Horseradish peroxidaseを用いた逆行性軸索内追跡法によるネコ胃の迷走神経支配の研究—副交感性節前線維の起始細胞の局在について

A STUDY OF THE VAGAL INNERVATION OF THE CAT STOMACH BY MEANS OF RETROGRADE AXOPLASMIC TRANSPORT OF HORSERADISH PEROXIDASE:ON THE LOCALIZATION OF THE ORIGINS OF THE PREGANGLIONIC FIBERS

I．はじめに

　胃壁に散在する粘膜下神経叢および筋層間神経叢の神経細胞に終止する副交感性節前線維の起始細胞が，迷走神経背側核にあることは1905年Kosaka　＆　Yagita^11）がイヌとウサギについて変性実験を行なつて以来多くの報告がある^14,20）。

　この迷走神経遠心路は胃運動に対し促進的に作用し，胃の抑制活動は交感神経性の内臓神経を介することが一連の生理学的研究により知られている^12,18,19）。しかし一方，迷走神経は胃の促進運動のみならず抑制効果をももたらすという報告があり^13,16,25），Laughton^14）はネコ迷走神経背側核の刺激は一般には胃の収縮を来すが，胃が過緊張の状態にある時は，迷走神経刺激により緊張の低下を来すと報告した。また陳^3），沖中^23），沖中ら^24）は変性実験の結果から，松尾^17）は電気刺激による検索から迷走神経内に胃運動の促進性線維と頸部交感神経節由来の交感神経性抑制線維が混在していると結論した。さらに近年銭場ら^27），銭場^29,30）も一連の生理学的研究から，胃運動の調節中枢は迷走神経背内側核，背外側核，孤束核およびこれらに近接する網様体背側部にあるとし，これら一円の部位に胃運動の促進および抑制の両反応点が存在することを見出した。それ故，胃運動の延髄内調節中枢に関して得られた成績の多くは，電気生理学的方法に基づくものであり，形態学的に延髄内の胃運動中枢の局在を同定する努力はGetz＆Sirnes^7）をはじめいくつかの報告が見られるが，従来の逆行性神経細胞変性法に内在する困難性のためにそれらの所見は一致を見ていない。

The origins of the vagal preganglionic fibers tothe plexuses of Auerbach and Meissner in thestomach wall have been investigated by the horse-radish peroxidase (HRP) method. HRP was injectedinto nine parts of the gastric wall in fifteen catsand the retrogradely labelled neurons were identifiedwith frozen serial sections.

1) HRP positive neurons were found evenly inboth sides of the dorsal motor nuclei regardless ofinjection sites and there was no evidence of asym-metry in the distribution of HRP positive cells.

2) HRP positive neurons were present through-out the rostrocaudal extent and were principallydistributed in the medial aspect of the dorsal motornucleus, although a few-stippled cells were foundin the lateral portion as well.

3) Below the level of the obex, HRP positiveneurons were also found in the medial solitarynucleus in most cases except for one in which HRPinjection was done along the gastric large curvature.

4) Small labelled neurons were also found in thecentral gray of the upper cervical spinal cord wherethe medial solitary nucleus or the dorsal motornucleus were no longer identifiable.

These results provide evidence that the cells inthe dorsal motor nucleus are donors of the pregan-glionic vagal fibers to the stomach and they appearto have a longitudinal topographic representationin the medial side of the dorsal motor nucleus.

In addition, neurons in the caudal half of themedial solitary nucleus appear to provide anothersource of the vagal preganglionic fibers to thestomach.

The result of this observation shows that thestomach is dually innervated by the dorsal motorand the medial solitary nuclei and that these twonuclei may subserve different roles in maintaininggastric activity.