Ultrastructural evidence for an olfactory-autonomic pathway through the rat central amygdaloid nucleus.
The innervation of medullary projection neurons in the central amygdaloid nucleus (Ce) by afferents from the ventral taenia tecta (VTT) was investigated using combined lesion-induced axonal degeneration and retrograde transport of horseradish peroxidase-conjugated wheat germ agglutinin (HRP-WGA). Injections of HRP-WGA into the nucleus tractus solitarii resulted in retrograde labeling of neurons in the medial Ce. Ultrastructurally HRP-WGA reaction product was identifiable in the perikarya and proximal dendrites of Ce neurons. Degenerating terminals, probably due to damage at the HRP-WGA injection site, were few and confined to the ventral Ce. Electrolytic coagulation of the VTT resulted in approximately 9% of terminals in medial Ce showing signs of degeneration at 5 days post-lesion. Of the terminals sampled, slightly more than 40% were in contact with the dendrites of retrogradely labeled neurons. Where evident, these terminals formed exclusively symmetrical synaptic contacts. These data provide evidence for an oligosynaptic olfactory-autonomic pathway in the rat that may mediate olfactory influences on gastric and cardiovascular aspects of autonomic function.
Cassell
M D
MD
Department of Anatomy, University of Iowa, Iowa City 52245.
Roberts
L
L
D000679:Amygdala / Q000648:ultrastructure*; D000818:Animals; D001341:Autonomic Nervous System / Q000648:ultrastructure*; D003712:Dendrites / Q000648:ultrastructure; D006735:Horseradish Peroxidase; D066298:In Vitro Techniques; D008297:Male; D008526:Medulla Oblongata / Q000648:ultrastructure; D009410:Nerve Degeneration / Q000502:physiology; D009474:Neurons / Q000648:ultrastructure; D009833:Olfactory Pathways / Q000648:ultrastructure*; D016548:Prosencephalon / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; D006735:Horseradish Peroxidase