Beta-adrenoceptor antagonists may attenuate hyponeophagia in the rat through a serotonergic mechanism

The unconditioned inhibition of feeding in a novel setting (hyponeophagia) was reduced by propranolol and another potentially centrally acting beta-adrenoceptor antagonist, pindolol but not by a peripherally acting one, atenolol. A similar attenuation of hyponeophagia was seen following the 5-HT antagonist methysergide but no consistent effects were observed following some dopamine antagonist drugs. 5-Methoxy N,N-dimethyltryptamine (5-MeODMT), a compound with central 5-HT agonist properties, consistently potentiated hyponeophagia, an effect which was reversed by the centrally acting beta-adrenoceptor antagonists and by methysergide. The results are interpreted as evidence for a 5-HT mediation of hyponeophagia and for a probable central 5-HT antagonist role for propranolol and pindolol.