Descending monoaminergic pathways projecting to the spinal defecation center enhance colorectal motility in rats

摘要

The central regulating mechanisms of defecation, especially roles of the spinal defecation center, are still unclear. We have shown that monoamines including norepincphrine, dopamine, and serotonin injected into the spinal defecation center cause propulsive contractions of the colorec-tum. These monoamines are the main neurotransmitters of descending pain inhibitory pathways. Therefore, we hypothesized that noxious stimuli in the colorectum would activate the descending monoaminergic pathways projecting to the spinal defecation center and that subsequently released endogenous monoamine neurotransmitters would enhance colorectal motility.