TYPE-II IODOTHYRONINE 5'-DEIODINASE IN MOUSE BROWN ADIPOSE-TISSUE IS STIMULATED BY A SINGLE INJECTION OF ISOPROTERENOL IN AN OIL-WATER EMULSION

A single subcutaneous morning injection of the beta-adrenergic agonist isoproterenol (ISO) (10 mg/kg body weight) in an oil/water emulsion ( 70/30; v/v) caused a marked increase in the activity of the enzyme typ e II iodothyronine 5'-deiodinase (5'-D II) in the interscapular brown adipose tissue of BDF-1 mice. After a delay of 4 hours, the 5'-D II ac tivity began to rise in an almost linear fashion and was increased 3-f old after 8 hours, when compared to the control values. The results in dicate that this method of ISO administration may be a valid tool for artificial stimulation of brown adipose tissue in animals by beta-adre nergic agonists.