Morphine reduces pulmonary inflammation in response to influenza infection

The present study shows that morphine reduces the pulmonary inflammatory re sponse to intranasal influenza virus infection in rats. Rats were infected with rat-adapted influenza virus (RAIV), which is a unique infectious agent because normal rats develop an acute pulmonary inflammatory response to RA IV and rapidly clear the virus within a few days with no mortality. Male Le wis rats were implanted with 75mg morphine pellets or placebo pellets 72 ho urs prior to intranasal RAIV infection. Rats were euthanized at 2, 24, 48, 72, and 96 hours after infection. Assessment of inflammation included accum ulation of inflammatory cells in the lungs, lung weight, and protein and LD H content of bronchial alveolar lavage fluid (BALF). Placebo-treated rats s howed a marked inflammatory response to RAIV infection, and morphine-treate d rats mounted less vigorous inflammatory responses to the infection. Taken together, these data suggest that morphine treatment impairs the inflammat ory response to RAIV infection in the lungs, which is consistent with prior work demonstrating that morphine is a potent anti-inflammatory agent in ot her areas of the body.