The contribution of serotonin 1A receptors to kappa opioid immunosuppression.

Activation of kappa opioid receptors (kappa-OR) with the selective agonist rimorphin (0.1 mg/kg) produced marked suppression of the immune response in CBA mice. This effect was not seen on administration of rimorphin on the background of a reduction in the activity of the serotoninergic (5-HTergic) system resulting from stimulation of presynaptic (8-OH-DPAT, 0.1 mg/kg) or blockade of postsynaptic (WAY-100635, 1.0 mg/kg) 5-HT1A receptors. These data led to the conclusion that 5-HTergic mechanisms involving preand postsynaptic 5-HT1A receptors have a role in kappa-opioid-mediated immunosuppression.