Selective myenteric neuronal denervation of the rat jejunum: Differential control of the propagation of migrating myoelectric complex and basic electric rhythm

Abstract

Serosal application of benzalkonium chloride (BAC), a cationic surfactant, was used to selectively ablate the myenteric neurons of the rat jejunum. The myoelectric activity of the BAC-treated area and the areas both orad and caudad to it were assessed. In the jejunal segment devoid of myenteric neurons, the basic electric rhythm (BER) pattern was erratic and the amplitude of the BER was attenuated. The BER frequency of the jejunal area caudad to the BAC-treated area was 30.7 ± 0.73 cycles/min, which was significantly reduced from the normal BER frequency (37.7 ± 0.64 cycles/min). Spike activity was normal in areas both orad and caudad to the treated area, existing in regular cycling bursts (migrating myoelectric complex). Spiking in the treated area did not appear until ~13–17 days after BAC treatment. These spikes, though of greater duration and lower frequency than the adjacent areas, always appeared after an orad burst and were followed by a caudad burst. In addition, the following motility parameters of the regions orad and caudad to the treated area were not significantly different from control animals: burst duration, period, and burst propagation velocity. In conclusion, the present investigation has demonstrated that BAC-induced ablation of the myenteric neurons in the rat jejunum disrupts the BER but not the migrating myoelectric complex propagation. This suggests that the myenteric neurons play a modulatory role in the generation and propagation of the BER, whereas humoral factors or the submucosal neurons may be more important in the control of the migrating myoelectric complex.