Antinociceptive effect of thymoquinone in diabetic rats and the role of serum lipid peroxidation

Authors

Abstract

 Background and Objective: Hyperalgesia is one of the signs
of diabetes mellitus that affects the life quality of patients. Nigella
sativa-derived thymoquinone exhibits antidiabetic
and anti-inflammatory effects. This study was designed to investigate the
antinociceptive effect of thymoquinone (TQ) in streptozotocin-diabetic rats.   Materials and Methods: Rats were divided into control, high
dose TQ-treated control, diabetic, sodium salicylate (SS)-treated control and diabetic,
and high and low dose TQ-treated diabetic groups. TQ was administered i.p. at
doses of 2.5 and 5 mg/kg one week after diabetes induction by streptozotocin
for 5 weeks.    Results: TQ treatment of diabetic rats reduced pain score
in acute and chronic phases of the formalin test (p < 0.05). Meanwhile, SS
administration significantly reduced pain score only at chronic phase of the
test (p < 0.01). Regarding hot tail immersion test, diabetic rats showed a
significant reduction in tail flick latency as compared to control ones
(p < 0.05) and TQ treatment of diabetic rats slightly increased this latency
relative to untreated diabetics but the existing difference was not
statistically significant. In addition, high-dose TQ significantly reduced serum
level of MDA in diabetic group (p < 0.05).   Conclusion: Taken together, administration of TQ could
attenuate nociceptive score in both phases of formalin test in experimental
model of diabetes mellitus and has no obvious effect on thermal pain threshold
and part of this effect is exerted through attenuation of lipid peroxidation in
peripoheral tissues of the body. 

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