Clinically, chemical inhibition of the PNS is used to manage joint pain. Chemical blockade of the sympathetic nervous system is often accomplished through the administration of guanethidine. Guanethidine blocks the release and subsequent reuptake of norepinephrine (NE) (a major sympathetic neurotransmitter) in patients with osteoarthritis, rheumatoid arthritis, and reflex sympathetic dystrophy (12, 13, 24, 38, 40). This treatment, while effective in relieving pain, may have undesirable effects on connective tissues, because it alters the normal concentration of neurogenic factors.
Growing anatomic and physiological evidence suggest that the PNS is important to ligament and joint homeostasis.Denervation of peripheral nerves leads to decreased healing of the MCL and promotes the onset of osteoarthritis (22, 34). Partial injury to the MCL can lead to increases in vascular volume, a factor that is largely controlled by ligament innervation (7). During periods of chronic overuse or disuse, homeostatic changes can be detrimental to the structural integrity of ligaments. Although the above evidence suggests that peripheral nerves play an essential role in ligament homeostasis, few studies exist that directly investigate this role.
J Appl Physiol 96: 711-718, 2004