Influence of temporomandibular joint pain on sleep patterns: Role of nitric oxide

Abstract

Since nitric oxide is related to nociception and the sleep- wake cycle, this study sought to determine its involvement in the altered sleep pattern in a temporomandibular joint pain model by investigating the effect of the inhibitor of nitric oxide synthase ( L- NAME) and that of its precursor ( L- arginine). The temporomandibular joints of test animals were injected with Freund's adjuvant or saline, and their sleep was recorded. The procedure was repeated after the administration of L- NAME and L- arginine. L-NAME increased rapid eye movement ( REM) sleep in the control group. The orofacial pain group showed a reduction in total sleep time and an increase in sleep latency compared with the SHAM group. L- NAME increased sleep time, non- rapid eye movement ( NREM), and REM sleep and reduced sleep latency in the orofacial pain group. L- arginine did not alter sleep parameters. Thus, L- NAME improved sleep efficiency, whereas L- arginine did not modify it, suggesting the involvement of nitric oxide in painful temporomandibular joint conditions.