MORTALITY, GROWTH AND LIVER GLYCOGEN IN YOUNG MICE EXPOSED TO COLD

¹ Department of Zoology, Glasgow University

Mice of four strains were reared at 21°C. and then transferred to -3°C., in individual cages with nesting material. Controls were kept in similar conditions at 21°C. Many of the mice of two A strains died when stressed by cold at the age of 3 weeks, but none at 5 or 12 weeks. Many C57BL and GFF mice died when stressed at 5 weeks. Death usually occurred during the first 3 days, often on the first day. All stressed mice lost weight, especially in the first 2 days; if they survived, they made up the lost weight but they grew more slowly than the controls at all stages.

Mice reared at -3°C. and stressed in that temperature when 3 weeks old had a lower mortality than those transferred from 21°C., and survivors did not lose weight. Mice reared at -3°C. and transferred to 21°C. at 3 weeks, although initially lighter, grew quickly and after 1 week were as heavy as the controls.

Three-week-old mice stressed at -3°C. lost liver glycogen quickly whether they had been reared at 21°C. or -3°C. This was not due to a failure to eat, and there was no evidence that death resulted from inability to mobilize carbohydrate reserves.

Note:

We are grateful to the Nuffield Foundation and the Medical Research Council for grants which made this research possible. Dr. H. N. Munro kindly advised us on the method of estimating glycogen.