Association between naturally occurring spine osteoarthritis in geriatric rats and neurogenic inflammation within neurosegmentally linked skeletal muscle

• Published in: Experimental gerontology Vol. 118; pp. 31 - 38
• Main Authors: Duarte, Felipe C.K., Hurtig, Mark, Clark, Andrea, Simpson, Jeremy, Srbely, John Z.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.04.2019
• Subjects: Central sensitization; Myofascial pain syndrome; Neurogenic inflammation; Osteoarthritis; Substance P; Central sensitization; Myofascial pain syndrome; Neurogenic inflammation; Substance P; Osteoarthritis
• ISSN: 0531-5565; 1873-6815
• DOI: 10.1016/j.exger.2019.01.002

This study aimed to investigate the association between naturally occurring spinal osteoarthritis (OA) (L3-L5), the expression of substance P (SP) centrally (L4-L5) and the presence of neurogenic inflammation within the neurosegmentally linked quadriceps (L2-L5) in elderly rats versus young controls. Eight aged (27 ± 3.2 months) and six young (4 ± 0.0 months) male Wistar Kyoto rats were euthanized and submitted to micro-computerized tomography for determination of spine OA. SP expression (% area) at the dorsal horn of the spinal cord as well as the relative expression of SP and protease-activated receptor 2 (PAR2) to alpha-tubulin within quadriceps muscle were determined by immunohistochemistry and Western Blot. Spine osteoarthritis was confirmed in all aged rats but no young controls. Aged rats expressed significant increase of SP protein expression within the dorsal horn (MD = 0.086; 95% CI [0.026 to 0.145]; p = 0.0094) and quadriceps (MD = 1.209; 95% CI [0.239 to 2.179]; p = 0.0191) and PAR2 (MD = 0.797; 95% CI [0.160 to 1.435]; p = 0.0187) compared to young controls. These observations provide novel insight into the potential role of neurogenic inflammation in the pathophysiology of myofascial pain syndrome in the naturally occurring spinal OA in elderly population. •Aging rats with spine osteoarthritis have higher SP immunoreactivity in the lumbar spinal cord.•Aging rats with spine osteoarthritis present higher expression of SP within quadriceps muscle.•Aging rats with spine osteoarthritis present higher expression of PAR2 within quadriceps muscle.•Spinal osteoarthritis may be a common primary pathology driving neurogenic inflammation in muscle.•Spinal osteoarthritis may be an important driver of myofascial pain syndrome in elderly population.