title: Trigeminal-parabrachial connections: possible pathway for nociception-induced cardiovascular reflex responses.
abstract: Noxious stimulation of dental nerves elicits marked changes in cardiovascular function. In order to investigate central pathways mediating reflex changes in cardiovascular activity, immunohistochemical localization of cells expressing the immediate-early gene, c-fos, was used to identify central nervous responding to noxious electrical stimulation of mandibular, incisor tooth dentin or chemical (capsaicin) stimulation of tooth pulp in the anesthetized rat. Injections of Fluoro-Gold were made in the lateral parabrachial region to identify efferent projections from the spinal trigeminal nucleus. Electrical and chemical stimulation produced similar patterns of Fos-positive neurons in the spinal trigeminal nucleus: subnuclei caudalis, interpolaris and oralis. Fos-positive neurons were most dense in laminae I and II of the dorsomedial subnucleus caudalis with fewer Fos-positive neurons located in the interpolaris and oralis subnuclei. Sham stimulation of tooth dentin and control vehicle injections into the tooth pulp resulted in either a few weakly stained or no Fos-positive neurons in the spinal trigeminal nucleus. Cell bodies double labeled with Fluro-Gold following injections into the parabrachial region and Fos-protein subsequent to electrical stimulation of incisor tooth were present in all three subnuclei of the spinal trigeminal nucleus. The largest number of Fos-positive neurons with efferent projections to the lateral parabrachial region were located in subnucleus caudalis (32.2 +/- 5.3 S.E.M.) and fewer were located in the interpolaris (0.4 +/- 0.4 S.E.M.) and oralis (19.8 +/- 3.5 S.E.M.) subnuclei. The results demonstrate that nociceptive dental input received by the three subnuclei of the spinal trigeminal nucleus, particularly the subnucleus caudalis, is relayed to the lateral parabrachial nucleus.
authors: Faculty of Medicine, Department of Anatomy and Neurobiology, Dalhousie University, Halifax, Nova Scotia, Canada. gva@ac.dal.ca
authors: G V
authors: GV
authors: Allen
authors: B
authors: B
authors: Barbrick
authors: M J
authors: MJ
authors: Esser
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D003804:Dentin / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D009434:Neural Pathways / Q000033:anatomy & histology / Q000503:physiopathology; D009619:Nociceptors / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D011149:Pons / Q000033:anatomy & histology / Q000166:cytology / Q000503:physiopathology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000502:physiology*; D013266:Stilbamidines; D013268:Stimulation, Chemical; D014276:Trigeminal Nerve / Q000033:anatomy & histology / Q000166:cytology / Q000503:physiopathology*
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D016760:Proto-Oncogene Proteins c-fos; D013266:Stilbamidines