He says "O-4394 and O-4395 exhibit similar in vitro potencies to eDelta(9)-THCV as CB(1) receptor ligands and as antagonists of cannabinoid receptor agonists and can antagonize Delta(9)-tetrahydrocannabinol in vivo."

But what I get from that is these opioids act as THC agonists and block the action of other cannabinoid agonists. This does not answer his question.

I would think that the opposite would occur in that having both THC and tramadal would increase the rate and production of MAO and COMT, enzymes which break down many types of neurotransmitters. This would in fact decrease the amount of neurotransmitters making it to receptors after your blood THC/Tramadal levels are low enough.

This suggests that enzymes are not at work. Perhaps the down regulation of cannabinoid receptors, which has been shown to happen after being exposed to large(ish) amounts of cannabinoids, causes an increase in sensitivity to Tramadal?