Neya T, Takaki M, Nakayama S
Acta Med Okayama. 1984 Feb;38(1):21-7. doi: 10.18926/AMO/30367.
In guinea pigs whose pelvic nerves were bilaterally sectioned, afferent stimulation of rectoanal branches of the pelvic nerve (PAS) could produce an intense contraction in the rectum similar to propulsive contractions elicited during defecation. The mechanism of this reflex was analyzed. Rectal contraction by PAS was abolished after transecting the spinal cord at T13 or sectioning the lumbar splanchnic nerves (LSN) or lumbar colonic nerves (LCN), but was unaffected by severing the intermesenteric and hypogastric nerves. Rectal contraction induced by PAS was abolished peripherally by atropine, guanethidine or yohimbine, while propranolol had no affect. Yohimbine antagonized the inhibitory effect of LSN or LCN stimulation on atropine-sensitive rectal contractions. It may, therefore, be concluded that PAS blocks the inhibition, by LCN efferents acting through alpha-adrenoreceptors, of cholinergic neurons in the myenteric plexus, thus facilitating recto-rectal propulsive contractions initiated by the defecation reflex.
在双侧切断盆腔神经的豚鼠中，对盆腔神经直肠肛管分支进行传入刺激（PAS）可使直肠产生强烈收缩，类似于排便时引发的推进性收缩。分析了这种反射的机制。在T13水平横断脊髓、切断腰内脏神经（LSN）或腰结肠神经（LCN）后，PAS引起的直肠收缩消失，但切断肠系膜间神经和腹下神经则无影响。PAS诱导的直肠收缩可被外周给予的阿托品、胍乙啶或育亨宾消除，而普萘洛尔则无作用。育亨宾可拮抗LSN或LCN刺激对阿托品敏感的直肠收缩的抑制作用。因此，可以得出结论，PAS通过作用于α-肾上腺素能受体的LCN传出神经阻断了肠肌丛中胆碱能神经元的抑制，从而促进了由排便反射引发的直肠-直肠推进性收缩。
