The effects of 6-hydroxydopamine lesions of the nucleus accumbens and caudate nucleus of rats on feeding in a novel environment.

Open field activity and feeding behavior were studied in separate groups of rats 1 or 6 weeks after infusions of the neurotoxin, 6-hydroxydopamine (6-OHDA) into the nucleus accumbens or caudate nucleus. These infusions resulted in a specific destruction of the catecholamine innervation of the injected area. When compared with rats which received infusions of vehicle alone, both lesions resulted in a relative reduction in locomotor activity 1 week, but not 6 weeks, after the operation. Both lesions also resulted in a more rapid onset of feeding from wire baskets containing familiar laboratory chow. Rats with lesions of the nucleus accumbens also fed for longer, consumed more food, and fed in longer bouts than did sham-lesioned animals, but rats with lesions of the caudate nucleus did not. These data show changes in feeding behaviour produced by 6-OHDA infusions into the dopamine terminal fields which were long lasting in comparison with the locomotor impairments, and did not arise as a result of locomotor impairment. The differences in feeding behaviour may result from more general changes in behaviour such as an impairment in the reactivity to novel environmental stimuli or switching between types of behaviour.