BEHAVIORAL AND ELECTRO-PHYSIOLOGICAL CHANGES FOLLOWING MICRO-INJECTIONS OF COLCHICINE INTO THE SUBSTANTIA NIGRA

Male Sprague-Dawley rats received bilateral microinjections of colchicine (2 or 4 μg in 1 μl) into the substantia nigra. During the first 2 days the animals were hyperactive, intense gnawing and chewing were observed, and food intake was significantly increased. During the next 3 or 4 days, activity, food and water intakes and body weight gain were markedly reduced; the behavior was similar to that previously observed following damage to the substantia nigra and nigrostriatal pathway from 6-hydroxydopamine or electrolytic lesions. This period of hypophagia and hypodipsia was followed by a rebound increase in food and water intake for several days until body weight returned to normal levels. Field potentials recorded from the caudate nucleus in response to electrical stimulation of the substantia nigra were reduced in amplitude during the first 4 days following microinjections of colchicine into the substantia nigra and recovered by Day 7. These reversible behavioral effects of microinjections of colchicine into the substantia nigra confirm the importance of the nigrostriatal pathway in motor and ingestive behaviors. © 1979.