[Probable inhibition of a bacterial collagenase by serotonin]

We have previously demonstrated that intraperitoneal injections in rats of collagenase (from Clostridium histolyticum) are followed by severe lesions. Here we show that the injection of collagenase together with serotonin has no or only small effects. It appears to be partly due to serotonin. Creatinin and sulfate which form an injectable complex with serotonin have no influence on this phenomenon. The part of pH 4,4 of the injected solution is discussed. These facts suggest that serotonin may perhaps lower the collagenolysis and be thus responsible for the fibrogenetic effects of carcinoid tumors, many of these being characterised by their high production of serotonin.