Analgesic Effects of Thiamine in Male Long Evans Rats

Abstract

Background: The concept of analgesic effects of thiamine along with other B vitamins has been supported since long by various clinical and experimental evidences, though effects of individual thiamine on pain are yet to be clearly demonstrated. Objective: To assess the effects of increasing doses of thiamine supplementation on pain. Methods: Forty-eight (48) male Long Evans rats (200±20 gm) were given thiamine (100, 200, 250, mg/kg/day; experimental) or normal saline (5 ml/kg/day; control) intraperitonealy (i.p) for 7 consecutive days. The analgesic activity was evaluated by three experimental pain models, hot (52±0.5 0 C) water tail immersion test, the interphase (6 th -15 th minutes) of formalin (50 µl, 2.5%, subcutaneous) test and acetic acid (2%, i.p) induced writhing test. Statistical analysis was done by ANOVA followed by Bonferroni post hoc test and p≤0.05 was considered as significant. Results: In tail immersion test, %MPE significantly increased after 200 (p≤0.05) and 250 (p≤0.001) mg/kg of thiamine. In the formalin test, thiamine significantly lowered the jerking frequency (p≤0.05, p≤0.001, p≤0.001, respectively) and duration of flexing and licking (p≤0.001, in all doses), compared to control. In addition, in writhing test, significant increment in latency of appearance of 1 st writhe (p≤0.001, in higher 2 doses) and significant decrement in frequency of writhes (p≤0.01, p≥0.001, p≤0.001, respectively, in all doses) were observed. Conclusion: The results of this study conclude that, repetitive administration of thiamine may cause alleviation of pain through central as well as peripheral inhibitory mechanisms, which is dose dependent as well.

Delayed Influence of Spinal Cord Injury on the Amino Acids of NO• Metabolism in Rat Cerebral Cortex Is Attenuated by Thiamine

“…After surgery, the rats were placed into the individual cages with heating pad. Previous protocols ( 35 – 37 ) were adapted to this study involving postoperative administration of thiamine, which is known for analgesic and anti-inflammatory effects ( 30 – 33 ). Within the first 3 days after the operation, antibiotic (gentamicin, 40 mg/kg) was injected subcutaneously (s.q.)…”

“…On the other hand, inflammation, oxidative stress, autophagy, and endoplasmic reticulum stress leading to neurodegeneration, are known to be induced by thiamine deficiency ( 24 – 27 ), and we have recently reported that a high dose of thiamine results in a long-term optimization of the amino acid metabolism ( 28 ), potentially contributing to beneficial influence of thiamine on brain pathologies ( 29 ). It is also known that thiamine exerts analgesic and anti-inflammatory effects in different rat models including nerve injuries ( 30 – 33 ). The aim of this work is to estimate long-term changes in the NO • -related compounds in the cerebral cortex after SCI, and their potential normalization by thiamine treatment.…”