Steroid and beta adrenergic receptor modifications in target organs of broiler chickens fed with a diet conteining beta 2 – adrenergic agents

The illegal use of b2-agonists as repartitioning agents to improve production performance and carcass composition can induce changes in various organs of exposed animals. The aim of the present study was to evaluate the effects induced by dietary b-agonists on b-AR, AnR and GR in male broiler target organs. Fifty-four male broiler chickens (Ross 508), 26 days old, were randomly divided into three homogeneous experimental groups and fed for 21 days with a standard diet containing placebo (group 1, control), 1 ppm of clenbuterol (group 2) and 1 ppm of cimaterol (group 3). Tissue samples of heart, lung, brain, testicle, spleen, thymus and Bursa of Fabricius were collected post-mortem then cytosol fractions were used for AnR (testicles) and GR (spleen, thymus and Bursa of Fabricius), and membrane fractions for b-AR (all tissues but testicles) determination by binding assays. The dietary administration of b-adrenergic agents as repartitioning agents induced a significant decrease in AnR concentration in the testicle, in GR levels in the lymphoid tissues and in b-AR concentrations of different target organs of male chickens. Present data confirm those observed in female chickens and suggest that in poultry the regulation exerted by adrenergic stimulation on steroid receptor concentrations produces different effects than in mammals.