Supraspinal descending pathways from the periaqueductal gray and rostral ventromedial medulla dynamically modulate nociceptive transmission in the spinal dorsal horn. We examined the expression of the brain-derived neurotrophic factor receptor trkB in response to inflammation. No difference was observed in the number of neurons expressing trkB in the periaqueductal gray or rostral ventromedial medulla 3 h after inflammation; however, by 24 h, there was a significant increase in trkB expression in the periaqueductal gray (P < 0.05) and rostral ventromedial medulla (P < 0.05), compared with naïve levels, which persisted to 7 days and returned to naïve levels by 21 days. These results demonstrate a temporal increase in the number of cells expressing trkB in response to persistent inflammation, suggesting a role for trkB signaling in activity-dependent plasticity in the pain modulatory circuitry.
Neuroreport 07/2006; 17(11):1175-9. DOI:10.1097/01.wnr.0000215771.61355.e1 · 1.64 Impact Factor