Chronic low back pain is a major cause of disability and health care costs. Current treatments are inadequate for\r\nmany patients. A number of preclinical models have been developed that attempt to mimic aspects of clinical\r\nconditions that contribute to low back pain. These involve application of nucleus pulposus material near the\r\nlumbar dorsal root ganglia (DRG), chronic compression of the DRG, or localized inflammation of the DRG. These\r\nmodels, which are primarily implemented in rats, have many common features including behavioral hypersensitivity\r\nof the hindpaw, enhanced excitability and spontaneous activity of sensory neurons, and locally elevated levels of\r\ninflammatory mediators including cytokines. Clinically, epidural injection of steroids (glucocorticoids) is commonly\r\nused when more conservative treatments fail, but clinical trials evaluating these treatments have yielded mixed\r\nresults. There are relatively few preclinical studies of steroid effects in low back pain models. One preclinical study\r\nsuggests that the mineralocorticoid receptor, also present in the DRG, may have pro-inflammatory effects that\r\noppose the activation of the glucocorticoid receptor. Although the glucocorticoid receptor is the target of\r\nanti-inflammatory steroids, many clinically used steroids activate both receptors. This could be one explanation\r\nfor the limited effects of epidural steroids in some patients. Additional preclinical research is needed to address\r\nother possible reasons for limited efficacy of steroids, such as central sensitization or presence of an ongoing\r\ninflammatory stimulus in some forms of low back pain.
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