Attenuation of sensory preconditioning by noradrenaline depletion in the rat

In order to investigate the effect of noradrenaline (NA) depletion upon an associative learning phenomenon, sensory preconditioning, rats were inflicted with either 6-hydroxydopamine-induced lesions of the dorsal noradrenergic bundle (DNAB) or the locus coeruleus (LC), or with systemic injections of the NA neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4). Using appropriate controls (the UP groups) sensory preconditioning was demonstrated clearly in the non-lesion conditions (Sham or saline), but was blocked or strongly attenuated in the DNAB and DSP4 conditions. LC lesions did not affect sensory preconditioning. These findings suggest that the loss of central NA may cause some disruption of some aspects of complex associative learning. The role of NA in sensory preconditioning may be relevant to current notions of NA function.