Capsaicin attenuates excitotoxic-induced neonatal brain injury and brain mast cell-mediated neuroinflammation in newborn rats.

Excitotoxicity and neuroinflammation are key contributors to perinatal brain injuries. Capsaicin, an active ingredient of chili peppers, is a potent exogenous agonist for transient receptor potential vanilloid 1 receptors. Although the neuroprotective and anti-inflammatory effects of capsaicin are well-documented, its effects on excitotoxic-induced neonatal brain injury and neuroinflammation have not previously been investigated. The aim of this study was to investigate the effects of capsaicin on brain damage, brain mast cells, and inflammatory mediators in a model of ibotenate-induced excitotoxic brain injury in neonatal rats. P5 rat-pups were intraperitoneally injected with vehicle, 0.2-, 1-, and 5-mg/kg doses of capsaicin, or the NMDA (N-methyl-d-aspartate) receptor antagonist MK-801 (dizocilpine), 30 min before intracerebral injection of 10 µg ibotenate. The naive-control group received no substance administration. The rat pups were sacrificed one or five days after ibotenate injection. Levels of activin A and interleukin (IL)-1ß, IL-6, and IL-10 in brain tissue were measured using the enzyme-linked immunosorbent assay method. Cortex and white matter thicknesses, white matter lesion size, and mast cells were evaluated in brain sections stained with cresyl-violet or toluidine-blue. Capsaicin improved ibotenate-induced white matter lesions and cerebral white and gray matter thicknesses in a dose-dependent manner. In addition, it suppressed the degranulation and increased number of brain mast cells induced by ibotenate. Capsaicin also reduced the excitotoxic-induced production of neuronal survival factor activin A and of the pro-inflammatory cytokines IL-1ß, and IL-6 in brain tissue. However, IL-10 levels were not altered by the treatments. MK-801, as a positive control, reversed all these ibotenate-induced changes, further confirming the success of the model. Our findings provide, for the first time, evidence for the therapeutic effects of capsaicin against excitotoxic-induced neonatal brain injury and brain mast cell-mediated neuroinflammation. Capsaicin may therefore be a promising candidate in the prevention and/or reduction of neonatal brain damage.

Does methylene blue reduce adhesion during the healing process after tendon repair?

OBJECTIVES: This study aims to biomechanically and histopathologically investigate the effects of methylene blue (MB) on preventing postoperative adhesion in chickens undergoing full- thickness flexor tendon incision. MATERIALS AND METHODS: This study was performed between June 2017 and June 2018 on Hubbard JA 57 type chickens (age, 6 months; weight, 2.2±0.3 kg). Sixty-four tendons were studied in 32 chickens, including 16 in the control group and 16 in the experimental group. The second and third finger flexor digitorum profundus tendons of the left foot of each chicken were repaired primarily after a full-thickness incision approximately 1 cm proximal to the distal adhesion area. In the control (n=32) and experimental groups (n=32), 0.25 mL of normal saline and 0.25 mL of 1% MB solutions were applied locally to the surgical site, respectively. The operated limb was immobilized using a circular cast. 16 chickens were randomly selected in each group and examined at the fourth week, and the remaining 16 chickens were examined at the sixth week. Thirty-two of these tendons were evaluated using the Tang histopathological adhesion classification system, and the other 32 were evaluated with a biomechanical pull system. RESULTS: Adhesion was found to be less in the experimental group compared to the control group at the end of the fourth and sixth weeks both histopathologically and biomechanically. Furthermore, adhesion was significantly less in the experimental group at the end of the sixth week compared to the fourth week both histopathologically and biomechanically. CONCLUSION: Histopathological and biomechanical results show that MB, which has anti-inflammatory, antiseptic, antimicrobial and antioxidant effects, reduces adhesion during the healing process after tendon repair. We think that local MB application, particularly in surgeries performed after this type of injury, will be beneficial on early rehabilitation and functional results.