Human recombinant interferon alpha inhibits naloxone binding to rat brain membranes

Abstract Regulation of certain central nervous system (CNS) functions by the immune system may involve interferons (IFNs) acting through opioid receptors. Human recombinant interferon alpha (hrIFNα), as well as natural IFNα, have been reported to modulate a variety of physiological CNS functions both in vivo and in vitro . If the mechanism is via opioid receptors then IFNα should inhibit the binding of certain opioid radioligands to brain membranes. This study reports the inhibitory effect of hrIFNα on the binding of 3 H-naloxone to rat brain membranes in vitro . The inhibitory effect at 37°C is hrIFNα concentration dependent over the range of 500 to 6000 antiviral units per ml (U/ml) with 500 μg of membrane protein. The presence of NaCl (100mM) increases specific binding of naloxone and attenuates the inhibitory effect of hrIFNα. The inhibitory effect of hrIFNα is sensitive to temperature with maximum inhibition observed at 37°C, and less as incubation temperature is reduced. These data suggest that IFNα may modulate certain physiologic functions via opioid pathways in the brain.