[The role of substance P in the modulation of myotension in paralyzed limbs after spinal transsection on rats].
It is a common clinical observation that stretch reflex excitability increases progressively after spinal transsection in man, and causes many severe complications. The purpose of the present study was to investigate the role and mechanism of substance P (SP) on the spinal reflex following spinal cord transsection. We first observed the changes of spontaneous electromyography (EMG) recorded in the paralyzed limbs of spinally transsected rats, and found that the EMG amplitude increased progressively within 40 days. The results were as follows: 1) Spontaneous EMG increased significantly following intrathecal injection of 1 microgram capsaicin, and the sensitivity of EMG to capsaicin increased progressively with time. But this effect could be partly blocked by pretreatment with SP antiserum. 2) Spontaneous EMG increased significantly following intrathecal injection of SP. Yet the time course was relatively short and the amplitude of EMG was lower. These results indicate that SP in the spinal dorsal horn participates in the regulation of myotension, and it is suggested that to decrease SP content in the spinal dorsal horn or block the afferent fibers of dorsal roots might be an effective therapy to reduce the hypermyotension caused by spinal cord injury, multiple sclerosis or other reasons.
Zhang
J
J
PUMC, Beijing.
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004576:Electromyography / Q000187:drug effects; D005260:Female; D007278:Injections, Spinal; D009122:Muscle Hypertonia / Q000209:etiology / Q000503:physiopathology*; D009129:Muscle Tonus / Q000187:drug effects; D010264:Paraplegia / Q000209:etiology / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D013119:Spinal Cord Injuries / Q000150:complications*; D013373:Substance P / Q000494:pharmacology / Q000502:physiology*
D013373:Substance P; D002211:Capsaicin