title: Nociceptive afferents to the premotor neurons that send axons simultaneously to the facial and hypoglossal motoneurons by means of axon collaterals.
abstract: It is well known that the brainstem premotor neurons of the facial nucleus and hypoglossal nucleus coordinate orofacial nociceptive reflex (ONR) responses. However, whether the brainstem PNs receive the nociceptive projection directly from the caudal spinal trigeminal nucleus is still kept unclear. Our present study focuses on the distribution of premotor neurons in the ONR pathways of rats and the collateral projection of the premotor neurons which are involved in the brainstem local pathways of the orofacial nociceptive reflexes of rat. Retrograde tracer Fluoro-gold (FG) or FG/tetramethylrhodamine-dextran amine (TMR-DA) were injected into the VII or/and XII, and anterograde tracer biotinylated dextran amine (BDA) was injected into the caudal spinal trigeminal nucleus (Vc). The tracing studies indicated that FG-labeled neurons receiving BDA-labeled fibers from the Vc were mainly distributed bilaterally in the parvicellular reticular formation (PCRt), dorsal and ventral medullary reticular formation (MdD, MdV), supratrigeminal nucleus (Vsup) and parabrachial nucleus (PBN) with an ipsilateral dominance. Some FG/TMR-DA double-labeled premotor neurons, which were observed bilaterally in the PCRt, MdD, dorsal part of the MdV, peri-motor nucleus regions, contacted with BDA-labeled axonal terminals and expressed c-fos protein-like immunoreactivity which induced by subcutaneous injection of formalin into the lip. After retrograde tracer wheat germ agglutinated horseradish peroxidase (WGA-HRP) was injected into VII or XII and BDA into Vc, electron microscopic study revealed that some BDA-labeled axonal terminals made mainly asymmetric synapses on the dendritic and somatic profiles of WGA-HRP-labeled premotor neurons. These data indicate that some premotor neurons could integrate the orofacial nociceptive input from the Vc and transfer these signals simultaneously to different brainstem motonuclei by axonal collaterals.
authors: Department of Anatomy and Histology and Embryology, and K. K. Leung Brain Research Centre, the Fourth Military Medical University, Xi'an, China.
authors: Yulin
authors: Y
authors: Dong
authors: Jinlian
authors: J
authors: Li
authors: Fuxing
authors: F
authors: Zhang
authors: Yunqing
authors: Y
authors: Li
mesh_terms: D000344:Afferent Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism*; D001692:Biological Transport; D019921:Biotinylation; D003911:Dextrans / Q000378:metabolism; D005154:Facial Nerve / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D005557:Formaldehyde / Q000008:administration & dosage / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007002:Hypoglossal Nerve / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D008046:Lip; D008297:Male; D009046:Motor Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D059225:Nociception / Q000187:drug effects / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012235:Rhodamines / Q000378:metabolism; D013266:Stilbamidines / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism; D014279:Trigeminal Nucleus, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate / Q000378:metabolism
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D003911:Dextrans; D016760:Proto-Oncogene Proteins c-fos; D012235:Rhodamines; D013266:Stilbamidines; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D005557:Formaldehyde; C005358:tetramethylrhodamine