The effect of capsaïcin on temperature regulation of the rat.

1. Subcutaneous injection of capsaïcin (6-11 mg, or 21-66 mg cumulative), permanently reduced the capacity of rats to withstand a hot environment, as described by Jancsó-Gábor et al. (1970). 2. The treated rats thermoregulatory behaviour was not different from that of control rats, both in hot and cold environments. 3. Saliva secretion was decreased in a hot environment, and the weight of the submaxillary glands was reduced in capsaïcinized rats. 4. It is concluded that hyperthermia present in treated rats when subjected to a warm environment is not due to a disruption of sensu stricto temperature regulation, but rather to a decreased salivary secretion. Whether this decrease has a central or a peripheral origin is not known.