Expression of p-Akt in sensory neurons and spinal cord after peripheral nerve injury.
Akt has been implicated in pro-survival and anti-apoptotic activities in many cell types, including dorsal root ganglion (DRG) and spinal motor neurons. In this immunohistochemical study we have monitored phosphorylated Akt (p-Akt) levels in adult mouse DRGs and spinal cord following unilateral peripheral sciatic nerve transection (axotomy) or carrageenan-induced inflammation. In control animals around half of the lumbar DRG neuron profiles (NPs), mainly small and medium-sized ones, were p-Akt immunoreactive (IR), and of these around 50% expressed calcitonin gene-related peptide and/or isolectin IB4. Two weeks after axotomy, the number of p-Akt-positive NPs was only slightly reduced, but p-Akt immunofluorescence intensity was strongly increased. One third of the ipsilateral p-Akt-IR NPs was galanin positive, but virtually without colocalization with neuropeptide Y. Furthermore, p-Akt-like immunoreactivity significantly increased in intensity in the ipsilateral spinal dorsal horn after axotomy and expanded into deeper layers. Carrageenan-induced peripheral inflammation increased the number of p-Akt-IR NPs after 1 h. Both axotomy and inflammation caused a clear increase in nuclear p-Akt-like immunoreactivity in DRG neurons. Our findings support a role for Akt as a key signaling molecule in sensory neurons and spinal cord after peripheral injury.
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden. tiejun.shi@ki.se
Tie-Jun Sten
TJ
Shi
Ping
P
Huang
Jan
J
Mulder
Sandra
S
Ceccatelli
Tomas
T
Hokfelt
D000818:Animals; D019771:Axotomy; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D048429:Cell Size; D019004:Galanin / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000494:pharmacology; D008159:Lumbar Vertebrae; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009437:Neuralgia / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012584:Sciatic Nerve / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D020426:Sciatic Neuropathy / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D011984:Sensory Receptor Cells / Q000166:cytology / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*
D018836:Inflammation Mediators; D019004:Galanin; D051057:Proto-Oncogene Proteins c-akt; D015740:Calcitonin Gene-Related Peptide