Melatonin and estradiol effects on food intake, body weight, and leptin in ovariectomized rats.
OBJECTIVE
The study in ovariectomized (Ovx) rats, as a model of menopausal status, of the effects of melatonin (M) and/or estradiol (E), associated or not with food restriction, on body weight (BW) and serum leptin levels.


METHODS
Female SD rats (200-250 g) were Ovx and treated with E, M, E+M or its diluents. Control sham-Ovx rats were treated with E-M diluents. After 7 weeks being fed ad libitum, the animals were exposed for 7 more weeks to a 30% food restriction. We measured: food intake, BW, nocturnal and diurnal urinary excretion of sulphatoxymelatonin (aMT6s), leptin in midday and midnight blood samples, glucose, total cholesterol, LDL, HDL and triglycerides.


RESULTS
Day/night rhythm of aMT6s excretion was preserved in all cases. The increase of aMT6s excretion in M-treated animals basically affected the nocturnal period. In animals fed ad libitum, E fully prevented Ovx-induced increase of BW, leptin and cholesterol. Melatonin reduced food intake and partially prevented the increase of BW and cholesterol, without changing leptin levels. Under food restriction, M was the most effective treatment in reducing BW and cholesterol. Leptin levels were similar in M, E or E+M treated rats, and lower than in untreated Ovx rats.


CONCLUSIONS
Our result gives a preliminary experimental basis for a post-menopausal co-treatment with estradiol and melatonin. It could combine the effectiveness of estradiol (not modified by melatonin) with the positive effects of melatonin (improvement of sleep quality, prevention of breast cancer, etc.). The possible beneficial effects of melatonin which could justify its use, need to be demonstrated in clinical trials.
Sanchez-Mateos
S
S
Department of Physiology and Pharmacology, School of Medicine, University of Cantabria, 39011 Santander, Spain.
Alonso-Gonzalez
C
C
Gonzalez
A
A
Martinez-Campa
C M
CM
Mediavilla
M D
MD
Cos
S
S
Sanchez-Barcelo
E J
EJ
D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D002784:Cholesterol / Q000097:blood; D004195:Disease Models, Animal; D004435:Eating / Q000187:drug effects*; D045166:Estradiol Congeners / Q000494:pharmacology*; D005260:Female; D020738:Leptin / Q000097:blood*; D008550:Melatonin / Q000494:pharmacology*; D009765:Obesity / Q000378:metabolism; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D045166:Estradiol Congeners; D020738:Leptin; D002784:Cholesterol; D008550:Melatonin