Respiratory and body temperature modulation by adenosine A1 receptors in the anteroventral preoptic region during normoxia and hypoxia

The present study was undertaken to investigate adenosine as a simultaneous mediator of hypoxia-induced hyperventilation and regulated hypothermia in the anteroventral preoptic region (AVPO).the thermointegrative region of the central nervous system (CNS). Accordingly, we predicted that injection of aminophylline and DPCPX, non-selective and A, receptor antagonists, respectively, into the AVPO would exacerbate the ventilatory response and lessen the drop in body temperature (T-b) caused by hypoxia. We measured ventilation (V) and Tb of conscious Wistar rats before and after AVPO injection of aminophylline (I and 10 mu g/100nL) or DPCPX (17.5 and 175ng/100nL), or their respective vehicles, followed by 30 min of hypoxia (7% O-2)Vehicles and the lower doses of both antagonists had no effect on V and T-b during normoxia or hypoxia. The higher doses of arninophylline and DPCPX increased (P < 0.05) the hypoxia-induced hyperventilation, whereas the drop in T-b elicited by hypoxia was attenuated (P < 00.05) by DPCPX only. This higher DPCPX dose also increased T-b during normoxia. The present data is consistent with the notion that adenosine plays an inhibitory role in respiratory and metabolic regulation, in a way that A, receptors stimulation in the AVPO inhibits ventilatory drive during hypoxia and tonically modulates basal Tb. (c) 2005 Elsevier B.V. All rights reserved.