Immunohistochemical demonstration of exocytosis-regulating proteins within rat molar dentinal tubules.
No morphologically defined synaptic structures have so far been detected between nerve terminals and the dentine-producing odontoblasts. Recent studies of the molecular mechanisms in neuronal exocytosis have identified several proteins that participate in synaptic-vesicle exocytosis. By localizing these proteins with immunohistochemical methods, information about the capacity for synaptic exocytosis should be obtained. Here, antibodies directed against some of the exocytosis-related proteins were used to investigate whether they are present in nerve fibers within the dentinal tubules in rat molars. Antibodies against synaptosome-associated protein of 25 kDa, Rab 3, synaptotagmin and synapsin all produced a punctuate staining pattern, suggesting that the proteins are accumulated in bouton-like elements. The results demonstrate that a set of exocytosis-related proteins is accumulated in the dentinal tubules, most probably within the intradentinal nerves. This finding is consistent with the hypothesis that intradentinal nerves can mediate efferent signals.
Norlin
T
T
Department of Basic Oral Sciences, Karolinska Institutet, Stockholm, Sweden. thomas.norlin@neuro.ki.se
Hilliges
M
M
Brodin
L
L
D000818:Animals; D002135:Calcium-Binding Proteins; D003782:Dental Pulp / Q000294:innervation* / Q000648:ultrastructure; D003804:Dentin / Q000294:innervation* / Q000648:ultrastructure; D005089:Exocytosis / Q000502:physiology; D019204:GTP-Binding Proteins / Q000032:analysis / Q000502:physiology; D007150:Immunohistochemistry; D008561:Membrane Fusion / Q000502:physiology; D008562:Membrane Glycoproteins / Q000032:analysis / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology; D008963:Molar; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000502:physiology*; D009804:Odontoblasts / Q000502:physiology; D017729:Presynaptic Terminals / Q000737:chemistry / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000737:chemistry / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000502:physiology; D050825:Synaptosomal-Associated Protein 25; D050857:Synaptotagmins; D020692:rab3 GTP-Binding Proteins
D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C079052:SVP-38 protein, rat; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; C032457:exocytosis coupled protein, rat; D050857:Synaptotagmins; D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins