Excessive zinc in diet induces leptin resistance in Wistar rat through increased uptake of nutrients at intestinal level.
METHODS
The ob gene has either been found to be mutant defective resulting in a deficiency of its product leptin or leptin has been found to be resistant to its receptors in obese human and rodents. The factors inducing leptin resistance have not been identified. Since excessive bioavailability of Zn has been implicated in obesity, we investigated if its excess in diet induces leptin resistance.


METHODS
For the investigations, three groups of Wistar rats were included in this study and they were fed on equicalories semi synthetic basal diet containing 20 mg, 40 mg or 80 mg Zn/kg diet for 120 days. There after they were sacrificed for hormonal status and intestinal investigations.


RESULTS
The data of this study revealed that the food intake, gain in body weight, serum leptin, glucose, insulin, cortisol increased with increased Zn concentration in diet. TEM study showed a positive correlation between Zn concentration in diet and number of microvilli/unit surface area of the mucosal epithelial cells of the intestine.


CONCLUSIONS
The results of this study suggest that excessive bioavailability of Zn induces leptin resistance through increased uptake of nutrients at intestinal level, leading to the growth of the fat cells which aggravated the leptin synthesis and its release in the blood stream. In spite of its higher circulating level, it was unable to reduce the food intake and gain in body weight in Zn treated rats equivalent to the control group.
Department of Zoology, Panjab University, Chandigarh, India. sktaneja@gmail.com
Satish Kumar
SK
Taneja
Mridula
M
Jain
Reshu
R
Mandal
Kirti
K
Megha
D000818:Animals; D019587:Dietary Supplements / Q000009:adverse effects*; D004435:Eating / Q000187:drug effects*; D007408:Intestinal Absorption / Q000187:drug effects*; D020738:Leptin / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015032:Zinc / Q000627:therapeutic use*
D020738:Leptin; D015032:Zinc