Decreased pain response in mice following cortex-specific knockout of the N-methyl-D-aspartate NR1 subunit.
Studies have shown that N-methyl-D-aspartate (NMDA) receptors play a critical role in pain processing at different levels of the central nervous system. In this study, we used cortex-specific NR1 knockout mice (C57BL/6 strain) to elucidate the role of cortical NMDA receptors in pain processes. On post-natal day 20, paw withdrawal latency (PWL) to a noxious thermal stimulus was measured in male and female knockout (KO), control (Ctrl), and C57BL/6 (C57) mice. Twenty-four hours later, the same mice were tested in the formalin-pain assay (20 microl of 5% formalin injected into one hind-paw). The results show that KO mice (both male and female) have significantly reduced pain responses during both early and late phases of formalin test, as compared with Ctrl and C57 mice (p<0.01). By contrast, no differences among groups were found in PWL to a noxious thermal stimulus. Taken together, these results demonstrate dissociation in the role of cortical NMDA receptors in mediating different types of pain.
Quintero
Gabriel C
GC
Neuroscience Center of Excellence, Louisiana State University Health Science Center, New Orleans, LA 70112, USA. gquinter@uno.edu
Erzurumlu
Reha S
RS
Vaccarino
Anthony L
AL
D000344:Afferent Pathways / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism / Q000503:physiopathology*; D004195:Disease Models, Animal; D015536:Down-Regulation; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D006930:Hyperalgesia / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009619:Nociceptors / Q000502:physiology; D010146:Pain / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D011930:Reaction Time / Q000235:genetics; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics*; D012727:Sex Characteristics; D009435:Synaptic Transmission / Q000235:genetics