Decrease in adipose S-100 protein levels by epinephrine in rat.

Soluble S-100 protein levels in epididymal adipose tissue of male rats (1.3 +/- 0.1 micrograms/mg protein) were markedly decreased (to 0.15 +/- 0.06 microgram/mg protein) by serial injection of epinephrine (0.1 mg/day for 9 days). But injection of insulin in a similar manner (4 U/day for 9 days) had little effect on the adipose S-100 protein levels (1.1 +/- 0.2 micrograms/mg protein). The S-100 protein levels in cerebrum, spleen, and adrenal gland were not affected by epinephrine or insulin administration. These results strongly suggested that S-100 protein levels in adipose tissue are regulated hormonally.