Body and brain temperatures increase when Sprague-Dawley rats explore the external environment, and brown adipose tissue (BAT) thermogenesis contributes to the temperature increases (Ootsuka et al., 2009, Blessing et al., 2012). We have now assessed whether a salient novel environmental event activates BAT thermogenesis. Under inhaled isoflurane (2% in oxygen) anaesthesia, 5 male Sprague-Dawley rats (300-450 g) were instrumented with chronically implanted thermistors to measure BAT and body temperature (Blessing et al., 2012). All surgical procedures were performed in accord with the Animal Welfare Ethics Committee of Flinders University. Thermistor cables were passed subcutaneously and connected to a headpiece fixed to the skull with dental cement. After one-week recovery the unrestrained rats (n=9) were housed singly in a quiet closed temperature controlled (24-26°C) cage. A stocking-mesh bag containing 4 live cockroaches (Periplaneta australasiae) was suddenly introduced into the rat’s cage. We recorded BAT and body temperatures for 30 min and then removed the cockroach bag. The rat approached the bag of cockroaches and attempted to bite or rip the stocking-mesh bag. Maximum increases in BAT and body temperatures (mean ± SEM) were recorded and analysed with repeated measures ANOVA. The increase in BAT temperature (1.1±0.16°C) was significantly greater (P<0.05) than the simultaneously measured increase in body temperature (0.76±0.11°C), suggesting that BAT thermogenesis contributes to the increase in body temperature. Our results suggest that brain regulated sympathetically-controlled BAT thermogenesis contributes to the increase in body temperature occurring when the rat is confronted with a novel salient stimulus.