Here, using the acute rat model of reflex apnea, we hypothesized that the attenuation of 5-HT-induced apnea and the increased upper airway tone produced by nodose ganglion dronabinol injection would be reversed by IP pre-treatment with AM251, a CB1 antagonist, but not by pre-treatment AM630, a CB2 antagonist. Here, CNR2 is linked to Apnea.