Hepatic myc protooncogene expression is reduced and possibly correlated with body temperature in fasted Peromyscus leucopus mice
- 21 Downloads
To examine the effect of fasting on c-myc protooncogene expression, the level of c-myc mRNA was determined at 6 circadian stages (4 hr intervals for 24 hr) in the livers of Peromyscus leucopus mice. After 3 days of fasting a reduced level of c-myc expression was observed compared with ad libitum fed controls (24-hr mean relative expression values = 0.73 and 1.16, respectively, p<.001). Core body temperature, which was continuously monitored using a thermister/transmitter system, showed a significantly lower mean value in the fasted animals (33.1°C vs 36.4°C after 3 days, p<.001). In addition, for both ad libitum fed and fasted mice, expression of c-myc and temperature showed significantly different values at various circadian stages indicating that both parameters exhibited biological rhythms. These findings are qualitatively similar to our previous results with long-term dietary restricted animals (60% of ad libitum for over 100 weeks), indicating that manipulation of the dietary regimen can affect the level of protooncogene expression. Furthermore, the results showed a high degree of correlation between c-myc expression and core body temperature in fasted animals in a manner which suggests that alterations in body temperature precede and may signal subsequent changes in c-myc expression.
KeywordsBody Temperature Core Body Temperature Dietary Regimen Biological Rhythm Fast Animal
Unable to display preview. Download preview PDF.
- 1.McCay, C.M.w, Crowell, M.F., and Maynard, L.A.: The effect of retarded growth upon the length of life span and upon ultimate body size. J. Nutr., 10: 63–79, 1935.Google Scholar
- 5.Sarkar, N.H., Fernandez, G., Telag, N.T., Koorides, I.A., and Good, R.A.: Low-calorie diet prevents the development of mammary tumors in C3H mice and reduces circulating prolactin levels, murine mammary tumor virus expression, and proliferation of mammary alveolar cells. Proc. Natl. Acad. Sci. U.S.A., 79: 7758–7762, 1982.PubMedGoogle Scholar
- 7.Ruggeri, B.A., Klurfeld, D.M., and Kritchevsky, D.: Biochemical alterations in 7, 12-dimethyl-benz[a]anthracene-induced mammary tumors from rats subjected to caloric restriction. Biochem. Biophys. Acta, 939: 239–249, 1987.Google Scholar
- 10.Sacher, G.: Life table modification and life prolongation. In Handbook of the Biology of Aging. Finch, C. and Hayflick, L. (eds.), Van Nostrand Reinhold, New York, 1977.Google Scholar
- 21.Duffy, P.H., Feuers, R.J., and Hart, R.W.: Effect of age and torpor on the circadian rhythms of body temperature, activity and body weight in the mouse (Peromyscus leucopus). In: Pauly, J. and Scheving, L. (eds.), Advances in Chronobiology, Part B, Alan R. Liss, Inc., New York, 1987, pp. 111–120.Google Scholar