The mechanism of multidirectional effects of serotonin on the motility of the stomach and colon

Abstract

Trial objective: study the mechanism of multidirectional effect of Serotonin adipinate on gastric and colon motor activity. Materials and methods: experiments were carried out on Wistar rats (N83) in surgical anesthesia. An electromyogram and hydrostatic pressure in the cavities of organs was registered using an amplifier BioAmp ML132 (Adinstruments, Australia), an analog-to-digital converter Maclab 8e (Adinstruments, Australia), a computer Масintosh Performa 6400/180 and a software program Chart 4.2.3. Trial findings: it was established that intra-arterial injection of Serotonin adipinate at a dose of 0.05 mg/kg and 0.1 mg/kg causes stimulatory and inhibitory gastric reactions; at a dose of 0.15 mg/kg - only stimulatory ones. Colon appeared to have only stimulatory reactions. It was also found that intravenous injection of Serotonin adipinate does not intensify stomach and colon contraction. Conclusion. Organs’ stimulatory reactions occur due to activation of muscle 5HT-receptors, inhibitory ones - due to activation of presynaptic 5HT-receptors, locating on organ’s adrenergic terminals, and ejection of inhibitory transmitter noradrenaline by them. When using Serotonin adipinate in experiment and in clinical practice, it is necessary to take into account that the organs’ effect from serotonin administration into body may be dual: inhibitory at low doses and stimulatory at higher ones.