Influence of different barbiturate anesthetics on delta-9-tetrahydrocannabinol effects on spinal monosynaptic reflexes.

Two barbiturates, pentobarbital and methohexital, were used as general anesthetics to evaluate their interactions with the effects of delta-9-tetrahydrocannabinol (delta-9-THC) on spinal monosynaptic reflexes in cats with transected spinal cords and ischemically destroyed brains. In animals initially anesthetized with pentobarbital, delta-9-THC over a wide dosage range produced only an enhancement of the reflex, whereas in methohexital-treated animals only depression was elicited. Because delta-9-THC is known to produce both excitatory and depressant effects in conscious animals, the results of the present study demonstrate that the choice of anesthetic may determine which effects manifest themselves. Therefore, if anesthesia is used in the investigation of any cannabinoid, the possibility of such interactions must be considered when interpreting the results.