Hn. Bhargava et al., EFFECTS OF NALTREXONE ON MORPHINE-INDUCED TOLERANCE AND PHYSICAL-DEPENDENCE AND CHANGES IN CELLULAR IMMUNE FUNCTION IN MICE, Brain research, 690(1), 1995, pp. 121-126
The effects of naltrexone on tolerance/dependence, as well as alterati
ons in cellular immune function induced by morphine administration, we
re determined. Mice were rendered tolerant to and physically dependent
on morphine by subcutaneous implantation of pellets containing 75 mg
of morphine. Implantation of naltrexone pellets (10 mg) blocked the de
velopment of tolerance to the analgesic action of morphine, as well as
the development of physical dependence. Morphine suppressed lymphoid
organ weights and cellularities, and this suppression was blocked by n
altrexone. B-Cell proliferation was suppressed in morphine-tolerant bu
t not in morphine-abstinent mice, and this suppression was exacerbated
by naltrexone. Morphine tolerance and abstinence were associated with
suppression of IL-2 production, which was completely blocked by naltr
exone. NK cell activity was not significantly affected by either morph
ine or naltrexone exposure. The results suggest that the effects of mo
rphine on the immune system are at least partially mediated through op
ioid receptors.