The Role of the Rectal Branches of Pelvic Plexus in Defecation and Colonic Motility in a Canine Model

The parasympathetic nerves regulate colonicmotility and defecation. The vagal nerve controlsthe right colon and the pelvic nerve permeates theleft colon and rectum via the rectal branches of thepelvic plexus (RBPP). This investigation aimed tomeasure the functional changes of the colon andrectum after RBPP-transection for over sixmonths.RBPP-transection was performed in 15 dogs.Five dogs each were sacrificed immediately, onemonth, and six months after RBPP-transection. Thestool condition, colorectal transit, defecationreflex, colorectal response to electrical stimulation,and pathological degeneration was investigatedprior to, one month after, and six months afterRBPP-transection.Four of the 5 dogs observed had loose stool onemonth after RBPP-transection, and one of the 3 hadrecovered six months later. Half transit time (HTT)at transverse colon got longer in six of the 8 in onemonth. Six months later, HTT got shorter in three ofthe 4 than that of one month. Defecation reflex wasnot observed one month after RBPP-transection,but noted in two of the 5 six months later.These results may suggest that vagal nervecompensates for the oral site of the left colon afterdenervation of the pelvic nerve which is originallydistributed.