EC Clinical and Medical Case Reports

Male and female parent rats were treated with carbendazim at 6.25, 12.5, 25, and 50 mg/kg bw/day, flutamide at 2.5 mg/kg bw/day, or in combination at the same doses. The mated female rats with a vaginal plug continued drug treatments according to their assigned group for a further 21 days. For F1 adult rats, due to embryo lethality carbendazim doses were adjusted to 1.56, 3.13, 6.25, and 12.5 mg/kg bw/day; and in combination to 6.25 and 12.5 mg/kg bw/day. For F2 adult rats, carbendazim doses were further adjusted to 0.39, 0.78, 1.56, 3.13, and 6.25 mg/kg bw/day; and in combination to 0.78, 1.56, and 3.13 mg/kg bw/day. This study showed that carbendazim induced endocrine-disrupting activity including changes in anogenital distance, offspring weight, vaginal opening, preputial separation, epilepsy, and reproductive organs. For F2 offspring, carbendazim at 1.56 mg/kg bw/day induced epilepsy in 5% of males, and carbendazim at 6.25 mg/kg bw/day induced epilepsy in 3% of male and 10% of female offspring. For F3 offspring, carbendazim at 0.78 and 6.25 mg/kg bw/day respectively induced epilepsy in 13% and 20% of males and in 15% and 6% of females. Furthermore, flutamide induced epilepsy in 10% of female offspring. Our data indicate that carbendazim reduced the weights of the brain, pituitary gland, testis, and penis as well as penis width and length in male offspring while epididymis weight of male rats increased in F2 offspring but decreased in F3 offspring. Based on the above findings, we infer that androgen receptors play a vital role in epilepsy in rats.

Keywords: Carbendazim; Flutamide; Reproductive and Developmental Neurotoxicity; Epilepsy; Rat

1. Rehnberg GL., et al. “Serum and testicular testosterone and androgen binding protein profiles following subchronic treatment with carbendazim”. Toxicology and Applied Pharmacology 101 (1989): 55-61.
2. Nakai M., et al. “Acute and long term effects of a single dose of the fungicide carbendazim (methyl 2-benzimidazole carbamate) on the male reproductive system in the rat”. Journal of Andrology 13 (1992): 507-518.
3. Lim J and Miller MG. “Role of testis exposure levels in the insensitivity of prepubertal rats to carbendazim-induced testicular toxicity”. Fundamental and Applied Toxicology 37 (1997a): 158-167.
4. Carter SD., et al. “The fungicide methyl 2-benzimidazole carbamate causes infertility in male Sprague-Dawley rats”. Biology of Reproduction 37 (1987): 709-717.
5. Cummings AM., et al. “Developmental effects of methyl benzimidazole carbamate following exposure during early pregnancy”. Fundamental and Applied Toxicology 18 (1992): 288-293.
6. Perreault SD., et al. “Use of the fungicide carbendazim as a model compound to determine the impact of acute chemical exposure during oocyte maturation and fertilization on pregnancy outcome in the hamster”. Toxicology and Applied Pharmacology 114 (1992): 225-231.
7. Carter SD., et al. “Effect of benomyl on the reproductive development of male rats”. Journal of Toxicology and Environmental Health 13 (1984): 53-68.
8. Hess RA., et al. “The fungicide benomyl(methyl1-(butylcarbamoyl)-2-benzimidazolecarbamate) causes testicular dysfunction by inducing the sloughing of germ cells and occlusion of efferent ductules”. Fundamental and Applied Toxicology 17 (1991): 733-745.
9. Lim J and Miller MG. “The role of the benomyl metabolite carbendazim I benomyl-induced testicular toxicity”. Toxicology and Applied Pharmacology 142 (1997b): 401-410.
10. Foster PMD and McIntyre BS. “Endocrine active agents: implications of adverse and non-adverse changes”. Toxicologic Pathology 30 (2002): 59-65.
11. Cummings AM and Kavlock RJ. “Gene-environment interactions: a review of effects on reproduction and development”. Critical Reviews in Toxicology 34 (2004): 461-485.
12. You L., et al. “Impaired male sexual development in perinatal Sprague-Dawley and Long Evans Hooded rats exposed in utero and lactationally to p,p’-DDE”. Toxicological Sciences 45 (1998): 162-173.
13. McIntyre BS., et al. “Effects of in utero exposure to linuron on androgen-dependent reproductive development in the male Crl:CD(SD)BR rat”. Toxicology and Applied Pharmacology 167 (2000): 87-99.
14. McIntyre BS., et al. “Androgen-mediated development in male rat offspring exposed to flutamide in utero: Permanence and correlation of early postnatal changes in anogenital distance and nipple retention with malformations in androgen-dependent tissues”. Toxicological Sciences 62 (2001): 236-249.
15. Lambright C., et al. “Cellular and molecular mechanisms of action of linuron: An antiandrogenic herbicide that produces reproductive malformations in male rats”. Toxicological Sciences 56 (2000): 389-399.
16. Wolf CJ., et al. “Effects of prenatal testosterone propionate on the sexual development of male and female rats: A dose-response study”. Toxicological Sciences 65 (2002): 71-86.
17. Anway MD., et al. “Epigenetic transgenerational actions of endocrine disruptors and male fertility”. Science 308 (2005): 1466-1469.
18. Lu SY., et al. “Endocrine-disrupting activity in carbendazim-induced reproductive and developmental toxicity in rats”. Journal of Toxicology and Environmental Health, Part A 67 (2004): 1501-1515.
19. Morinaga H., et al. “A benzimidazole fungicide, benomyl, and its metabolite, carbendazim, induce aromatase activity in a human ovarian granulose like tumor cell line (KGN)”. Endocrinology 145 (2004): 1860-1869.
20. Yamada T., et al. “Functional genomics may allow accurate categorization of the benzimidazole fungicide benomyl: lack of ability to act via steroid-receptor-mediated mechanisms”. Toxicology and Applied Pharmacology 205 (2005): 11-30.
21. Lu SY., et al. “Antagonistic and synergistic effects of carbendazim and flutamide exposures in utero on reproductive and developmental toxicity in rats”. Journal of Food and Drug Analysis 14 (2006): 120-132.
22. Hsu YH., et al. “Carbendazim-induced androgen receptor expression antagonized by flutamide in male rats”. Journal of Food and Drug Analysis 19 (2011): 418-428.
23. Lu SY., et al. “Detecting benomyl and its metabolite carbendazim inducing androgenic activity in rats by using uterotrophic and Hershberger assays”. Taiwanese Journal Agricultural Chemistry and Food Science 53 (2015): 235-250.
24. Lu SY and Tsai WR. “Benomyl- or carbendazim-induced androgen receptor disrupting might lead to spinal and bulbar muscular atrophy in multi-generations of rats”. Pharmaceutical Research 4 (2020a): 000198.
25. Lu SY and Tsai WR. “Antiandrogen flutamide might protect multi-generations of rats from androgen-dependent toxicity in spinal and bulbar muscular atrophy induced by benomyl or carbendazim”. EC Pharmacology and Toxicology 8 (2020b): 6.
26. McIntyre BS., et al. “Male rats exposed to linuron in utero exhibit permanent changes in anogenital distance, nipple retention, and epididymal malformations that result in subsequent testicular atrophy”. Toxicological Sciences 65 (2002): 62-70.
27. Ostby J., et al. “The fungicide procymidone alters sexual differentiation in the male rat by acting as an androgen-receptor antagonist in vivo and in vitro”. Toxicology and Industrial Health 15 (1999): 80-93.
28. Wolf CJ., et al. “Characterization of the period of sensitivity of fetal male sexual development to vinclozolin”. Toxicological Sciences 55 (2000): 152-161.
29. Enes AZKYUZ. “A new view of the Racine Scoring System in the pentylenetetrazol epilepsy model”. Journal of Harran University Medical Faculty 17 (2020): 306-310.
30. Heida JG., et al. “Blockade of androgen receptors is sufficient to alter the sexual differentiation of the substantia nigra pars reticulate seizure-controlling network”. Epileptic Disorders 10 (2008): 8-12.
31. Killer N., et al. “Modulation of androgen and estrogen receptor expression by antiepileptic drugs and steroids in hippocampus of patients with temporal lobe epilepsy”. Epilepsia 50 (2009): 1875-1890.
32. Nuñez JL and McCarthy MM. “Androgens predispose males to GABAA –mediated excitotoxicity in the developing hippocampus”. Experimental Neurology 210 (2008): 699-708.
33. Edwards HE., et al. “Testosterone and its metabolites affect after discharge thresholds and the development of amygdala kindled seizures”. Brain Research 838 (1999): 151-157.
34. Fanaei H., et al. “Flutamide enhances neuroprotective effects of testosterone during experimental cerebral ischemia in male rats”. Neurology (2013): 592398.
35. Ahmadiani A., et al. “Anticonvulsant effect of flutamide on seizures induced by pentylenetretrazole: Involvement of benzodiazepine receptors”. Epilepsia 44 (2003): 629-635.
36. Frye CA., et al. “Testosterone reduces pentylenetetrazole-induced ictal activity of wildtype mice but not those deficient in type I 5α-reductase”. Brain Research 918 (2001): 182-186.
37. Reddy DS and Jian K. “The testosterone-derived neurosteroid androstanediol is a positive allosteric modulator of GABAA receptors”. Journal of Pharmacology and Experimental Therapeutics 334 (2010): 1031-1041.
38. Meyer RP., et al. “Anti-epileptic drug phenytoin enhances androgen metabolism and androgen receptor expression in murine hippocampus”. Journal of Neurochemistry 96 (2006): 460-472.
39. Kaminski RM., et al. “Anticonvulsant activity of androsterone and etiocholanolone”. Epilepsia 46 (2005): 819-827.
40. Tamura H., et al. “Interaction of organophosphate pesticides and related compounds with the androgen receptor”. Environmental Health Perspectives 111 (2003): 545-552.