Analgesic Drugs Alter Connective Tissue Remodeling and Mechanical Properties

Comparative Assessment of Short-Term Tendon-Scleral Postoperative Inflammation and α-Smooth Muscle Actin Expression following Oral and Topical Diclofenac Administration for Strabismus Surgery in Rabbits

PURPOSE

Wound healing and fibrosis modulation are considered pivotal for the long-term outcome of strabismus surgery. Nonsteroidal anti-inflammatory drugs, including diclofenac sodium, are inflammation suppressive drugs that may modulate wound healing, including postoperative inflammation. This study aimed to compare the effect of oral and 0.1% topical diclofenac sodium on short-term inflammation and α-smooth muscle actin (α-SMA) expression at the tendon-scleral attachment site following strabismus surgery in an experimental rabbit model.

METHODS

Superior rectus recession was performed in 12 eyes of six New Zealand rabbits. Rabbits were divided into three groups: oral diclofenac 2 × 5 mg/kg for three days (group A), 0.1% diclofenac sodium eye drops 3 times/day for three days (group B), and controls (group C). On postoperative day 14, enucleation was performed. Macroscopic adhesion score, microscopic adhesion score, percentage of postoperative inflammation area (Masson's trichrome staining), and α-SMA (immunohistochemistry staining) were assessed. Data analysis was performed using a semi-quantitative and quantitative assessment with ImageJ. All groups were compared with reciprocal staining intensity (RSI) values to measure α-SMA expression.

RESULTS

All groups showed no difference in macroscopic (p = 0.13) and microscopic adhesion scores (p = 0.28). The percentage of postoperative inflammation area in group B (12.44% (8.63-18.29)) was significantly lower than group A (26.76% (21.38-37.56) p = 0.03) and group C (27.80% (16.42-36.28), p = 0.04). Comparative RSI analysis found that group B had a significantly lower α-SMA expression than group C (174.08 ± 21.78 vs 212.58 ± 12.06, p = 0.04).

CONCLUSION

The results suggest that compared to oral, the administration of topical diclofenac showed a more significant reduction of short-term postoperative inflammation and α-SMA expression at the tendon-scleral attachment site following strabismus surgery.

Melatonin abolished proinflammatory factor expression and antagonized osteoarthritis progression in vivo

Progressive structural changes in osteoarthritis (OA) involve synovial inflammation and angiogenesis, as well as activation of the proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin (IL)-8, and the angiogenic factor vascular endothelial growth factor (VEGF). The endogenous hormone melatonin (N-acetyl-5-methoxytryptamine) is involved in antioxidative and anti-inflammatory activities, but how it antagonizes OA progression via its specific receptors is unclear. Here, we demonstrate that the MT₁ melatonin receptor, but not the MT₂ receptor, is highly expressed in normal tissue and only minimally in OA tissue. By targeting the MT₁ receptor, melatonin reversed OA-induced pathology and effectively reduced levels of TNF-α, IL-8, and VEGF expression in OA synovial fibroblasts and synovium from rats with severe OA. Interestingly, we found that the anabolic activities of melatonin involved the MT₁ receptor, which upregulated microRNA-185a through the PI3K/Akt and ERK signaling pathways in OA synovial fibroblasts. Our investigation confirms the role of the MT₁ receptor in melatonin-induced anti-catabolic effects in OA disease.

Comparison of metamizole and paracetamol effects on colonic anastomosis and fibroblast activities in Wistar rats

BACKGROUND

Leakage following colorectal anastomosis surgery causes various complications associated with high morbidity and mortality, especially in pediatric patients. It might be caused by the use of non-steroidal anti-inflammatory drugs (NSAIDs) as postoperative analgesics. This study aimed to compare the effect of metamizole and paracetamol on colonic anastomosis and fibroblast activities, including proliferation, migration, and collagen synthesis, in Wistar rats.

METHODS

Rats were divided into control, paracetamol and metamizole groups. The colonic anastomosis was evaluated by determining the integrity of the muscle layers, the formation of granulation tissue, and mucosal anastomosis. Fibroblast activities were analyzed by measuring the proliferation, migration, and collagen synthesis.

RESULTS

Metamizole caused more damage to muscle layer integrity, more inhibition of granulation tissue formation in the anastomosis area and lower mucosal anastomosis compared with paracetamol and control groups. Metamizole had a higher cytotoxic effect than paracetamol, which suppressed the proliferation and migration of fibroblasts. Furthermore, both drugs did not affect the synthesis of collagen.

CONCLUSION

Metamizole shows worse effects on the integrity of muscle layers, inhibition of granulation tissue formation, mucosal anastomosis, fibroblast proliferation, and migration, but not collagen synthesis, than paracetamol in Wistar rat intestines following colonic anastomosis. These findings might indicate that paracetamol is safer than metamizole as analgesic following colonic anastomosis.

Impact of acetaminophen consumption and resistance exercise on extracellular matrix gene expression in human skeletal muscle

Acetaminophen (APAP) given during chronic exercise reduces skeletal muscle collagen and cross-linking in rats. We propose that the effect of APAP on muscle extracellular matrix (ECM) may, in part, be mediated by dysregulation of the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs). The purpose of this study was to evaluate the impact of APAP consumption during acute resistance exercise (RE) on several regulators of the ECM in human skeletal muscle. In a double-blinded, placebo-controlled, randomized crossover design, recreationally active men (n = 8, 25 ± 2 yr) performed two trials of knee extension. Placebo (PLA) or APAP (1,000 mg/6 h) was given for 24 h before and immediately following RE. Vastus lateralis biopsies were taken at baseline and 1 and 3 h post-RE. Quantitative RT-PCR was used to determine differences in mRNA expression. MMP-2, type I collagen, and type III collagen mRNA expression was not altered by exercise or APAP (P > 0.05). When compared with PLA, TIMP-1 expression was lower at 1 h post-RE during APAP conditions but greater than PLA at 3 h post-RE (P < 0.05). MMP-9 expression and protein levels were elevated at 3 h post-RE independent of treatment (P < 0.05). Lysyl oxidase expression was greater at 3 h post-RE during APAP consumption (P < 0.05) compared with PLA. MMP-2 and TIMP-1 protein was not altered by RE or APAP (P > 0.05). Phosphorylation of ERK1/2 and p38-MAPK increased (P < 0.05) with RE but was not influenced by APAP. Our findings do not support our hypothesis and suggest that short-term APAP consumption before RE has a small impact on the measured ECM molecules in human skeletal muscle following acute RE.

Sex-based difference in Achilles peritendinous levels of matrix metalloproteinases and growth factors after acute resistance exercise

Several recent investigations have demonstrated that the ability of various tendons to alter structural and functional properties in response to exercise are muted in women compared with men. We hypothesize that this disparity between men and women may be due to a reduced tendon production of key mediators of tendon extracellular matrix (ECM) remodeling in response to mechanical loading, e.g., exercise. Using microdialysis before and after an acute bout of resistance exercise, we evaluated Achilles peritendinous levels of insulin-like growth factor-1 (IGF-1) and interleukin-6 (IL-6), which have both been shown to increase tendon collagen synthesis. Additionally, the matrix remodeling enzymes matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) were also evaluated. IGF-1 levels were elevated ( P < 0.05) to a similar extent in men and women after 3 h of exercise but remained elevated at 4 h in only women. IL-6 levels were ~4-fold greater after exercise in both men and women ( P < 0.05). MMP-2 levels increased to a similar extent (~2-3-fold) in men and women ( P < 0.05). In contrast, MMP-9 increased with exercise but only in men ( P < 0.05). Last, TIMP-1 levels also increased ( P < 0.05) with exercise in men and women but the increase was more prolonged in women. In conclusion, we observed modest sex differences in tendon release of MMP-9, TIMP-1, and IGF-1 after acute resistance exercise. If such differences persist throughout a chronic exercise training, they may contribute to the reduced ability of women to adapt to exercise compared with men.

NEW & NOTEWORTHY In this investigation we utilized microdialysis of the peritendinous Achilles to evaluate potential differences between men and women in tendon production of key regulators of extracellular matrix remodeling. We demonstrate that a modest sex-specific difference exists in peritendinous levels of several key extracellular matrix modulators after an acute bout of resistance exercise.