OBJECTIVETo investigate the effects of intrathecal ouabain and tizanidine injection for treatment of neuropathic pain in rats.

METHODSMale SD rats weighing 250-300 g were randomly divided into 5 groups (n = 6), namely the control group, ouabain group, tizanidine group, combined ouabain and tizanidine injection group, and the antagonist group. Intrathecal catheter was implanted 7 days before spinal nerve ligation to establish the neuropathic pain model. Mechanical withdrawal threshold (MWT) before and after intrathecal administration of the agents was recorded in the rats. Isobolographic analysis was performed to evaluate the interactions between the agents.

RESULTSIntrathecal injection of ouabain (0.25-5 microg) or tizanidine (0.5-5 microg) alone produced dose-dependent analgesic effect against the neuropathic pain (P < 0.05). Isobolographic analysis revealed a synergistic interaction between ouabain and tizanidine. Intrathecal pretreatment with atropine (5 microg) or yohimbine (20 microg) antagonized the effects of ouabain and tizanidine administered alone or in combination (P < 0.05).

CONCLUSIONIntathecal injection of ouabain or tizanidine produces dose-dependent analgesic effects against neuropathic pain, and their synergistic effect after combined injection probably involves the cholinergic transmission and alpha2 receptor.

Analgesics ; administration & dosage ; Animals ; Clonidine ; administration & dosage ; analogs & derivatives ; Injections, Spinal ; Ouabain ; administration & dosage ; Pain ; drug therapy ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Spinal Nerves ; injuries

OBJECTIVETo investigate the interactive effect of job task and psychosocial factors on the outcomes of musculoskeletal disorders.

METHODS653 workers from different type of manufacturing industries and administration office recruited in a cross-sectional epidemiological survey. The Quick Exposure Check (QEC) was applied to assess the ergonomic load of job task, Job Content Questionnaire (JCQ) for identifying psychological characteristics, and Nordic Standardized Questionnaire for investigating outcomes of WMSDs.

RESULTSThe prevalence of WMSD in shoulder, upper back, lower back and hand/wrist were significantly different under a variety of combined job task and psychosocial characteristics (P < 0.05 or P < 0.01). The more physical and psychological loads, the higher prevalence of WMSDs were revealed. By using multivariate analyses, a potential interactive effect was found in terms of the WMSDs symptoms in hand/wrist, shoulder, upper back and lower back after adjusted by work year, age, and gender.

CONCLUSIONSHigher physical load and greater psychosocial risk are more frequent self-reported symptoms of WMSDs than those of lower exposures. Ergonomic intervention strategies aimed at reducing the incidence of WMSDs should not only be focused on control of physical work factors but also psychosocial risks of relevance.

Adolescent ; Adult ; Female ; Humans ; Male ; Middle Aged ; Musculoskeletal Diseases ; etiology ; psychology ; Occupational Diseases ; etiology ; psychology ; Stress, Psychological ; Surveys and Questionnaires ; Task Performance and Analysis ; Young Adult