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The cause of pain following rotator cuff tear has not been fully elucidated. The purpose of this study was to evaluate behavior and inflammatory cytokines in a rat unstabilized rotator cuff defect (UCD) model. Forty-five Sprague-Dawley rats were divided into three groups: sham; UCD; and stabilized rotator cuff defect (SCD). Gait analysis was examined using CatWalk. Tumor necrosis factor (TNF)-a, interleukin(IL)-1b, and IL-6 were measured within the subacromial bursa and the glenohumeral joint synovium at 21 and 56 days after surgery using an enzyme-linked immunosorbent assay (ELISA). Stride length, print area and contact intensity in the UCD group was significantly lower than in the sham group after surgery. Stride length, print area and contact intensity in the SCD group was significantly higher than in the UCD group. In contrast, TNF-a, IL-1b, and IL-6 in the UCD group was significantly higher than in the sham group at days 21 and 56. However, TNF-a, IL-1b, and IL-6 in the SCD group was significantly lower than in the UCD group at days 21 and 56. The present results suggest that SCD is effective not only in improving shoulder function but also in reducing inflammatory cytokines, which may serve as one source of pain due to rotator cuff tear. ß

This study evaluated dorsal root ganglia from C3-C7, analyzed gait, and compared the expression of calcitonin generelated peptide (CGRP) which was a marker of inflammatory pain in a rat rotator cuff tear model in which the supraspinatus and infraspinatus tendons were detached; comparisons were made to a sham group in which only the tendons were exposed. Fluorogold was injected into the glenohumeral joint 21 days after surgery in both groups, and saline, steroids, or hyaluronic acid was injected into the glenohumeral joint in the rotator cuff tear group 26 days after surgery. The proportions of CGRP-immunoreactive neurons were higher and the gait parameters were impaired in the rotator cuff tear group compared to in the sham group. However, the CGRP expression was reduced and the gait was improved with steroid or hyaluronic acid injection compared to saline, suggesting that both hyaluronic acid and steroid injections suppressed of inflammation which thought to be provided pain relief. While there were no significant differences, the suppression of CGRP expression and the improved gait after hyaluronic acid and steroid injections suggested that both methods were effective for rat rotator cuff tear model. Keywords: rotator cuff tear model; pain relief; hyaluronic acid; dorsal root ganglion; CatWalkThe main symptoms of a rotator cuff tear (RCT) are shoulder pain and limited range of motion. Conservative treatment for RCT consists of medication, fomentation, or injections into the subacromial bursa (SAB) or glenohumeral joint (GHJ). In addition, physical rehabilitation has also been used. Although both steroid 1-3 and hyaluronic acid (HA) injections have been commonly used as a conservative treatment for RCT, it remains unknown which method is more effective for pain relief 2,4-6 Moreover, repeated steroid injections may result in local tissue degradation, including tendon tearing and steroid arthropathy. 1 Although the cause of pain in shoulder pathology has not been fully clarified, calcitonin gene-related peptide (CGRP) was found to be highly expressed in both the GHJ and SAB in a rat contracture shoulder model. These results indicate that up-regulation of CGRP might be closely related to the cause of pain in frozen shoulder; 7 the same mechanism of up-regulation of CGRP has also been hypothesized to be related to RCT of inflammatory pain. For both the GHJ and SAB, sensory information is transmitted from free nerve endings through the dorsal root ganglia (DRG) at C3-C7 to the spinal cord and brain. 8 For investigation of inflammation-related pain, evaluation at the level of the DRG is important especially the expression of CGRP.The purpose of the present study was (i) to evaluate DRG neurons innervating the GHJ and SAB using immunohistochemistry for CGRP in a rat RCT model and (ii) to determine whether steroid or HA injection would provide more effective in rotator cuff tear model. MATERIALS AND METHODSAll animal protocols were approved by the Ethics Committee of Chiba University and conducted in accorda...

We have previously shown that long-term exposure to medium containing insulin-induced hypoglycemic serum during the early phase of organogenesis can adversely affect embryonic development in rat embryo culture and that these effects were mediated through the interruption of glycolytic flux that constituted the principal pathway at this embryonic stage. Further experiments were performed to examine whether brief exposure to the hypoglycemic medium during critical developmental periods would have adverse effects on embryogenesis during embryo culture not only in normal but also in high glucose concentrations. Rat embryos in the early head-fold stage (9.5 days gestation) were grown in vitro for 48 h until neural tube closure occurred; dysmorphogenic lesions were not elicited in either the basal culture medium containing 6.6 mM glucose (control medium) or the hyperglycemic medium supplemented with glucose at a concentration of 33.3 mM. Hypoglycemic mediums (2.2-2.5 mM glucose) were prepared from the serum of rats given insulin intraperitoneally. Postimplantation embryos (in early neural tube formation) were briefly exposed (1 h) to hypoglycemic medium on day 10.3 of gestation during the basal culture. After exposure to the hypoglycemic medium for 1 h during culture in the control medium, embryos showed minor growth retardation and dysmorphogenic lesions (7.1% open neural pores). Exposure to the hypoglycemic medium for 1 h during culture in hyperglycemic medium suplemented with a subteratogenic concentration of glucose (33.3 mM) resulted in greater growth retardation and increased occurrence of dysmorphogenic lesions (17.3% open neural pores).(ABSTRACT TRUNCATED AT 250 WORDS)