Histamine is a neurotransmitter that also has peripheral functions such as the regulation of gastric acid secretions, allergic responses, etc. I know that opioids stimulate a release of histamine but I want to know how?
What exactly I would like answered is:
Which of the opioid receptors are involved in the histamine release that opioids stimulate and to what extent are they?
How does the activation of the opioid receptors in question lead to a release of histamine?
Are there any ways of suppressing the histamine release stimulated by opioids without compromising the analgesia they elicit?
I would like an answer, not just links. However I would like you to cite journal articles, although a formal reference list is not required so long as I can easily find the link to the abstract/full article.