Measurement of the levels of neurochemicals such as histamine in the skin can provide insight into the stimulus for an inflammatory response and the mechanism of action of anti-inflammatory treatments.

Top - Administration of the skin irritant ovalbumin at time = 0 produced a rapid and robust increase in the extracellular level of histamine in guinea pig skin. Bottom - Topical application of 1% capsaicin (horizontal bar) to the abdominal skin of anesthetized rats produced a marked increase in PGE2 levels but almost no effect on histamine levels.

Topical application of 1% capsaicin (horizontal bar) to the abdominal skin of anesthetized rats produced a marked increase in PGE2 levels but almost no effect on histamine levels.