Behaviorally conditioned immunosuppression in the rat is regulated via noradrenaline and β-adrenoceptors.

Abstract Using Cyclosporin A (CsA) as an unconditioned stimulus has previously demonstrated that behaviorally conditioned inhibition of splenocyte proliferation and cytokine production is mediated via the splenic nerve. Therefore, we currently examined the adrenergic modulation of conditioned suppression of splenocyte function. Chemical sympathectomy via 6-OHDA completely blocked the conditioned suppression of splenocyte proliferation to mitogens and cytokine (IL-2, IFN-γ) production. Furthermore, administration of β-adrenoceptor antagonist propranolol abrogated the conditioned effect on splenocyte proliferation. Supporting the position that conditioning is β-adrenergic-dependent, addition of β-adrenoceptor agonist, but not α-adrenoceptor agonists, to splenocytes in vitro mimicked the conditioned suppression of splenocyte functions, with these effects blocked by propranolol. Therefore, these data indicate that behavioral conditioning of splenocyte function in the rat is regulated by the sympathetic nervous system, predominantly via β-adrenergic mechanisms.