The effect of experimental low zearalenone intoxication on ovarian follicles in pre-pubertal bitches

Abstract

Companion animals, including bitches, may be exposed to zearalenone (ZEN) toxins that are often present in feed, and ZEN intoxication may lead to ovarian dysfunction. This study involved evaluation of the degree of ZEN-induced hypo stimulation of ovary by determination of proliferative and apoptotic indices and description of the ultra-structural organization of ovarian follicles in pre-pubertal bitches subjected to experimental, long-term exposure to low-dose ZEN mycotoxicosis. The experiment involved 30 clinically healthy, immature Beagle bitches aged approximately 70 days with initial average body weight of 8 kg, randomly divided into three groups of 10 animals each: two experimental groups (EI and EII) and a control group (C). Over a period of 42 days, ZEN was administered per os to EI animals at a dose of 50 μg/kg BW, and to EII bitches at a dose of 75 μg/kg BW. Control group animals were fed placebo containing no ZEN for 42 days. Analytical samples of the mycotoxin were administered daily in gelatin capsules before morning feeding. All the bitches were subjected to ovario-hysterectomy at the end of the experiment. Proliferation index (PCNA method) and apoptotic index (TUNEL test) values were determined by immune-histological analyses. The median for apoptotic index was determined at 13.45 for group EI, 17.84 for group EII, and 8.59 for group C. The median for proliferation index was determined at 35.25 for group EII, 42.44 for group EI, and 70.60 for group C. The results of ultra-structural examinations of the ovaries revealed that experimental, ZEN-induced hyperestrogenism enhanced apoptosis and lowered the proliferative ability of follicular cells what contributed to organelle destruction in pre-pubertal bitches. The changes observed were particularly advanced in EII animals, which were administered a higher dose of ZEN.

The effects of experimental administration of low doses of zearalenone on the histology of ovaries in pre-pubertal bitches

“…The above has been confirmed by the results of our unpublished study (Gajęcka 2013) which determined apoptotic and proliferative indices of ovarian follicles in the same bitches. Intensified apoptosis and slower proliferation were observed in primordial and primary follicles in both oocytes and in follicular cells.…”

The effect of selected environmental Fusarium mycotoxins on the ovaries in the female wild boar (Sus scrofa)

“…ZEN blocks ERs or mimics steroid hormones, in particular estradiol (Brevini et al 2005). Even at very low concentrations, ZEN and its metabolites stimulate cell proliferation sensitive tissues in various animal species, which is consistent with principles of hormesis (Frizell et al 2011, Gajęcka et al 2011, Gajęcka 2013. At concentrations below NOAEL (threshold values), many toxic compounds, including undesirable substances such as ZEN, exert stimulating/adaptive effects (Heberer et al 2007, Dobrzański andFornalski 2011), but these effects are weaker than those in organisms not exposed to a given toxic substance.…”

Mycotoxin binders potential on histological of ovary mice exposed by zearalenone

“…The study of ZEN by Gajecka [8] found that, ZEN can suppress the proliferative activity of follicle cells contained in the ovarian cortex. The decline in follicular cells count was not followed with oocyte maturation process and follicular liquor influx that physiologically fills the antral space in the de Graaf’s follicle before ovulation process.…”