Expression of Fos during sham sucrose intake in rats with central gustatory lesions

摘要

sucrose is normally rewarding to rats and many other animals. The neural bases for this hedonic effect are not understood, but, at some point, the afferent neural activity must engage central reward systems. Sucrose ingestion releases dopamine (DA) in the nucleus accumbens (16). This DA release is concentration dependent but is independent of the volume consumed or the nutritional consequences of the ingestion (19). For these and other reasons, accumbens DA release can be taken as a central index of the reward value of the gustatory stimulus (40). From this, it follows that understanding how gustatory afferent activity reaches forebrain reward systems will aid in detecting the neural underpinnings of hedonic value.In the rat, the central gustatory system bifurcates in the pons mto a dorsal, thalamocortical projection and a ventral, hmbic distribution (30). Lesions of the thalamic taste relay have no effecton accumbens DA release during sucrose licking. The same DA response is substantially blocked, however, when the lesions are in the pontine parabrachial nuclei (PBN), the second central gustatory relay (18). This implies that the limbic gustatory projection originating in the PBN supports this DA index of reward but that the thalamocortical taste system contributes little if anything to the process.