The bulb at the base of each hair contains the stinging liquid that includes formic acid , histamine , acetylcholine and 5 - hydroxytryptamine ( serotonin ) .
球茎位于毛的基部,包含了刺毛液体,包含蚁酸,组织胺,乙酰胆碱和5-羟色胺(血清素)。
Histamine released by these cells causes small blood vessels to dilate , giving rise to the well-known symptoms such as itching and swelling in the mouth , skin rash , itchy or runny nose or diarrhoea .
Naturally occurring small molecules which bind to gpcrs include adrenaline , prostaglandins , dopamine , somatostatin and adenosine . Drug-like small molecules which bind to gpcrs include caffeine , morphine , heroin and histamine .