Journal of Animal Science, Vol 76, Issue 4 1012-1018, Copyright © 1998 by American Society of Animal Science

JOURNAL ARTICLE

Effect of clenbuterol on endocrine status and nitrogen and energy balance in food-restricted rats

L. A. Cardoso and M. J. Stock
Instituto de Investigacao Cientifica Tropical, Centro Interdisciplinar de Investigacao em Sanidade Animal, Faculdade de Medicina Veterinaria, Lisboa, Portugal.

We administered clenbuterol as a dietary admixture (4 mg/kg diet) to three groups of male Wistar rats (n = 8) housed individually in metabolism cages and fed for 15 d at 110, 160, and 235% (ad libitum) of the estimated requirement for energy maintenance. Untreated groups at each level of energy intake and a baseline group were also included. In the diet-restricted rats, clenbuterol induced greater and more persistent increases in nitrogen balance, biological value, and net protein utilization than it did in the ad libitum-fed rats. Energy balance was increased by clenbuterol treatment in the diet-restricted rats, with no significant changes occurring in the ad libitum fed rats. Compared with untreated rats, clenbuterol reduced blood glucose in all diet groups and serum insulin in the ad libitum and the moderately restricted (160%) rats. Serum IGF-I was increased in the highly restricted (110%) rats. Corticosterone levels were increased by clenbuterol treatment in all diet groups. These results are consistent with previous results showing that clenbuterol can help improve growth, but they also show that clenbuterol can offset the effects of food restriction on protein and energy metabolism.