Increased insulin mediated glucose metabolism in fat cells from I versus C57BL mice.
The purpose of this study was to determine whether adipocytes from I strain mice, which are characterized by a greater in vivo glucose tolerance than most other strains, had a higher capacity to utilize glucose in response to physiological concentrations of insulin. Using C57BL mice as a control strain, we examined the effect of insulin on glucose metabolism in epididymal and inguinal adipocytes from 2-month-old male mice. Body weight was only slightly less (7%) for the I mice than for the C57BL mice, but fat pad sizes were 60 and 20% less for epididymal and inguinal depots, respectively, in the I mice. Fat cell size was also smaller in epididymal adipocytes from the I mice than from the C57BL mice. Fat cell size of inguinal adipocytes was similar in the two strains. Without insulin the rates of [U-14C]glucose incorporation into CO2 or lipids were twofold higher in cells from the I mice than in those from the C57BL mice. Maximal insulin concentration (2.5 nM) increased glucose metabolism by 140 and 500% in epididymal and inguinal adipose cells, respectively, in the I mice versus 30 and 50% in the C57BL mice. The maximal effect of insulin was reached at a much higher insulin concentration in the I mice than in the C57BL mice. The activity of fatty acid synthetase was four- to sixfold higher in fat cells from I than in those from C57BL mice. These results demonstrate an increased insulin responsiveness of glucose metabolism in fat cells from the I mice related to an increased lipogenic capacity. Furthermore, they show that adipose tissue in mice exhibits significant regional differences in terms of insulin responsiveness of glucose metabolism.
D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D064429:Fatty Acid Synthases / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains
D007328:Insulin; D064429:Fatty Acid Synthases; D005947:Glucose