The anteroventral preoptic region (AVPO) of the hypothalamus is involved in both temperature and breathing regulation. This area densely express cannabinoid receptors type 1 (CB1) that modulates both excitatory and inhibitory synaptic transmission. However, it is still unknown if the endocannabinoid system located in the AVPO participates in breathing control and thermoregulation. Therefore, we tested the participation of CB1 in the AVPO in the modulation of ventilation and thermal control during normoxia and hypoxia. To this end, body temperature (Tb) of Wistar rats was monitored by datallogers and ventilation (V_E) by whole body plethysmography before and after intra-AVPO microinjection of AM-251 (CB1 antagonist, 50 and 100 pmol) followed by 60 min of hypoxia exposure (7% O₂). Intra-AVPO microinjection of the higher dose of AM-251 increased ventilation but did not change Tb under resting conditions. Exposure of rats to 7% of inspired oxygen evoked typical hypoxia-induced anapyrexia and hyperventilation after vehicle microinjection. The higher dose of the cannabinoid antagonist increased the hypoxia-induced hyperventilation, in the same magnitude as observed under normoxic condition, whereas the drop in Tb elicited by hypoxia was attenuated. Therefore, the present results demonstrate that the endocannabinoid system acting on CB1 receptors in the AVPO exerts a tonic inhibitory modulation on breathing but seem not be involved in thermoregulation during restingconditions. In addition, activation of CB1 receptors in the AVPO stimulate thermal response during hypoxia, reducing energetically expensive responses, such as the hypoxic hyperventilation.

下丘脑的前腹视前区（AVPO）参与温度和呼吸调节。该区域密集表达1型大麻素受体（CB1），可调节兴奋性和抑制性突触传递。但是，尚不清楚位于AVPO的内源性大麻素系统是否参与呼吸控制和体温调节。因此，我们测试了常氧和低氧期间CB1在AVPO中参与通气和热控制的调节。为此，在进行AVPO微量注射AM-251（CB1拮抗剂，50和100 pmol）之前和之后，通过数据体积描记器监测Wistar大鼠的体温（Tb），并通过全身体积描记法监测通气（V _E），随后监测60分钟低氧暴露（7％O ₂）。较高剂量的AM-251的AVPO内显微注射可增加通气，但在静息条件下不会改变Tb。在车辆显微注射后，将大鼠暴露于7％的吸氧引起典型的低氧诱导的厌氧和过度换气。较高剂量的大麻素拮抗剂使缺氧引起的过度通气增加，与在常氧条件下观察到的幅度相同，而由缺氧引起的Tb下降则减弱。因此，目前的结果表明，作用于AVPO中CB1受体的内源性大麻素系统对呼吸产生了强直抑制性调节作用，但似乎在休息条件下并未参与温度调节。此外，AVPO中CB1受体的激活会刺激缺氧期间的热反应，从而降低能量上昂贵的反应，