Detection of Microwave Heating in 5-Hydroxytryptamine-Induced Hypothermic Mice

Abstract

The intraperitoneal injection of 5-hydroxytryptamine (5-HT) in unrestrained and unanesthetized mice held at 22°C causes a hypothermia which is maximal after approximately 15 min. When mice injected with 5-HT were held in a controlled environment of 22°C and 50% relative humidity and exposed to microwaves (2450 MHz, cw) at $1 {\rm mW}/{\rm cm}^{2}$ for 15 min, significant significant increases were observed in the body temperature of these mice compared to 5-HT-treated sham-irradiated mice. The magnitude of the response was related to power density ( $10>5>1 {\rm mW}/{\rm cm}^{2}$ ). Saline-injected mice exposed for 15 min at 10 mW/ cm2 (specific absorption rate = 7.2 m W/g) showed no significant increase in body temperature compared to saline-injected sham-irradiated mice. The hypothermia induced by 5-HT in mice was also found to be affected by ambient temperature alone. Increases in ambient temperature above 22°C, in the absence of microwaves, caused a concomitant incr...