Abstract
The effect of prolonged aflatoxin B1 (AFB1) administration on blood serum oestradiol-17β and progesterone concentrations in goats during the luteal phase and the synchronized oestrus was investigated. Thirty-six Greek indigenous primiparous goats were used, during the oestrus period; 12 goats received, per os, 50 μg (treated group T50) and 12 goats received 100 μg (treated group T100) AFB1/day/head, respectively, for approximately 1.5 month, while 12 goats served as controls (C). On day 36 of the experiment, each goat was injected, i.m, 0.5 ml prostaglandin F2α (PGF2α). Blood samples were collected from each goat twice a week, before PGF2α injection, as well as every 4 hours from the onset to the end of the synchronized oestrus. Oestradiol-17β and progesterone concentrations in blood serum were determined using radioimmunoassay. During the whole luteal(s) phase(s), linear regression analysis revealed a significant negative dependence (P < 0.05) of oestradiol-17β and a significant positive dependence (P < 0.05) of progesterone over group (C = 0, T50 = 50, T100 = 100), in a dose dependent manner. During the synchronized oestrus, multiple linear regression analysis revealed a significant negative dependence (P < 0.05) of oestradiol-17β, as well as a significant positive dependence (P < 0.05) of progesterone over group (C = 0, T50 = 50, T100 = 100) and over time (hours, from the onset to the end of the synchronized oestrus). No significant differences were noticed among the three groups, regarding the body weight of the goats from the onset to the end of AFB1 administration, the occurrence or the duration of the synchronized oestrus presented by the goats (P > 0.05). In conclusion, prolonged AFB1 administration at doses of 100 or even of 50 μg/day/head changes the hormonal pattern in blood during the luteal phase and the synchronized oestrus of goats, being in oestrus period.
Highlights
The mechanisms, through which aflatoxin B1 (AFB1) affects the reproductive system, remain unexplained, since the effects of the toxin have not been studied extensively (Shuaib et al, 2010)
Linear regression analysis revealed a significant decrease of oestradiol-17β concentration (F = 9.98, df = 306, P = 0.002; Constant = 19.67 ± 0.81, t = 24.38, P = 6.94E-021; Group = -1.16 ± 0.37, t = -3.16, P = 0.002), as well as, a significant increase of progesterone concentration (F = 66.62, df = 306, P = 8.29E-015; Constant = 1.59 ± 0.09, t = 16.39, P = 6.94E-021; Group = 0.36 ± 0.04, t = 8.16, P = 8.29E-015) over group (C = 0, T50 = 50, T100 = 100), in a dose dependent manner
AFB1 was administered in quite lower doses, but for a longer period, and that could have influenced the ovarian activity or the above-mentioned axis
Summary
The mechanisms, through which AFB1 affects the reproductive system, remain unexplained, since the effects of the toxin have not been studied extensively (Shuaib et al, 2010). After AFB1 administration (7.5 mg/kg body weight/day for 14 days) in female rats, inhibition of oocytes growing, reduction of the ovary size and weight, reduced oestradiol-17β concentration and increased progesterone concentration in blood (Ibeh and Saxena, 1997a) were observed. The alterations in oestradiol-17β and/or progesterone concentrations during the luteal phase and/or the synchronized oestrus may have detrimental effects on subsequent reproductive life of the animals, such as shortened cycles, lower fertility, negative effects on follicle maturation, ovulation or the presence and/or the signs of the oestrus cycle
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