REPRODUCTIVE HORMONE CONCENTRATIONS AND HISTOLOGY OF THE HYPOTHALAMUS, PITUITARY, OVARY, UTERUS AND LIVER OF RABBITS FED ON AFLATOXIN LACED DIETS

Abstract

Aflatoxin effect on the liver, results in cellular hepatic damage which inhibit enzyme synthesis or lipid metabolism, causing decreased synthesis of precursor molecules for gonadal and gonadotropic hormones. The presence of aflatoxin in plasma affects animal organ functions and hormone profiles that are related to fertility. The objective of the current study were to determine plasma concentration of oestradiol, follicle stimulating hormone and luteinizing hormone. The other objectives were to determine the histology of the hypothalamus, anterior pituitary gland, ovary, uterus and liver. The association between hormone levels, aflatoxin content and histological changes of organs and quantities of aflatoxin were also determined. The study was carried out using four female New Zealand white breed of rabbits for each of treatments 1, 2, 3 and 4, which had 0, 100, 200 and 400 ppb of aflatoxin in feed dry matter respectively. Blood samples were drawn weekly from rabbits for determination of plasma oestradiol, follicle stimulating hormone and luteinizing hormone using fluorescence immunoassay technique. At the end of the study, one rabbit from each treatment group was sacrificed for the harvest of the hypothalamus, anterior pituitary gland, ovary, uterus and liver. The non-normal distributed continuous hormone level data were log transformed into normal distribution and subjected to analysis of variance and significant means separated using Tukey test. The harvested tissues of the hypothalamus, pituitary gland, ovaries, uterus and liver were processed for histological examination and the results presented in photomicrographs. Mean oestradiol levels were 18.36±7.1, 16.51±6.5, 11.35±3.4 and 7.65±2.9 pmol/ ml, follicle stimulating hormone were 0.52±0.06, 0.38±0.04, 0.32±0.07 and 0.30±0.06 mlu/ml while the mean for luteinizing hormone were 0.38±0.07, 0.26±0.08, 0.190±0.05 and 0.16±0.09 mlu/ ml for each of the treatments 1, 2, 3 and 4 respectively. Aflatoxin caused significant reduction in the plasma concentrations of oestradiol, luteinizing hormone and follicle stimulating hormone in rabbits. The hormone levels were significantly higher in controls compared to animals in treatments groups 2, 3 and 4. The hypothalamus showed degenerative changes, while the anterior pituitary gland did not show aflatoxin induced histological changes at all levels incorporated in the feed, but the ovary, uterus/fallopian tube and liver showed marked inflammatory reactions, cell infiltration and reduced number of follicles in the ovary. The ovarian was covered by dark - red blood - like fluid, an indication of the entry of leukocytes as an inflammatory reaction to the effects of aflatoxin. The liver showed inflamed hepatocyte reaction to aflatoxin. Focal inflammatory areas indicative of lesions were visible in the periportal area of the liver hepatocyte cells. The uterus showed marked defect while the fallopian tube showed vacuolization. In conclusion, aflatoxin caused reduction of oestradiol, follicle stimulating hormone and luteinizing hormone. Aflatoxin in treatment 4 affected the histology of the hypothalamus but had no effect on the pituitary gland. However, it caused inflammation and necrosis on the follicles, uterus and hepatocyte cells. The study demonstrated toxic associations between aflatoxin and hormone levels and organ changes.