Direct stimulation of the adrenal cortex by interleukin-1

The impact of human recombinant beta-interleukin-1 (IL-1) on adrenocortical stimulation was investigated. This study asked three questions: Does IL-1 increase the corticosterone levels of rat serum? Is there a direct effect on the adrenal cortex? What is the mechanism of this effect? The intraperitoneal injection of IL-1 (70 micrograms) in anesthetized male Fisher rats resulted in elevated corticosterone levels at 30 minutes and reached a maximum at 180 minutes (94 +/- 12 versus 34 +/- 4 micrograms/dl, p less than 0.01). Next, the adrenal glands from separate animals were perfused in situ. Corticosterone secretion was significantly increased (p less than 0.01) 90 minutes after a single arterial bolus of 35 micrograms of IL-1. The response to IL-1 was dose dependent, beginning at 3.5 micrograms and reaching a maximum at 35 micrograms. The addition of indomethacin (3 mumol/L) completely abolished the stimulatory effect of IL-1. This study demonstrates that IL-1 increases rat serum corticosterone levels, IL-1 directly stimulates the adrenal cortex, and the stimulation may be mediated through prostaglandin synthesis. This is the first evidence that IL-1 has a direct stimulatory effect on the adrenal cortex.