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KMID : 1130320120550090387
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Korean Journal of Pediatrics
2012 Volume.55 No. 9 p.387 ~ p.393
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Excess of leptin inhibits hypothalamic KiSS-1 expression in pubertal mice
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Ahn Sung-Yeon
Yang Sei-Won
Lee Hee-Jae
Byun Jong-Seon
Om Ji-Yeon
Shin Choong-Ho
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Abstract
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Purpose: Leptin has been considered a link between metabolic state and reproductive activity. Defective reproductive function can occur in leptin-deficient and leptin-excessive conditions. The aim of this study was to examine the effects of centrally injected leptin on the hypothalamic KiSS-1 system in relation to gonadotropin-releasing hormone (GnRH) action in the initial stage of puberty.
Methods: Leptin (1 μg) was injected directly into the ventricle of pubertal female mice. The resultant gene expressions of hypothalamic GnRH and KiSS-1 and pituitary LH, 2 and 4 hours after injection, were compared with those of saline-injected control mice. The changes in the gene expressions after blocking the GnRH action were also analyzed.
Results: The basal expression levels of KiSS-1, GnRH, and LH were significantly higher in the pubertal mice than in the prepubertal mice. The 1-μg leptin dose significantly decreased the mRNA expression levels of KiSS-1, GnRH, and LH in the pubertal mice. A GnRH antagonist significantly increased the KiSS-1 and GnRH mRNA expression levels, and the additional leptin injection decreased the gene expression levels compared with those in the control group.
Conclusion: The excess leptin might have suppressed the central reproductive axis in the pubertal mice by inhibiting the KiSS-1 expression, and this mechanism is independent of the GnRH-LHestradiol feedback loop.
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KEYWORD
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Leptin, KiSS-1, Gonadotropin-releasing hormone, Luteinizing hormone, Puberty
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