title: C-terminals in the mouse branchiomotor nuclei originate from the magnocellular reticular formation.
abstract: Large cholinergic synaptic boutons called "C-terminals" contact motoneurons and regulate their excitability. C-terminals in the spinal somatic motor nuclei originate from cholinergic interneurons in laminae VII and X that express a transcription factor Pitx2. Cranial motor nuclei contain another type of motoneuron: branchiomotor neurons. Although branchiomotor neurons receive abundant C-terminal projections, the neural source of these C-terminals remains unknown. In the present study, we first examined whether cholinergic neurons express Pitx2 in the reticular formation of the adult mouse brainstem, as in the spinal cord. Although Pitx2-positive cholinergic neurons were observed in the magnocellular reticular formation and region around the central canal in the caudal medulla, none was present more rostrally in the brainstem tegmentum. We next explored the origin of C-terminals in the branchiomotor nuclei by using biotinylated dextran amine (BDA). BDA injections into the magnocellular reticular formation of the medulla and pons resulted in the labeling of numerous C-terminals in the branchiomotor nuclei: the ambiguous, facial, and trigeminal motor nuclei. Our results revealed that the origins of C-terminals in the branchiomotor nuclei are cholinergic neurons in the magnocellular reticular formation not only in the caudal medulla, but also at more rostral levels of the brainstem, which lacks Pitx2-positive neurons.
authors.affiliation: Department of Anatomy and Neurobiology, National Defense Medical College, Tokorozawa, Saitama 359-8513, Japan.
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Matsui
authors.forename: Yu
authors.initials: Y
authors.lastname: Hongo
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Haizuka
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kaida
authors.forename: George
authors.initials: G
authors.lastname: Matsumura
authors.forename: Donna M
authors.initials: DM
authors.lastname: Martin
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D059329:Cholinergic Neurons / Q000166:cytology* / Q000378:metabolism*; D005260:Female; D018398:Homeodomain Proteins / Q000378:metabolism*; D008297:Male; D008813:Mice, Inbred ICR; D009046:Motor Neurons / Q000166:cytology / Q000378:metabolism; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure*; D012154:Reticular Formation / Q000166:cytology* / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D000097577:Homeobox Protein PITX2
chemical_list: D018398:Homeodomain Proteins; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2
keywords: AP; Amb; Brainstem; Branchiomotor neurons; C-terminals; Cholinergic neurons; Cu; Gi; Gr; IO; IRt; LPGi; LRt; MdD; MdV; PCRt; PnC; Pr; RF; Reticular formation; SO; Sol; VIIm; VIIn; VSpC; VSpI; VSpO; VeM; VeSp; Vm; XIIm; XIm; Xd; ambiguous nucleus; area postrema; caudal part of pontine reticular nucleus; caudal part of spinal trigeminal nucleus; cc; central canal; cuneate nucleus; dorsal motor nucleus of vagus nerve; dorsal part of the medullary reticular nucleus; facial nerve; facial nucleus; gigantocellular reticular nucleus; gracile nucleus; hypoglossal nucleus; inferior olive; intermediate reticular nucleus; interpolar part of spinal trigeminal nucleus; lateral paragigantocellular nucleus; lateral reticular nucleus; medial vestibular nucleus; nucleus of the accessory nerve; nucleus of the solitary tract; oral part of spinal trigeminal nucleus; parvicellular reticular nucleus; prepositus nucleus; py; pyramidal decussation; pyramidal tract; pyx; reticular formation; spinal vestibular nucleus; superior olive; trigeminal motor nucleus; ventral part of the medullary reticular nucleus