Intrathecal NGF administration reduces reactive astrocytosis and changes neurotrophin receptors expression pattern in a rat model of neuropathic pain.
Nerve growth factor (NGF), an essential peptide for sensory neurons, seems to have opposite effects when administered peripherally or directly to the central nervous system. We investigated the effects of 7-days intrathecal (i.t.) infusion of NGF on neuronal and glial spinal markers relevant to neuropathic behavior induced by chronic constriction injury (CCI) of the sciatic nerve. Allodynic and hyperalgesic behaviors were investigated by Von Frey and thermal Plantar tests, respectively. NGF-treated animals showed reduced allodynia and thermal hyperalgesia, compared to control animals. We evaluated on lumbar spinal cord the expression of microglial (ED-1), astrocytic (GFAP and S-100beta), and C- and Adelta-fibers (SubP, IB-4 and Cb) markers. I.t. NGF treatment reduced reactive astrocytosis and the density of SubP, IB4 and Cb positive fibers in the dorsal horn of injured animals. Morphometric parameters of proximal sciatic nerve stump fibers and cells in DRG were also analyzed in CCI rats: myelin thickness was reduced and DRG neurons and satellite cells appeared hypertrophic. I.t. NGF treatment showed a beneficial effect in reversing these molecular and morphological alterations. Finally, we analyzed by immunohistochemistry the expression pattern of neurotrophin receptors TrkA, pTrkA, TrkB and p75(NTR). Substantial alterations in neurotrophin receptors expression were observed in the spinal cord of CCI and NGF-treated animals. Our results indicate that i.t. NGF administration reverses the neuro-glial morphomolecular changes occurring in neuropathic animals paralleled by alterations in neurotrophin receptors ratio, and suggest that NGF is effective in restoring homeostatic conditions in the spinal cord and maintaining analgesia in neuropathic pain.
Cirillo
Giovanni
G
Laboratorio di Morfologia delle Reti Neuronali, Dipartimento di Medicina Pubblica Clinica e Preventiva, Seconda Università di Napoli, 80138, Naples, Italy.
Cavaliere
Carlo
C
Bianco
Maria Rosaria
MR
De Simone
Antonietta
A
Colangelo
Anna Maria
AM
Sellitti
Stefania
S
Alberghina
Lilia
L
Papa
Michele
M
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002452:Cell Count; D003251:Constriction, Pathologic; D004195:Disease Models, Animal; D005727:Ganglia, Spinal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005911:Gliosis / Q000378:metabolism / Q000473:pathology*; D007150:Immunohistochemistry; D007278:Injections, Spinal; D008297:Male; D009186:Myelin Sheath / Q000187:drug effects / Q000473:pathology; D020932:Nerve Growth Factor / Q000008:administration & dosage* / Q000494:pharmacology*; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D010146:Pain / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism*; D012584:Sciatic Nerve / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D015415:Biomarkers; D017475:Receptors, Nerve Growth Factor; D020932:Nerve Growth Factor