[Fat metabolism in growth-selected laboratory mice]

The object of the present study was to characterize the selection-conditioned differentiation of the biological performance of laboratory mice having been selected for 13 generations at the age of 6 weeks to body mass (Du-6) as well as simultaneously to body mass and high physical capacity (Du-6 + LB) by parameters of fat metabolism. The improved physical capacity with unchanged body composition (Du-6 + LB) coincides with increasing activity of dehydrogenases supplying NADPH (glucose-6-phosphate-dehydrogenase, 6-phosphate-gluconate-dehydrogenase, NADP-malate-dehydrogenase, NADP-isocitrate-dehydrogenase) in the liver. The doubling of the fat content of the body (Du-6) was accompanied by a significant increase of the G-6-PDH- and fatty-acid synthetase activity in the fatty tissue. Furthermore, the growth-selected animals showed an intensified transformation of 14C-glucose substrate in the lipids of the epididymal fatty tissues occurring especially at the selection age (42nd day) as well as at the earlier date of ontogenesis (32nd day). The insulin stimulation capacity of the fat cells as to the glucose incorporation, however, remained unchanged.