Modulation of the innate immune response to HSV-1 following acute administration of morphine: role of hypothalamo-pituitary-adrenal axis

A single injection of morphine significantly increased interferon (IFN)-β and IFN-α mRNA in spleens from herpes simplex virus (HSV)-1 infected male Balb/cByJ mice. However, significant suppression of IFN-γ and interleukin (IL)-12 production was observed in spleens from morphine-treated mice. Pretreatment with RU486 blocked morphine-induced increases in IFN-β, and reversed the suppression of IFN-γ. However, RU486 did not restore IFN-α or IL-12. The results suggest that a single exposure to morphine 4 h prior to infection can significantly alter innate immune responses to a viral pathogen, and that these effects are partially mediated by glucocorticoids.