Melatonin and Vitamin C Attenuate Cassava Diet-Induced Alteration in Thyroid Function

Abstract Background Cyanide is present in cassava and is well known to cause adverse effects on the male reproductive functions. This study evaluated the effect of melatonin and/or vitamin C on body weight, thyroid function and reproductive parameters in male Wistar rats treated with cyanide-enriched cassava-diet (CD), and their possible mechanisms of actions. Methods Forty-five (45) animals were divided into 9 groups (n = 5 each) that received the following treatments for 28 days. Groups I-III received normal saline (control), melatonin (15 mg/kg), and vitamin C (100 mg/kg) only. Groups IV-VI received 40% CD, while groups V and VI were additionally treated with melatonin only and melatonin and vitamin C respectively. Groups VII-IX received 80% CD, but groups VIII and IX were additionally treated with melatonin only and melatonin and vitamin C respectively. Results Melatonin and/or vitamin C supplement increased body weight in CD-treated rats. The sperm count (but not other semen parameters) was increased by CD and melatonin, while combination of melatonin and vitamin C in CD-treated rats increased all semen parameters. Neither CD alone nor its co-administration with melatonin and /or vitamin C affected plasma luteinising hormone (LH) and testosterone. The 40% CD and 80% CD increased triiodothyronine (T3), but the increase by the former was abolished by melatonin alone while the increase by the latter was neither affected by melatonin alone nor its combination with vitamin C. Moreover, the 40% CD and 80% CD increased thyroxine (T4), but was neither affected by melatonin alone or its combination with vitamin C. The levels of thyroid stimulating hormone (TSH) were not different across all treatment groups. Both 40% CD and 80% CD increased the thiocyanate level, which was ameliorated by melatonin but abolished by combination of melatonin and vitamin C. Both 40% CD and 80% CD decreased the total antioxidant capacity (TAC) level, which was abolished by melatonin. Conclusion In conclusion, this study suggests that CD increases weight gain, thyroid hormone and oxidative stress, which were attenuated by anti-oxidants melatonin and vitamin C.