Opposed behavioral syndromes in rats with partial and more complete central serotonergic lesions made with 5,6 dihydroxytryptamine.

Rats with central 5HT lesions made with multiple small injections of 5,6 dihydroxytryptamine (6×10 Μg 5,6 DHT) rear more but locomote less than Controls in novel environments, are more reactive to visual stimulation, and consume small, frequent meals. A converse behavioral syndrome is observed in rats in which smaller lesions are made (3×10 Μg 5,6 DHT) and a longer recovery period allowed. These latter animals show increased locomotion and decreased rearing in novel environments, consume large, infrequent meals, and demonstrate an exaggerated responsivity to the analgesic properties of morphine. It is proposed that the behavioral syndrome of rats with partially damaged, supersensitive circuity may clarify some paradoxical aspects of chronic 5HT disruptions. [ABSTRACT FROM AUTHOR]