Patterns of FOS expression in the spinal cord and periaqueductal grey matter of 6OHDA-lesioned rats.
A less well-known feature of Parkinson disease is that up to 40% of patients experience distinct sensory disturbances, including hyperalgesia and chronic pain. There is a limited understanding of the neural mechanisms that generate these symptoms, however. This study explores the patterns of Fos expression (a well-known marker for changes in cell activity) in the spinal cord and periaqueductal grey matter (PaG), two major sensory (nociceptive) centers, of hemiParkinsonian rats. The medial forebrain bundle (mfb; major tract carrying dopaminergic nigrostriatal axons) was injected with either 6OHDA or saline (controls). A week later, some rats were subjected to mechanical stimulation (pinching) of the hindpaw for 2 h, whereas others received no stimulation. Thereafter, brains were processed using routine tyrosine hydroxylase (marker for dopaminergic cells) or Fos immunocytochemistry. In the PaG, there were many more Fos(+) cells in the 6OHDA-lesioned than in the Control group, in both the stimulation and, in particular, the non-stimulation cases. In the spinal cord, there were also more Fos(+) cells in the 6OHDA-lesioned than in the Control group, but in the stimulation cases only. Overall, the results show distinct changes in Fos expression in the spinal cord and PaG of 6OHDA-lesioned rats, suggesting a substrate for some of the abnormal sensory (nociceptive) circuits that may be evident in parkinsonian cases.
Reyes
Stephanie
S
Department Anatomy and Histology, University of Sydney, Sydney, Australia.
Mitrofanis
John
J
D000818:Animals; D004195:Disease Models, Animal; D007839:Functional Laterality / Q000502:physiology; D007150:Immunohistochemistry; D008159:Lumbar Vertebrae; D008297:Male; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000201:enzymology; D009619:Nociceptors / Q000378:metabolism; D016627:Oxidopamine; D020734:Parkinsonian Disorders / Q000139:chemically induced / Q000150:complications / Q000378:metabolism*; D010487:Periaqueductal Gray / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012678:Sensation Disorders / Q000150:complications / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*; D013378:Substantia Nigra / Q000166:cytology / Q000378:metabolism; D014018:Tissue Distribution; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D016760:Proto-Oncogene Proteins c-fos; D016627:Oxidopamine; D014446:Tyrosine 3-Monooxygenase