what actions does histamine have in body tissue?

Answer 1

Histamine serves two major functions. In somatic cells, it serves as part of the primary immune response to injury, aiding and abetting in the inflammatory process that speeds immune cells to the site of injury/infection.

In nerve cells, histamine serves as a neurotransmitter, regulating sleep patterns as well as having a small effect on euphoria (being similar in binding to receptors as dopamine).