Effect of berberine on myoelectric activity and transit of the small intestine in rats

The motility of the small intestine in unanesthetized rats receiving berberine sulfate (0.2, 2.0, and 20.0 mg/kg i.p.) was investigated. Motility was determined by two methods: myoelectric activity was monitored with indwelling bipolar electrodes, and intestinal transit was measured by the movement of radiochromium (Na51CrO4). The 20.0-mg/kg dose caused a marked inhibition of spike activity for 21.8 ± 7.0 min and disrupted activity fronts of the migrating myoelectric complex for 212.3 min. Berberine, 2.0 mg/kg i.p., disrupted migrating myoelectric complexes for 64.6 min but spike inhibition was not observed. Transit of the small intestine was significantly (p < 0.001) delayed at 15 and 100 min after the highest dose of berberine. Naloxone blocked the spike inhibition noted with 20.0 mg/kg of berberine but failed to improve transit. Phentolamine blocked spike inhibition and was associated with a significantly earlier return of activity fronts of the migrating myoelectric complex. Animals pretreated with this antagonist tended toward a higher geometric center in transit studies than those injected with berberine alone. Berberine was also administered by various routes (intraperitoneal injection, intravenous injection, orogastric gavage, and intraluminal injection). An intraperitoneal injection was 10-fold more potent than an intravenous injection. Orogastric gavage and intraluminal administration of berberine did not alter intestinal motility. In summary, berberine sulfate significantly inhibits myoelectric activity and transit of the small intestine. This appears to be partially mediated by opioid and α-adrenergic receptors. The antidiarrheal properties of berberine may be mediated, at least in part, by its ability to delay small intestinal transit.