Synaptic relationships between induced neuropeptide Y-like immunoreactive terminals and cuneothalamic projection neurons in the rat cuneate nucleus following median nerve transection.
Previous studies have demonstrated that following complete median nerve transection (CMNT), neuropeptide Y-like immunoreactive (NPY-LI) fibers were dramatically increased and predominantly expressed in the ventral portion of the middle cuneate nucleus (CN), reaching maximum numbers at four weeks. Ultrastructurally, NPY-LI terminals made axodendritic synapses, but the postsynaptic elements are unknown. In the present study, using retrograde tract-tracing of wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) and NPY immunocytochemistry we examined the synaptic relationships between cuneothalamic projection neurons (CTNs) and NPY-LI terminals in the rat CN following CMNT. The injury-induced NPY-LI fibers were distributed throughout the rostrocaudal extent of the CN. Further, the greatest number of HRP-labeled CTNs was observed in the ventral portion of the middle CN. Ultrastructurally, the NPY-LI terminals made asymmetric axodendritic synaptic contact with the HRP-labeling CTN dendrites. These data suggest that injury-induced NPY may modulate the excitability of CTNs, and thus, play a role in the transmission of neuropathic sensation following median nerve injury.
Yeh
Jiann-Horng
JH
Department of Neurology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan, ROC.
Lue
June-Horng
JH
Wang
Hsin-Ying
HY
Huang
Chun-Ta
CT
Tsai
Yi-Ju
YJ
D000818:Animals; D019771:Axotomy; D007150:Immunohistochemistry; D008297:Male; D008475:Median Nerve / Q000502:physiology; D008526:Medulla Oblongata / Q000378:metabolism / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D009434:Neural Pathways / Q000378:metabolism / Q000648:ultrastructure*; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure*; D009478:Neuropeptide Y / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure*
D009478:Neuropeptide Y