Role of opioid receptors in phagocytosis regulation and production of Th1/Th2 cytokines under acute cold stress in non-immune mice

Abstract

Endogenous opioid system plays an important role in the regulation of body functions under stress, providing stress-protective, analgesic and immunoregulatory effects. The aim of this work was to assess the effect of acute cold stress on the in vivo production of adaptive immunity cytokines IL-2, IL-4, IFNγ, phagocytosis, and production of reactive oxygen species in non-immunized mice with induced blockage of opioid receptors. The object of the study were male white mice subjected to acute cold stress at -20 °C for 10 or 60 minutes. To block opioid receptors, naloxone hydrochloride was used, which was administered subcutaneously at a dose of 0.2 mg/kg 20 min before inducing the stress. After the cold exposure, spleen and peritoneal lavage were obtained from the animals. The cytokine concentrations were determined using ELISA technique. The absorption activity of CD11+ cells of the peritoneal cavity was assessed using FITC-stained St.cohnii with a flow cytometer; the production of reactive oxygen species was assessed using the reaction of luminol-dependent chemiluminescence. It was found that the both cold stress regimens caused naloxone-independent inhibition of spontaneous IFNγ production. In stimulated cultures, an inhibitory effect on IFNγ secretion was registered in animals subjected to stress for only 60 min, being also independent on the opioid receptor blockade. IL-2 production decreased in stimulated cultures against the background of 60 min stress naloxone independently. Both variants of cold stress had no effect on IL-4 production. Stress for 60 min inhibited absorption activity of CD11+ cells from the peritoneal lavage and activated production of oxygen radicals, being, however, canceled by naloxone administration. Hence, acute cold stress led to naloxone-independent inhibition of Th1 cytokine production by splenocytes, naloxone-dependent inhibition of phagocytosis and activation of the microbicidal potential of peritoneal cavity cells.