Pathophysiological relevance of serotonin.

The present article deals with the pathophysiological role of serotonin in cardiovascular disease and in other disorders that are accompanied by cardiovascular pathophysiological events. The distribution of serotonin over various organs and tissues and the presence of several types of 5-HT receptors would suggest a rather important physiological role of serotonin. However, a modest serotonergic role could only be shown for the microcirculation and for the regional circulation of the brain and the intestinal wall. An important pathological role of serotonin in the carcinoid syndrome, in migraine, and in peripheral vascular disease is beyond debate, although many details remain to be established. The possibility that serotonergic mechanisms contribute to Raynaud's phenomenon and other vasospastic disorders is the subject of present discussions, although firm evidence for this view is not widely available. An involvement of peripheral serotonin in the genesis and maintenance of essential hypertension seems very unlikely, although vascular damage due to hypertension is probably enhanced by serotonin released from aggregating platelets. This ancillary process is, in particular, to be anticipated in older patients, with vascular walls predamaged by atherosclerosis. For this reason, pharmacological blockade of 5-HT2 receptors may be of potential therapeutic benefit in this category of patient. Finally, the involvement of central serotonergic mechanisms in hypertensive disease cannot be ruled out.