Clinical Import of Serotonin Activity in the Bladder and Urethra

It has been observed in animal studies that 5-hydroxytryptamine produces bladder contractions. The role of 5-hydroxytryptamine in human vesicourethral function was studied by administering 75 mg. clomipramine daily for 4 days to 8 patients with neurogenic bladder dysfunction. Clomipramine inhibits the uptake of serotonin into 5-hydroxytryptamine containing presynaptic nerve endings and, thus, makes more neurotransmitter available to the postsynaptic site. The intravesical volume, at which first detrusor reflex activity was observed, showed a decrease from 329.5 to 178.5 ml. after clomipramine therapy. The residual urine also decreased from 111.25 to 30.0 ml. No side effect was observed. Further investigations involving a larger number of patients are indicated to study the possible use of serotonin activity in the bladder for promoting bladder emptying.