Maybe you shouldn't think about the rich, sensuous, mouth-watering taste of dark, fragrant chocolate while you read this.

But if you can't resist, it may be, according to three scientists at the Neurosciences Institute in San Diego, that you are craving not just that taste and texture but also a mild alteration in consciousness similar to that produced by cannabinoids, the psychoactive constituents of the cannabis plant, better known as marijuana.

Chocolate, including cocoa powder, contains three compounds from the N-acylethanolamine group of chemicals that may target the endogenous cannabinoid system in the brain. The substances are not present in cocoa butter.

Just as the brain produces its own version of morphine, it also produces anandamide, a version of tetrahydrocannabinol (THC), the main psychoactive constituent of marijuana. The name comes from the Sanskrit word "ananda," which means "bliss."

In research on rat brains, psychopharmacologist Daniele Piomelli, Ph.D., and colleagues found that although the N-acylethanolamines do not activate brain cannabinoid receptors, they do inhibit the breakdown of anandamide in brain microsomes and intact rat brain cells.

Microsomes are small particles obtained by centrifuging homogenized brain cells, used to test how substances may be metabolized in the brain.

By interfering with the deactivation of anandamide, N-acylethanolamines may prolong its action and thereby produce a heightened sense of well-being, Piomelli speculates.

Although the study has been treated somewhat lightly in the press_and according to Piomelli, elicited worried telephone calls from representatives of chocolate producers concerned with their product's image_it has a very serious side, he told Psychiatric News.

"What we care most about is the therapeutic potential of this concept, not necessarily the therapeutic use of these compounds. Rather, [it is significant] that you may be able to improve mood by blocking the breakdown of anandamide. This is a serious observation. It's not just something cute that we've done so that now we know more about chocolate. The hope is that it may contribute to helping cure mental diseases."

Much is known about the effects of cannabis, one of the world's most popular recreational euphoriants. Scientists first suspected there might be a naturally occurring analogue of plant cannabinoids in the mammalian brain when they discovered a cannabinoid receptor in nerve cells in 1988. The discovery of that analogue in pig brains was reported in 1992, and only within the last year has its existence in human brains been confirmed, according to Piomelli.

Anandamide is a lipid, which is to say anything derived from a fatty acid, and is lipophilic, that is, it has an affinity for other lipids. It is very short acting because it is degraded and inactivated very quickly, Piomelli explained.

"What we did was, we found an enzyme in the brain that breaks down anandamide," said Piomelli. "Clearly the brain needs mechanisms to inactivate neural signaling molecules."

Piomelli believes it is the "nonselective activation of all cannabinoid receptors" when THC is consumed that causes the cannabis "high." The reason that humans don't walk around continually high from their THC analogue is probably related to its highly selective release and rapid breakdown, Piomelli said.

"Very likely anandamide is only produced in certain areas of the brain. At any given time only a particular subset of cannabinoid receptors will be activated (when endogenous anandamide is released). The normal role of anandamide is not to make us high. The normal role is probably to modulate mood, appetite, and pain," among others.

He stressed that the study is not meant to imply that chocolate produces a state approaching that induced by consuming THC. If anandamide breakdown is blocked, its effects will be exaggerated, "but it still will not be like THC" since the area of the brain where anandamide exists is limited, he said.

Piomelli and colleagues are now testing the effects of the chocolate compounds through intraperitoneal injections in rats. The compounds easily cross the blood-brain barrier, he notes.

(Psychiatric News, November 1, 1996)