[Inhibitory effects of agmatine on stress-induced hyperthermia in rats]

To examine whether agmatine (AGM) would alter stress-induces hyperthermic response.

Sixty-one male SD rats were randomly divided into three experiments. Each experiment was divided into control group and AGM group. During the experiments, the animals were maintained in a chamber at 22℃. ①Effects of intraperitoneal injecting 40 or 80 mg/kg AGM on normal core temperature and activity were observed in undisturbed rats using radiotelemetry (n=8). ②Stress-induced hyperthermia model was established by placing rats in an open-field chamber for 60 min. Rats were dosed intraperitoneally with AGM or saline, and placed immediately inside the open-field chamber. Core temperature and motor activity were monitored by radiotelemetry in an open-field chamber (n=7~8). ③Effect of AGM on energy metabolism was measured by Columbus Oxymax Lab Animal Monitoring System (n=7).

①Rats administered with 80 mg/kg AMG showed significant hypothermic responses (-0.46±0.11)℃, while 40 mg/kg AMG had no significant effect on the normal core temperature. ②Core temperature of control group increased by (0.78±0.16)℃ during open-field exposure, whereas rats administered 40 and 80 mg/kg AGM underwent a (0.34±0.11)℃ and (0.81±0.14)℃ reductions in core temperature within 60 min, respectively. ③Oxygen consumption and energy metabolism were significantly reduced by AGM (80 mg/kg).

The data demonstrated that AGM induced hypothermic responses in rats and reversed stress-induced hyperthermia, and its effect might attribute to the suppression of energy metabolism.