Magnesium Sulfate Reduces Carrageenan-Induced Rat Paw Inflammatory Edema Via Nitric Oxide Production

Background

Magnesium is an antagonist of the N-methyl-D-aspartate receptor. This study aimed to investigate the anti-edematous effect of magnesium sulfate (MS) in different protocols of use and the possible mechanism of its action.

Methods

In a rat model of carrageenan-induced paw inflammation, the anti-edematous activity of MS was assessed with a plethysmometer. The effects of the nonselective inhibitor (L-NAME), selective inhibitor of neuronal (L-NPA) and inducible (SMT) nitric oxide synthase on the effects of MS were evaluated.

Results

MS administered systemically before or after inflammation reduced edema by 30% (5 mg/kg, P < .05) and 55% (30 mg/kg, P < .05). MS administered locally (.5 mg/paw, P < .05) significantly prevented the development of inflammatory edema by 60%. L-NAME, intraperitoneally administered before MS, potentiated (5 mg/kg, P < .05) or reduced (3 mg/kg, P < .05), while in the highest tested dose L-NPA (2 mg/kg, P < .01) and SMT (.015 mg/kg, P < .01) reduced the anti-edematous effect of MS.

Conclusions

Magnesium is a more effective anti-edematous drug in therapy than for preventing inflammatory edema. The effect of MS is achieved after systemic and local peripheral administration and when MS is administered as a single drug in a single dose. This effect is mediated at least in part via the production of nitric oxide.

Chloroquine Attenuates Oxidative Stress in Gentamicin-Induced Nephrotoxicity in Rats

The wider application of gentamicin is limited by potential adverse effects (nephrotoxicity and ototoxicity). The goal of our study was to investigate the effects of chloroquine on biochemical and oxidative stress parameters in gentamicin-induced nephrotoxicity in rats. Animals were randomly divided into 1 of 5 groups. First was Sham group (0.9% NaCl) (n = 8); second group received gentamicin (n = 8); while third (n = 8), fourth (n = 8) and fifth group (n = 8) received gentamicin and chloroquine in a dose of 0.3, 1 and 3 mg/kg, respectively. The urea and creatinine levels were significantly lower in chloroquine treated groups in doses of 0.3 mg/kg and 1 mg/kg (P < 0.001). Total oxidant status and the oxidative stress index showed significantly lower values in all chloroquine treated groups (P < 0.001; P < 0.005). Malondialdehyde was lower in chloroquine treatment in doses of 0.3 mg/kg (P < 0.005) and 3 mg/kg (P < 0.05). Chloroquine treatment markedly reduced the level of superoxide dismutase in doses of 1 mg/kg (P < 0.01) and 3 mg/kg (P < 0.05). Our study showed that chloroquine attenuates gentamicin-induced nephrotoxicity in rats regarding biochemical and oxidative stress parameters.

Investigation of the Antinociceptive Activity of the Hydroethanolic Extract of Junglas nigra Leaf by the Tail-Immersion and Formalin Pain Tests in Rats

Background

Juglans (J.) nigra leaf is obtained from a plant that is used in traditional medicine in some countries to alleviate inflammatory diseases.

Aim

The aim of this study was to compare the effects of J. nigra extract on acute nociceptive and inflammatory pain in rats.

Methods

Antinociceptive activity was examined in Wistar rats by the tail-immersion and formalin tests. Motor function was assessed using the rotarod test. Plant extract was administered intraperitoneally.

Results

In the tail-immersion test, the maximal antinociceptive effect of the plant extract (100–330 mg/kg) was about 24–30% and is the result of the effect of a high concentration of ethanol. In the formalin test, the plant extract (41.3–330 mg/kg) significantly and dose-dependently inhibited nociception in both phases of the test with similar maximal effects of about 76% and 85%. Only the plant extract at the dose of 330 mg/kg caused a significant time-dependent reduction in time spent on the rotarod.

Conclusions

In rats, the preventive systemic administration of the hydroethanolic extract of J. nigra leaf reduced chemically but not thermally induced pain. Higher efficacy was obtained in pain associated with inflammation and tissue injury. The antinociceptive effect is dose-dependent and may be limited by motor impairment.

The Interactions of Magnesium Sulfate and Cromoglycate in a Rat Model of Orofacial Pain; The Role of Magnesium on Mast Cell Degranulation in Neuroinflammation

Mast cell degranulation impacts the development of pain and inflammation during tissue injury. We investigated the antinociceptive effect of a combination of cromoglycate and magnesium in the orofacial model of pain and the histological profile of the effect of magnesium in orofacial pain. In male Wistar rats, formalin (1.5%, 100 µL) was injected subcutaneously into the right upper lip of rats after cromoglycate and/or magnesium. Pain was measured as the total time spent on pain-related behavior. Toluidine blue staining was used to visualize mast cells under the light microscope. In the formalin test, in phase 1, magnesium antagonized the antinociceptive effect of cromoglycate, while in phase 2, it potentiated or inhibited its effect. Magnesium significantly reduced mast cell degranulation in the acute phase by about 23% and in the second phase by about 40%. Pearson’s coefficient did not show a significant correlation between mast cell degranulation and pain under treatment with magnesium. The cromoglycate–magnesium sulfate combination may prevent the development of inflammatory orofacial pain. The effect of a combination of cromoglycate–magnesium sulfate depends on the nature of the pain and the individual effects of the drugs. Magnesium reduced orofacial inflammation in the periphery, and this effect did not significantly contribute to its analgesic effect.