Primary afferent plasticity following deafferentation of the trigeminal brainstem nuclei in the adult rat.
Alpha-tyrosinated tubulin is a cytoskeletal protein that is involved in axonal growth and is considered a marker of neuronal plasticity in adult mammals. In adult rats, unilateral ablation of the left facial sensorimotor cortical areas induces degeneration of corticotrigeminal projections and marked denervation of the contralateral sensory trigeminal nuclei. Western blotting and real-time-PCR of homogenates of the contralateral trigeminal ganglion (TG) revealed consistent overexpression of growth proteins 15 days after left decortication in comparison with the ipsilateral side. Immunohistochemical analyses indicated marked overexpression of alpha-tyrosinated tubulin in the cells of the ganglion on the right side. Cytoskeletal changes were primarily observed in the small ganglionic neurons. Application of HRP-CT, WGA-HRP, and HRP to infraorbital nerves on both sides 15 days after left decortication showed a significant degree of terminal sprouting and neosynaptogenesis from right primary afferents at the level of the right caudalis and interpolaris trigeminal subnuclei. These observations suggest that the adaptive response of TG neurons to central deafferentation, leading to overcrowding and rearrangement of the trigeminal primary afferent terminals on V spinal subnuclei neurons, could represent the anatomical basis for distortion of facial modalities, perceived as allodynia and hyperalgesia, despite nerve integrity.
De Riu
Pier Luigi
PL
Department of Biomedical Science, Human Physiology Division, University of Sassari, Sassari 07100, Italy. fisiou@uniss.it
Russo
Antonella
A
Pellitteri
Rosalia
R
Stanzani
Stefania
S
Tringali
Giovanni
G
Roccazzello
Anna Maria
AM
De Riu
Giacomo
G
Marongiu
Patrizia
P
Mameli
Ombretta
O
D000344:Afferent Pathways / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001931:Brain Mapping; D002422:Causalgia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D003714:Denervation; D005260:Female; D020439:Growth Cones / Q000378:metabolism / Q000648:ultrastructure; D006735:Horseradish Peroxidase; D006930:Hyperalgesia / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009473:Neuronal Plasticity; D009475:Neurons, Afferent / Q000473:pathology / Q000502:physiology*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000473:pathology / Q000503:physiopathology*; D012668:Trigeminal Ganglion / Q000473:pathology / Q000503:physiopathology*; D014278:Trigeminal Nuclei / Q000473:pathology / Q000503:physiopathology*; D014404:Tubulin / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
D015415:Biomarkers; D003598:Cytoskeletal Proteins; D012333:RNA, Messenger; D014404:Tubulin; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D006735:Horseradish Peroxidase