Hi, Deena,
Outside of whether the opioid receptors are covered for small amounts, which the others have already addressed, there is what's called "incentive salience."
Quote:
Incentive salience is a motivational "wanting" attribute given by the brain to reward-predicting stimuli. This "wanting" is unlike "liking" in that liking is a pleasure immediately gained from consumption or other contact with stimuli, while the "wanting" of incentive salience is a motivational magnet quality of a stimulus that makes it a desirable and attractive goal, transforming it from a mere sensory experience into something that commands attention, induces approach, and causes it to be sought out.
That's a fancy way to say that the cues of alcohol (sight, smell, sitting in a bar, etc) become salient--that is, they command attention over other things--and become an incentive in and of themselves.
So just being in the gourmet shop and exposed to the cues of even tiny amounts of wine may be triggering strong interest or even craving and driving a desire to pick up the tablespoon of wine and consume it, whether or not there is an endorphin reward.
For that reason, I personally would tend to partially disagree with Eskapa's statement on the OSL board that Bardo linked, that "It is not worth taking the opioid antagonist for 1 or 2 grams of alcohol!"
This is an opportunity to begin to extinguish the incentive salience in that context. You're not just extinguishing the alcohol reward on TSM, you are also extinguishing all the cues that have acquired value in themselves.
You could possibly do this while not on Nal by doing the "wine-tasting" thing, that is, holding the wine, smelling it, taking a sip, tasting, but not swallowing. If you spit it out, then you are being exposed to the cues without getting the future opioid reward.
If you don't think you can spit it out, then personally I think you are risking strengthening the incentive salience if you get even a tiny opioid reward. And that will maintain and strengthen the incentive to act on the cues. So to me, the safest and most effective thing to do would be to take the Nal, go happily to the shop, taste the tiny sample of wine, and expose yourself on Nal to the cues.
In this way, your brain has an opportunity to recalculate the value of those cues. They may still have value, in terms of being pleasant and interesting in themselves, but your brain will make a prediction error of expecting opioid reward TOO. It won't get that on Nal, so it will start to revise its opinion of those cues and their value.
In short (am I ever short?) it kinda seems to me like the perfect extinction setup on Nal.
For the geeks, a challenging but relevant article on dopamine, prediction error, and incentive salience:
http://www-psych.stanford.edu/~dnl/pdf/ ... ntague.pdf