Seasonal fluctuations in pituitary gland and plasma levels of gonadotropic hormones in Rana

General and Comparative Endocrinology
J W KimH B Kwon

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 dybowskii 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. dybowskii, 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 were also 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 ...Continue Reading

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Citations

Jan 29, 2008·Zygote : the Biology of Gametes and Early Embryos·Inés RamosSilvia N Fernández
Jun 27, 2007·ILAR Journal·Robert K Browne, Kevin Zippel
Feb 3, 2006·Reproductive Biology and Endocrinology : RB&E·Robert K BrowneAndrew Kouba
Jun 23, 2006·Reproductive Biology and Endocrinology : RB&E·Robert K BrowneAndrew Kouba
Mar 30, 2007·Zygote : the Biology of Gametes and Early Embryos·G Sánchez ToranzoM I Bühler
Nov 26, 2016·Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology·Vladimir V Shakhparonov, Sergei V Ogurtsov
Oct 16, 2020·Journal of Experimental Zoology. Part A, Ecological and Integrative Physiology·Susana CisintInés Ramos
Jul 3, 2002·General and Comparative Endocrinology·L F Canosa, N R Ceballos
Sep 12, 2002·Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology·Qiong WuKazuhiro J Mori

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