Apomorphine and oxotremorine hypothermia in the pigeon: dopaminergic-cholinergic interaction and the effect of paleostriatal lesions.

The role of central dopaminergic and cholinergic systems and their interaction in avian temperature regulation was studied. Pigeons were injected with apomorphine intrahypothalamically and apomorphine and oxotremorine intramuscularly (i.m.) at 20 degrees C. The injections caused suppression of shivering, a decline in body temperature, and with the i.m. injections most frequently a transient increase in foot temperature. Pretreatment with atropine (i.m.) did not affect hypothermia induced by i.m. apomorphine. Bilateral electrolytic lesions placed in the dopamine and acetylcholinesterase-rich brain region (paleostriatum augmentatum) did not attenuate the responses to i.m. apomorphine and oxotremorine. These results suggest that medial aspects of paleostriatum augmentatum in the pigeon do not contribute to hypothermia induced by dopaminergic and cholinergic stimulation of the brain. They also indicate that no cholinergic link is involved in mechanisms mediating the hypothermic effects of i.m. apomorphine.