Effect of Stress on the Production of Antibodies and IL-2, IL-4, and IFNγ Depending on the Time of Antigen Administration and Evaluation of the Role of Opioid Receptors

The time of stress exposure relative to the moment of immunization affects the direction of the immunoregulatory effect of stress. In case of stress exposure preceding immunization, rotation stress stimulated the production of antibodies, while immobilization depressed it. After antigen injection, these types of stress had no significant effect on the formation of antibody-producing cells. Acute cold stress did not affect the number of antibody-forming cells before immunization, but stimulated the humoral response after it. At the same time, the effect of stress on the production of antibodies was leveled by blockade of opioid receptors with naloxone for rotation and immobilization, but was not canceled for acute cold stress. A similar pattern was revealed when analyzing the effect of stress exposure on cytokine production. Cold stress before antigen administration to mice had almost no effect on the production of IL-2, IL-4, IFNγ, while rotational and immobilization stress naloxone-dependently modulated the synthesis of IL-2 and IL-4. On the contrary, in animals subjected to stress after antigen administration, only cold stress significantly modulated the production of IL-2 and IL-4.

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.

[INFLUENCE OF COLD STRESS ON FUNCTIONAL ACTIVITY OF MOUSE PERITONEAL MACROPHAGES UNDER OPIATE RECEPTORS BLOCKADE]

The effect of 10- and 60-min cold stress was analyzed on reactive oxygen species (ROS) formation, peritoneal macrophage production of cytokines and corticosterone level under the opiate receptor blockade. It was observed that mice exposed to -20 °C for 10 min demonstrated the ROS inhibition, the effect was leveled against the background of naloxone introduction. The animal group subjected to 60-min stress on the contrary, showed the naloxone-dependent promotion of ROS product. Both variants of cold stress did not render significant effect on IL-1ß production. Against 60-min cold stress the TNF-α production was naloxone-dependently stimulated both in spontaneous and zymosan-induced cultures. IL-10 production by macrophages was improved irrespective of the cold stress duration, as well as stimulation presence or absence; and was abolished against a background of opiate receptor blockade. Therefore, the directionality of acute cold stress on the macrophage functions was dependent both on the parameters'' analyzed and on the duration of the exposure while the opiate receptor blockade significantly modified the immunoregulatory effects of hypothermia.

[Effect of opioid receptor blockade on antibody response and proliferative response under stress conditions]

It is established that rotation and immobilization stress produces bidirectional effect on AFC number in spleen and on proliferative response of splenocytes. The rotation stress results in augmentation of AFC formation and promotion of spontaneous proliferative activity of splenocytes. The micro-opioid receptor blockade with naloxone, but not delta-receptor blockade with naltrindole, abolished the effects of rotation. In contrast, the immobilization stress caused the suppression of the parameters of humoral immune response and lowered spontaneous and induced proliferative activity of splenocytes. The opioid receptor blockade with naloxone was found to level the suppressive effects of immobilization, while naltrindole exhibited a less pronounced effect. Both variants of stress demonstrated the involvement of opioid system in regulation of AFC number during induction of the immune response.