Effects of Thyroxine,Epinephrine and Cold Exposure on Lipolysis in Genetically Obese (ob/ob) Mice 1

Abstract

Summary

Treatment of ob/ob mice with T₄ 24 hr prior to cold exposure did not alter plasma concentrations of glucose, insulin and FFA during cold exposure although ob/ob mice remained hyperglycemic and hyperin-sulinemic when compared to nonobese mice. FFA content of and FFA release from isolated adipocytes were significantly elevated in T₄ -treated obese mice after cold stress as compared to untreated obese mice. T₄ treatment also produced a marked increase in epinephrine-stimulated FFA release from fat cells of obese mice in vitro.

These results indicate that correction of the hypothyroid status of ob/ob mice with pharmacological doses of T₄ improved the in vitro lipolytic response of fat cells, but did not alter the circulating concentrations of important energy sources for thermogenesis in vivo.

The technical assistance of Ms. Teresa Pasquine is gratefully acknowledged.