C-terminals in the mouse branchiomotor nuclei originate from the magnocellular reticular formation

• Published in: Neuroscience letters Vol. 548; pp. 137 - 142
• Main Authors: Matsui, Toshiyasu, Hongo, Yu, Haizuka, Yoshinori, Kaida, Kenichi, Matsumura, George, Martin, Donna M., Kobayashi, Yasushi
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 26.08.2013
• Subjects: Animals; Brainstem; Branchiomotor neurons; C-terminals; Cholinergic neurons; Cholinergic Neurons - cytology; Cholinergic Neurons - metabolism; Female; Homeobox Protein PITX2; Homeodomain Proteins - metabolism; Male; Mice, Inbred ICR; Motor Neurons - cytology; Motor Neurons - metabolism; Neural Pathways - cytology; Neural Pathways - metabolism; Presynaptic Terminals - metabolism; Presynaptic Terminals - ultrastructure; Reticular formation; Reticular Formation - cytology; Reticular Formation - metabolism; Transcription Factors - metabolism; Gi; Brainstem; Reticular formation; py; Gr; Xd; pyx; VIIn; Cu; Vm; Amb; XIIm; SO; Cholinergic neurons; XIm; VIIm; VeM; cc; Pr; PnC; VeSp; LPGi; IO; IRt; MdD; AP; LRt; PCRt; Sol; C-terminals; VSpO; RF; VSpC; Branchiomotor neurons; VSpI; MdV; caudal part of spinal trigeminal nucleus; facial nerve; pyramidal decussation; ambiguous nucleus; cuneate nucleus; hypoglossal nucleus; caudal part of pontine reticular nucleus; medial vestibular nucleus; inferior olive; nucleus of the accessory nerve; nucleus of the solitary tract; dorsal part of the medullary reticular nucleus; dorsal motor nucleus of vagus nerve; intermediate reticular nucleus; pyramidal tract; prepositus nucleus; trigeminal motor nucleus; interpolar part of spinal trigeminal nucleus; area postrema; spinal vestibular nucleus; gigantocellular reticular nucleus; lateral reticular nucleus; parvicellular reticular nucleus; superior olive; gracile nucleus; central canal; lateral paragigantocellular nucleus; facial nucleus; oral part of spinal trigeminal nucleus; ventral part of the medullary reticular nucleus
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2013.05.063

•C-terminals in branchiomotor nuclei originate from brainstem cholinergic neurons.•These C-terminal origins include both Pitx2-positive and Pitx2-negative populations.•C-terminals show simultaneous bilateral projections to branchiomotor nuclei.•C-terminals may function in the modulation of synchronized orofacial behaviors. 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.