Aren’t most drugs that people might take for recreational purposes already present in measureable quantities in the brain? Or if not that precise drug itself, then something very similar? After all, if your brain didn’t already have receptors for the drug it wouldn’t do a damn thing when you took it.
How about some endorphins?
No, not even close. Some drugs are natural analogues of existing brain chemicals, but the vast majority are competitors, antagonists, triggers etc. In other words they cause the brain to release its natural reserves of chemicals, or cause it to produce more and more of those chemicals, despite natural threshold levels having been exceeded. Those types of drugs don’t mimic natural ‘pleasure’ chemicals directly, they just stuff up the normal controls on the release and production of those substances. The reason these chemicals work isn’t because the brian has natural receptors for them, it’s because they either bind to and disable the natural chemicals in the brain, or else bind to receptors intended for completely different chemicals. It’s much like the way carbon monoxide binds very effectively to haemoglobin, or lead and arsenic bind very effectively to a variety of enzymes. That doesn’t mean that your body has receptors for CO, As or Pb. Like virtually all poisons they work by binding to sites that were never developed to cope with that particular type of shit entering your system.
“Unreal psychedelic episodes” is putting it mildly. I’ve heard that these experience can sound uncannily like UFO encounters. Seeing that DMT is a naturally occuring neurochemical, some have suggested that those “UFO abductions” might be the result of a large release of naturally occurring DMT.
Also–it’s interesting that DMT is most active during deep REM stages–Dream time, in other words.