Chronic cold stress modulates the function of peritoneal macrophages in vivo.

On day 7 of chronic cold stress, concentration of corticosterone in plasma was established to increase, zymosan-induced production of reactive oxygen species was activated, and IL-10 synthesis by macrophages was enhanced regardless of the opiate receptor blockade. Increase in the concentration of corticosterone was independent of the blockade of opioid receptors, whereas the zymosan-induced increase in the production of oxygen radicals and activation of the spontaneous production of IL-10 was blocked in mice by naloxone. Chronic cold stress had no effect on the production of IL-1β and TNF-α.