullfrog LH and FSH. In male and female R.dybowshii, plasma concentrations of LH were low in early hibernation (October-January) and increased to high levels by late hibernation, when breeding occurs (late February-early March). Plasma FSH levels werealso higher in the breeding period than during hibernation in male and female animals, but absolute levels of FSH were much lower than those of LH. In females, pituitary LH levels were higher in early hibernation, whereas pituitary FSH in females and pituitary LH and FSH in males changed little during hibernation. Plasma LH levels of frogs having uterine eggs or in amplexus were much higher (> 25 ng/ml) than those of frogs with unovulated follicles (December) (<8 ng/ml) or frogs that had already spawned (<11 ng/ml). In R. nigromaculata, plasma LH and FSH levels of females collected during hibernation (October-May) were relatively low; however, following hibernation, plasma LH and FSH levelswere markedly elevated for a short period. Thus, these animals exhibit a clear gonadotropin surge prior to ovulation and spawning. Soon after spawning, however, gonadotropin levels dropped to basal levels. Following spawning in females, levels of FSH increased steadily and rapidfollicle growth occurred until August. By September, FSH had dropped to basal levels. In males, a sharp elevation of LH and FSH levels occurred during the short breeding period followed by a second increase inAugust, when early stages of spermatogenesis were evident. (C) 1998 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 06:25:13