IMR Press / CEOG / Volume 42 / Issue 1 / DOI: 10.12891/ceog1786.2015

Clinical and Experimental Obstetrics & Gynecology (CEOG) is published by IMR Press from Volume 46 Issue 1 (2019). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with S.O.G.

Open Access Original Research
Leptin increases luteinizing hormone secretion of fasting female rats
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1 Department of Physiology and Pharmacology, Aristotle University of Thessaloniki
2 3rd Department of Obstetrics and Gynaecology, Aristotle University of Thessaloniki
3 Advanced Technological Educational Institute, Thessaloniki
4 Unit for Human Reproduction, 1st Department of Obstetrics and Gynaecology, Papageorgiou General Hospital, Aristotle University of Thessaloniki, Thessaloniki (Greece)
Clin. Exp. Obstet. Gynecol. 2015, 42(1), 18–21; https://doi.org/10.12891/ceog1786.2015
Published: 10 February 2015
Abstract
Purpose: To investigate whether leptin acts directly on the anterior hypophysis by influencing gonadotropin secretion in vivo. Materials and Methods: Cycling female rats were catheterised for frequent blood sampling and were either fasted or allowed free access to food. Stereotactic lesion of the medial preoptic area (MPOA) of the hypothalamus was performed in order to eliminate gonadotropin releasing hormone (GnRH) production. Leptin was administered at a dose of one mg/kg i.v. and blood samples were taken just before leptin administration and then after 30, 60, 90, 120, and 180 minutes. Plasma gonadotropin levels were determined. With completion of sampling, the brains were removed and the localisation of the lesions was verified histologically. Results: Leptin at one mg/kg induced an increase in luteinizing hormone (LH) secretion in fasting rats, both in those with a lesion and those with intact medial preoptic area with a peak occurring 90 minutes after infusion. The augmenting effect was more prominent when the hypothalamus was intact. There was no effect in fed animals with or without lesion. Similarly, no effect was observed on follicle stimulating hormone (FSH) levels in any of the experimental groups. Conclusions: Leptin acts directly on the hypophysis enhancing LH but not FSH secretion. Nutritional state influences leptin’s effect on the hypothalamus and the hypophysis.
Keywords
Leptin
Rats
Medial preoptic area
Hypophysis
Gonadotropins
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