Diallyl disulfide protects against rectal cancer in vivo model of male rabbits: II-Analysis of histological and cytogenetic variations

The present work was conducted to perform a short-term comparative analysis and evaluate the anti-neoplastic effects of diallyl disulfide on rectal carcinogenicity via histopathological changes, chromosomal aberrations, and mitotic index induced by 1,2-dimethylhydrazine on male rabbits (Orectolagus cuniculus). The histological changes that can be seen microscopically showed that 1,2-dimethylhydrazine at the suggested dose (20 mg/kg) produced significant alterations in rectal mucosa of 1,2-dimethylhydrazine group. The presence of dysplasia was regarded as an early histopathological changes in the precursor lesions of rectal cancer. Three varieties of intrachromosomal instability were detected, deletions (1p12, 15q23, 21q14), duplications (5q14; 13q23, 14q21) and ring (X) chromosome with a highly significant increase (P<0.05) in comparison with control. Such aberrations were markedly inclined in 1,2- dimethylhydrazine group after treatment by diallyl disulfide and the pretreated group  that received diallyl disulfide prior to 1,2-dimethylhydrazine injection with a significant decrease (P<0.01). Mitotic index ranged from 46, 22, 17, and 18% to 20% in 1,2-dimethylhydrazine, 1,2-dimethylhydrazine +diallyl disulfide, diallyl disulfide, control, and pretreated diallyl disulfide +1,2-dimethylhydrazine groups, respectively. Examination of 1,2-dimethylhydrazine group showed that it caused neoplastic changes with cytogenetic abnormality identified by hematoxylin and eosin staining and G-banding analysis, respectively. Such changes were similar to those seen in human sporadic colorectal carcinogenesis. Key words: Rectal cancer, diallyl disulfide, dimethyl hydrazine, chromosomal aberrations, intrachromosomal instability, mitotic index.