Simvastatin attenuates cardiac isograft ischemia-reperfusion injury by down-regulating CC chemokine receptor-2 expression

Simvastatin prevents morphine antinociceptive tolerance and withdrawal symptoms through antioxidative effect and nitric oxide pathway in mice

Oxidative stress and the nitric oxide (NO) pathway are involved in the development of opioid analgesic tolerance and dependence. Simvastatin modulates NO and oxidative stress, so the present study aimed to investigate its effect on the development and expression of morphine analgesic tolerance and withdrawal signs in mice. Morphine tolerance and dependence were induced by twice daily morphine injection (10 mg/kg, s.c.) for 5 consecutive days. Tolerance was assessed by the hot-plate test and dependence by naloxone challenge, on the sixth day. To determine if the NO is involved in the effects of simvastatin, mice were pre-treated with l-arginine (200 mg/kg) or the NO synthesis inhibitors (L-NAME; 30 mg/kg) along with simvastatin (300 mg/kg). The results showed that acute and chronic administration of simvastatin reversed the antinociceptive tolerance of morphine and attenuated withdrawal signs in morphine-dependent mice, and this effect is reversed by l-arginine and augmented by l-NAME. Also, the concentration of NO and oxidative stress factors such as malondialdehyde content, total thiol, and glutathione peroxidase (GPx) activity in brain tissues was evaluated. Chronic administration of simvastatin reduced NO and malondialdehyde, and increased total thiol and GPx levels in the cerebral cortex and hippocampus of morphine-dependent mice which were antagonized by l-arginine, and augmented by l-NAME. In summary, simvastatin attenuates morphine-induced antinociceptive tolerance and withdrawal symptoms, at least partly, through antioxidative properties and nitric oxide pathway.

Effect of pretreatment with simvastatin on spinal cord ischemia-reperfusion injury in rats

OBJECTIVE

The aim of this study was to evaluate the pretreatment effect of simvastatin on spinal cord ischemia-reperfusion injury.

DESIGN

Prospective, interventional study.

SETTING

University research laboratory.

PARTICIPANTS

Forty-five male Sprague-Dawley rats.

INTERVENTIONS

Rats were treated with oral simvastatin, 10 mg/kg (simvastatin group; n = 15) or saline (control group; n = 15) for 5 days before ischemia. Spinal cord ischemia was induced using a balloon-tipped catheter placed in the proximal descending aorta in the control and simvastatin groups, but not in the sham group (n = 15).

MEASUREMENTS AND MAIN RESULTS

Neurologic function was assessed daily using the motor deficit index until 7 days after reperfusion. After the last neurologic evaluation, a histologic examination of the spinal cord was performed. At day 1 after reperfusion, the simvastatin group showed a significantly lower motor deficit index compared with the control group (2.0, 2.0-2.0, v 4.0, 3.5-5.0; p < 0.001). This trend was sustained at day 7 (2.0, 1.5-2.0, v 4.0, 3.0-4.0; p < 0.001). The simvastatin group displayed a significantly larger number of normal motor neurons compared with the control group (mean ± SD, 31.7 ± 6.1 v 20.4 ± 4.4; p < 0.001). However, compared with the sham group, the simvastatin group displayed fewer intact motor neurons (sham group, 38.5 ± 5.1; p = 0.005).

CONCLUSIONS

Pretreatment with simvastatin, 10 mg/kg, given orally for 5 days before the ischemia-reperfusion insult, improved the neurologic outcome and preserved more normal motor neurons compared with the control group in a rat model of spinal cord ischemia-reperfusion.