Effect of avitaminosis A and hypervitaminosis A on urinary bladder carcinogenicity of N-(4-(5-Nitro-2-furyl)-2-thiazolyl)formamide.

The effect of vitamin A deficiency and hypervitaminosis A on the urothelial carcinogenicity of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formanmide (FANFT) was determined in female weanling Sprague-Dawley rats. Vitamin A deficiency resulted in squamous metaplasia of the urinary bladder and high incidences of cystitis, ureteritis, and pyelonephritis. Administration of FANFT to vitamin A-deficient rats appeared to accelerate the carcinogenic process, with earlier appearance of urinary bladder tumors and the development of ureteral and renal pelvic carcinomas. Most of these tumors were squamous cell, occasionally with transitional cell foci. Hypervitaminosis A prevented the appearance of squamous metaplasia and squamous cell neoplasia in rats fed FANFT, but it did not inhibit the formation of transitional cell hyperplasia or neoplasia in comparison to rats receiving normal levels of vitamin A and FANFT.