Is a trigeminal nociception-induced cardiovascular response related to the trigemino-vagal reflex?

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 10671883
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Surgical dentistry
• Research Institution: The University of Tokushima
• Principal Investigator: NAKAJO Nobuyoshi Tokushima-Univ., Sch. Dentistry, Dental Hospital, Dept. dental Anesthesiology, Professor, 歯学部・附属病院, 教授 (80069046)
• Co-Investigator(Kenkyū-buntansha): EDUCHI Satoru Tokushima-Univ., Sch. Dentistry, Dental Hospital, Dept. dental Anesthesiology, Research Associate, 歯学部・附属病院, 助手 (20263866) ; TOMIOKA Shigemasa Tokushima-Univ., Sch. Dentistry, Dental Hospital, Dept. dental Anesthesiology, Associate Professor, 歯学部・附属病院, 助教授 (70188770)
• Project Period (FY): 1998 – 2001
• Keywords: Vagal Reflex / Nociception / Trigeminal Nerve / Cardiovascular Response / Dentistry / Ventrolateral Medulla

Research Abstract

We studied effects of electrical stimulation of the inferior alveolar nerve (IAN) and medulla on arterial blood pressure (ABP) in cats. Electrical stimulation of dorsomedial medulla, infratrigeminal nucleus (IFT) and the rostral ventrolateral medulla (RVLM) which has neurons labeled retrogradely by injection of WGA HRP into the unilateral substantia intermedia lateralis of the thoracical spinal cord and containing phenylethanolamine-N-methyl transferaseinduced significant vasopressor response. Vasopressor response on IFT always mimics vasopressor response on IAN. Vasodepressor responses induced when the caudal ventrolateral medulla just ventral to ambiguus nucleus, lateral tegmental field, the trigeminal nucleus interpolaris, trigeminal spinai tract and paramedian reticular nucleus were stimulated. However these vasodepressor responses did not similar to vasodepressor response on TDR and could be almost vagal induced cardio-vascular response. Only after spinalization and electrical stimulation of RVLM lesion, basal ABP decreased and TDR completely disappeared. In medulla, the distribution of possible inhibitory synaptic ligands was mapped using immunohistochemical techniques. It demonstrated that noradrenergic, glycinergic and GABAergic neurons and neurons for adrenaliine α2A receptor, GABAA, GABAB and glycine receptors were also distributed along the sympatho-reflexive route including RVLM and IFT etc. These results suggest that TDR may be negative feedback response to sympathetic nervous system, readily induced by noxious stimulation in the trigeminal region whenever basal ABP and HR are high and that TDR is induced by inhibiting vasoexciting centrer, RVLM through trigeminal nucleus and reticular formation.