Upregulation of uncoupling protein homologues in skeletal muscle but not adipose tissue in posttraumatic insulin resistance

Metabolic alterations after surgical stress include peripheral insulin resi stance and increased utilization of fat as a fuel substrate. An up-regulati on of skeletal muscle uncoupling proteins (UCPs) has been associated with p hysiologic states of insulin resistance and enhanced fat metabolism in rode nts. We examined whether posttraumatic insulin resistance induced the UCPs in gastrocnemius and soleus muscle and white adipose tissue in an experimen tal model of surgical trauma. Insulin sensitivity was significantly reduced in isolated soleus muscles but unchanged in adipocytes after trauma. In tr aumatized rats, mRNA and protein contents of UCP2 and UCP3 and were signifi cantly increased in both muscle types. UCP2 protein content in adipose tiss ue was unaltered by surgical stress, Circulating NEFAs and glycerol were re duced after surgical trauma, We hypothesize that the changes in UCP2 and UC P3 gene and protein expression are involved in the regulation of substrate utilization in posttraumatic insulin resistance. (C) 2001 Academic Press.