Macrophages (Mf) are a versatile group of phagocytic cells responsible for fulfilling a variety of immune functions, most notably for mounting the initial anti-microbial response and for the clearance of cellular debris and apoptotic bodies. The key processes for fulfilling these functions include the production of reactive oxygen intermediates (ROIs) and nitric oxide (NO). Mf also express a variety of receptors, including opioid, serotonin, and norepinephrine receptors, and thus can react to various substances. Our study aimed to examine the effects of oxycodone and buprenorphine on the production ROIs and NO by Mf from intraperitoneally-treated mice, as compared to the previously studied morphine, fentanyl, and methadone, as well as the effects of the analgesic adjuvants gabapentin, amitriptyline, and venlafaxine. ROIs was estimated via luminol and lucigenin dependent chemiluminescence assay, and NO secretion was estimated via a colorimetric method utilizing a modified Griess reaction. We observed an overall decrease in both ROIs and NO production by Mf from adjuvant-treated mice, especially with amitriptyline. Opioids, however, resulted in enhanced ROIs production and mixed NO secretion, with oxycodone and buprenorphine have the least immunomodulatory effects. As ROIs and NO are potent mediators of Mf activity during the innate immune response, our current results express great translational potential. Our results suggest that OPs administration may boost Mf anti-microbial response. On the other hand, during sterile in ammation, enhanced generation of ROIs by Mf influenced by opioids may increase the risk of tissue damage, but co-administration of adjuvants could abolish this adverse effect.
Keywords: amitriptyline; gabapentin; innate immunity; nitric oxide; opioid; pain; reactive oxygen intermediates; venlafaxine.