RAT ADIPOSE OB MESSENGER-RNA LEVELS IN STATES OF ALTERED CIRCULATING GLUCOSE AND INSULIN

We measured levels of ob mRNA in epididymal fat pads of rats exposed t o manipulations designed to alter circulating insulin and glycemia. Ch anges in ob mRNA were compared to alterations in GLUT-4 glucose transp orter mRNA, which is known to be regulated under these conditions. 48 h fasting decreased GLUT-4 mRNA to 23% of control with restoration beg inning by 6 h refeeding and full restoration at 24 h. In contrast, ob mRNA decreased less markedly to 47% of control with only partial resto ration by 24 h. Two days of streptozocin (STZ)-diabetes (glucose > 400 mg/100 ml) decreased GLUT-4 mRNA to 8% of control with restoration by two days of S.C. insulin. In contrast, ob mRNA decreased to 42% of co ntrol and was not restored by insulin. Six days of insulin administrat ion to normal rats under conditions of ad lib. feeding, but without ot herwise preventing the blood glucose from decreasing, resulted in no s ignificant change in levels of either ob or GLUT-4 mRNA. (C) 1996 Acad emic Press, Inc.