Effect of food deprivation and leptin repletion on the plasma levels of estrogen (E2) and NADPH-d reactivity in the ventromedial and arcuate nuclei of the hypothalamus in the female rats

The exact role of leptin in fasting has not been completely elucidated. To determine whether leptin can act in fasting to influence plasma estrogen levels and nitric oxide synthase reactivity in food regulating centers of the brain, we fasted female rats for 4 days and treated them i.p. with vehicle...

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Published in:	Brain research Vol. 887; no. 1; pp. 70 - 79
Main Authors:	Otukonyong, Effiong Edet, Okutani, Fumino, Takahashi, Seiichi, Murata, Takuya, Morioka, Nobuyuki, Kaba, Hideto, Higuchi, Takashi
Format:	Journal Article
Language:	English
Published:	London Elsevier B.V 22-12-2000 Amsterdam Elsevier New York, NY
Subjects:	Animals Arcuate nucleus Arcuate Nucleus of Hypothalamus - drug effects Arcuate Nucleus of Hypothalamus - metabolism Biological and medical sciences Body Weight - drug effects Body Weight - physiology Drinking - drug effects Drinking - physiology Eating - drug effects Eating - physiology Estrogen Estrogens - blood Fasting Feeding. Feeding behavior Female Food Deprivation - physiology Fundamental and applied biological sciences. Psychology Leptin Leptin - blood Leptin - pharmacology Mice NADPH Dehydrogenase - metabolism Nitric oxide synthase Nitric Oxide Synthase - drug effects Nitric Oxide Synthase - metabolism Proestrus - metabolism Rats Rats, Wistar Ventromedial Hypothalamic Nucleus - drug effects Ventromedial Hypothalamic Nucleus - metabolism Ventromedial hypothalamus Vertebrates: anatomy and physiology, studies on body, several organs or systems Ventromedial hypothalamus Fasting Arcuate nucleus Leptin Estrogen Endocrine and autonomic regulation Nitric oxide synthase Rat Enzyme Rodentia Central nervous system Hypothalamus NADPH dehydrogenase Ovarian hormone Vertebrata Mammalia Ventromedial nucleus Female Oxidoreductases Sex steroid hormone Brain (vertebrata)
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Summary:	The exact role of leptin in fasting has not been completely elucidated. To determine whether leptin can act in fasting to influence plasma estrogen levels and nitric oxide synthase reactivity in food regulating centers of the brain, we fasted female rats for 4 days and treated them i.p. with vehicle or 100 μg of recombinant mouse leptin as 1 ml on the 3rd and 4th day twice daily (10.00 and 17.00 h). Proestrus blood was collected at 10.00, 14.00, 18.00 and at 22.00 h, plasma obtained and assayed for estrogen (E2) and leptin levels. Verification of ovulation occurrence was by examining the oviduct for extruded ovum. The rat brains were removed and processed for nitric oxide synthase reactivity in the ventromedial hypothalamus (VMH) and arcuate nucleus (ARC) using NADPH-diaphorase histochemistry, a marker for neurons expressing NOS enzyme. Leptin effect on dependable variables such as food intake, water intake and body weight gain was also investigated. Four days fasting significantly decreased body weight, estrogen and postfast leptin levels, nitric oxide reactivity in the VMH and ARC nucleus and stopped ovulation in many (4 out of 5) rats fasted and given vehicle. Leptin treatment significantly increased plasma estrogen and postfast leptin levels, restored ovulation in many (4 out of 5) rats and increased nitric oxide reactivity in the VMH and ARC. Leptin significantly inhibited food intake, water intake and gain in body weight during recommenced feeding. These observations suggest that leptin could act in the pituitary–ovarian axis during fasting to improve reproductive function by partly stimulating estrogen secretion.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0006-8993 1872-6240
DOI:	10.1016/S0006-8993(00)02969-3