The effects of a reversible colchicine-induced lesion of the anterior ventral region of the third cerebral ventricle in rats.

Colchicine was injected into the region of the organum vasculosum lamina terminalis/anterior region of the third cerebral ventricle (OVLT/AV3V) to produce a temporary disruption of the nervous connections of this area and the rest of the anterior hypothalamus, but to maintain the vascular connections intact. Rats were kept in metabolism cages throughout the experiment and food and water intake plus urine and electrolyte excretion and body weight were measured each day. Food intake, body weight gain and urine and sodium excretion were reduced for several days after the injection of colchicine and the rats went into a marked positive sodium balance from the third day postinjection. Following 24 h water deprivation, 7 days after the colchicine injection, water intake was increased for 2 days. Urine and electrolyte excretion and food intake were also increased on the second day after the deprivation. Following a second deprivation, 10 days later, the colchicine-injected animals behaved as the control rats had done during both the deprivation periods. Injections of colchicine into the OVLT region of the AV3V, that would have blocked neural activity while maintaining a constant blood supply, produced some of the characteristics of a 'normal' lesion in this area; the rats decreased sodium excretion and increased their water intake in response to water deprivation. Therefore, colchicine may provide a useful means of investigating what role the constituent areas of the AV3V play in body fluid regulation.