Involvement of adenosine receptors in mouse thermoregulation.

The effects of the activation of adenosine receptors on core body temperature of mice have been studied in the present investigation. Intraperitoneal (i.p.) injection of non-selective adenosine agonists 5'-N ethyl- carboxamide adenosine (NECA; 0.001, 0.01 and 0.05 mg/kg), R-(N(6)-phenylisopropyl)-adenosine (R-PIA; 0.01, 0.1 and 0.25 mg/kg) and selective A(1) adenosine agonist N(6)-cyclohexyladenosine (CHA; 0.1, 0.25 and 0.4 mg/kg) reduced core body temperature. However, R-PIA and CHA were less potent than NECA in reducing the core body temperature. Theophylline (12.5, 25 and 50 mg/kg) blocked the hypothermia of the adenosine agonists. Pre-treatment of animals with selective A(1) adenosine antagonist 8-phenyltheophylline (8-PT; 0.5, 1 and 2 mg/kg) decreased the hypothermic response of CHA but not of NECA and R-PIA. 8-PT potentiated the hypothermia induced by R-PIA. These results suggest that activation of both A(1) and A(2) adenosine receptors decreases core body temperature in mice.