Feeding and body weight regulation after 6-OHDA application into the preoptic area

Our previous results showed that neurochemical destruction of the amygdaloid terminal field of the mesolimbic dopaminergic system caused disturbances in body weight regulation and feeding. In the present experiments, it was studied whether 6-hydroxydopamine (6-OHDA)-induced bilateral lesions of the mesolimbic dopaminergic system in the lateral preoptic area produce similar symptoms in rats. To enhance the selectivity of the neurotoxin, 6-OHDA was also used after desmethylimipramine (DMI) premedication. Both 6-OHDA and 6-OHDA + DMI treatments resulted in hypophagia, hypodipsia and body weight decrease. A significant increase of water intake was found in sham-operated controls and lesioned animals, in response to extracellular dehydration caused by polyethylene glycol. Intracellular dehydration induced by hypertonic saline resulted in increase of water intake of all animals; however, 6-OHDA- and 6-OHDA + DMI-treated rats drank less than the controls. Similar observation has been made when food intakes were compared after 2-deoxy-D-glucose treatment. Results show that mesolimbic dopaminergic elements play an essential role in the regulation of feeding.