Impaired escape reaction from noxious and nonnoxious heat in rats treated with the selective noradrenergic neurotoxin DSP-4.

The escape reaction, as an indicator of behavioral thermoregulation, was studied in rats pretreated with the selective noradrenergic neurotoxin DSP-4. The animals were kept for 30 min in a heated floor (42, 44, 46, 48 and 50 degrees C) cage containing a wooden platform placed at a height of 12 cm, which enabled the rats to escape from the warm floor. The latency of escape and the time spent on the platform were recorded. The performance of DSP-4-treated rats was significantly inferior to that of the control rats at all tested temperatures. These findings indicate a general function of the central noradrenergic neurons in defense alarm reactions, including a significant role in heat defense behavior.