Caloric restriction and 7,12-dimethylbenz(a)anthracene-induced mammary tumor growth in rats: alterations in circulating insulin, insulin-like growth factors I and II, and epidermal growth factor.

摘要: Caloric restriction (CR) inhibits many neoplastic diseases in rodents, yet the biochemical mechanism(s) for these effects are poorly understood. We have examined of ad libitum (AL) feeding with 25 or 40% CR on promotion 7,12-dimethylbenz( a )anthracene-induced mammary tumorigenesis virgin female Sprague-Dawley rats. Further, we also studied influence chronic temporal alterations circulating insulin, insulin-like growth factor I/somatomedin C, II/multiplication-stimulating activity, and epidermal levels at 0, 1, 3, 5, 11, 20 weeks carcinogen- vehicle-treated animals. Tumor incidence multiplicity were markedly inhibited ( P < 0.05) increasing CR. Fasting serum C exhibited significant acute decline 1 3 weeks, but comparable to AL-fed controls throughout remainder 5-month study, despite continued differences weight gain between AL Levels activity no discernible pattern relation Serum insulin showed age-dependent increases, affected by all time points. Insulin significantly reduced rats from onward compared controls, while 25% resulted nonsignificant 0.07) reductions study. No observed )anthracene- Circulating was not detectable any treatment group regardless nature duration dietary regimen, blood collection, subsequent tumor-bearing status. These data suggest that decreased their complex interactions vivo may play role inhibition tumor