RESUMEN
BACKGROUND: Soya supplements are used in the treatment of neuropathic pain. Previous reports reveal that consumption of soy diet before nerve injury prevents the development of neuropathic pain in rats. Biochanin-A, a soy isoflavone, has a naturally occurring inhibitor of fatty acid amide hydrolase (FAAH) that metabolized endocannabinoids. OBJECTIVE: The objective was to evaluate efficacy of biochanin-A in streptozotocin (STZ) induced neuropathic pain in rat model. MATERIALS AND METHODS: Diabetes mellitus was induced by an injection of STZ at a dose of 45 mg/kg, i.v. into tail vein of male albino Wistar rats. Biochanin-A was dosed at 0.1, 1 and 5 mg/kg by intraperitoneal (i.p.) administration in diabetic neuropathic rats. Mechanical hyperalgesia and allodynia was measured using Randall-Selitto analgesymeter and manual von Frey filaments of increasing weights respectively. Paw withdrawal threshold (PWT) and percent PWT was determined with respect to both hyperalgesia and allodynia. RESULTS: Treatment of biochanin-A at three different levels of 0.1, 1 and 5 mg/kg had not significantly altered serum glucose levels throughout the treatment period. In hyperalgesia study, acute treatment with higher dose exhibited 51.1% reversal of paw withdrawal threshold (PWT) while with chronic treatment, efficacy declined to 22.5% reversal of PWT. In allodynia study, acute treatment reversed PWT by 79.4% while with chronic treatment, efficacy was raised to 88.2% reversal of PWT. CONCLUSION: Biochanin-A demonstrated better efficacy in reversing mechanical allodynia than mechanical hyperalgesia. Biochanin-A could be a good drug candidate for further studies to establish the mechanism of attenuation of neuropathic pain.
