Inputs to nucleus pontis caudalis from adjacent trigeminal areas.
Recent studies suggest that the nucleus pontis caudalis (nPontc) plays a role in patterning mastication through interactions with the adjacent lateral tegmentum. In this study, we used in vitro intracellular recording and staining to describe the basic membrane properties and morphology of nPontc neurones and to further explore interactions with adjacent structures, using coronal sections of the brainstem of 78 rats, aged 9-28 days. Neurones were large, with dendrites that spread in all directions, and about 64% fired tonically even in the absence of synaptic inputs. Tonic neurones were predominant in the centre of the nucleus. Electrical stimulation of all regions of the nPontc produced mixed excitatory and inhibitory effects on interneurones of lateral tegmental nuclei. Focal inactivation of the dorsal nPontc with injections of tetrodotoxin also had mixed effects on the spontaneous firing of both interneurones and motoneurones but similar injections in the ventral nPontc produced mostly increases of firing. Sixty-five percent of nPontc neurones received synaptic inputs from the lateral tegmental areas and most of these (68%) were excitatory and mediated by glutamatergic receptors. Inhibitory postsynaptic potentials were mediated by GABA(A) or glycinergic receptors. Although most responses occurred at relatively long latencies (> 2 ms), they could follow relatively high-frequency stimulation (> 50 Hz). Excitatory and inhibitory connections between ipsi- and contralateral nPontc neurones were also documented, which could contribute to bilateral coordination of jaw movements. This study provides evidence that the nPontc exerts both tonic and phasic influences on the premotor components of the masticatory central pattern generator.
Dal Bo
G
G
Centre de Recherche en Sciences Neurologiques, Université de Montréal, Pavillon Paul-G. Desmarais, C.P. 6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7, Canada.
Lund
J P
JP
Verdier
D
D
Kolta
A
A
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000367:Age Factors; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009434:Neural Pathways / Q000166:cytology* / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D011149:Pons / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects; D013681:Tegmentum Mesencephali / Q000033:anatomy & histology* / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology
D000779:Anesthetics, Local; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D011810:Quinoxalines; D013779:Tetrodotoxin; C056723:FG 9041; C013411:biocytin; D008239:Lysine; D001640:Bicuculline