The participation of opioid peptides in forming the nonspecific protective reactions of the body

: The mechanisms of action of the opioid system on forming the nonspecific protective reactions of the body were investigated in rabbits and CBA mice injected the native preparation interleukin-1 (IL-1) of the rabbit after preinjection to the same animals with synthetic analog of leu-enkephalin--dalargin (D) or naloxone. Injection of D with IL-I to mice produced a 1.5 lower content of C-reactive protein (CRP) than in the control. Naloxone injected with saline or D prior to IL 1, prevented IL-1-induced rise in CRP level. The property of IL-1 was found to slow down process of summation of peripheral nociceptive impulses in the CNS of rabbits after i.v. injection the pyrogenic dose of IL-1. The preinjection of naloxone blocked these phenomenon and pyrogenic effect of IL-1 in the rabbits. The effects observed are supposed to result from the interaction of leukopeptides and opioid peptides at the level of cell receptors.