Green tea can supress rabbit ovarian functions in vitro and in vivo.

The aim of present study was to evaluate the action of green tea and its constituents on rabbit ovarian functions and some non-reproductive indexes. In in vitro experiments, rabbit ovarian fragments were cultured with green tea constituents - epigallocatechin-3-gallate (EGCG), green tea polyphenols (GTPP) and resveratrol (RSV) (at 0, 1, 10 or 100 µg/mL medium). The accumulation of an apoptosis marker - caspase 3 and the release of progesterone (P4) and testosterone (T) were measured. In in vivo experiments, does were fed a standard diet or a diet enriched with green tea powder. The weight gain, mortality, ovarian length and weight, conception and kindling rate, number of liveborn, stillborn, and weaned pups, diameter of ovarian follicles and some blood haematological and biochemical parameters were analysed. Culture of ovarian fragments with EGCG increased accumulation of caspase 3, whilst both GTTP and RSV decreased it. EGCG inhibited both P4 and T output, GTPP stimulated P4 and inhibited T, whilst RSV promoted release of both P4 and T. Feeding with green tea increased ovarian length and diameter of ovarian non-ovulated peri-ovulatory haemorrhagic but not of primary and secondary growing follicles. Furthermore, green tea reduced conception and kindling rate, the number of liveborn and weaned pups, increased female mortality but not their weight gain. It reduced platelet distribution width, but it did not affect other haematological and biochemical indexes. These observations suggest that dietary green tea can reduce rabbit doe's viability, ovarian functions and fecundity, perhaps due to changes in ovarian cell apoptosis, steroid hormones release and blockade of the ovulation of large ovarian follicles. The anti-reproductive action of green tea could be due to its constituent - EGCG with pro-apoptotic and anti-steroid hormone properties.

Histological characteristics of ovarian follicle atresia in dairy cows with different milk production.

Follicle atresia in mammals is a universal phenomenon characteristic by degenerative morphological changes in granulosa and theca cells. The unfavourable effect of milk production in relation to fertility has been studied starting from the 70s of the last century; however, there is no unambiguous and persuasive data on association of ovarian atresia with milk yield of dairy cows. The aim of this study was to define histological signs of ovarian follicle atresia in dairy cows in relation to their milk production. The ovaries were recovered from slaughtered Holstein dairy cows assigned into two groups according to average level of annual milk production: Group 1 (n = 25)-low (≤8,000 kg/year) and Group 2 (n = 23)-high (≥8,000 kg/year). Atresia of antral follicles was evaluated on the basis of histopathological image (staining with basic fuchsine and toluidine blue) of nonovulated follicles, classified into five categories: an initial atresia, cystic atresia, obliterated atresia, atresia with luteinization of the granulosa and follicle structures of the fibrous body-corpus fibrosum. We found that the histopathological image of follicle atresia in groups of low-milk- or high-milk-producing cows is essentially similar. Prevalent form of atresia in follicles of all experimental cows was the formation of fibrous bodies and obliterated atresia. The occurrence of fibrous bodies was significantly higher (55.44%) in low-milk-producing cows compared with high-milk-producing cows (34.61%). In the same way, the higher incidence of obliterated atresia was recorded in ovarian follicles from cows with the lower milk production (36.96%) compared to the cows with the higher milk production (25.48%). In contrast, ovaries from lower milk-producing cows showed lower (p < 0.05) incidence of initial (p < 0.001) and cystic (p < 0.05) follicle atresia than ovaries from the higher milk-producing cows. Our results show that cows in the higher lactation group showed more initial and cystic atresia, what may adversely affect the fertility of dairy cows.

Yucca schidigera can promote rabbit growth, fecundity, affect the release of hormones in vivo and in vitro, induce pathological changes in liver, and reduce ovarian resistance to benzene.

This study evaluated the effect of Yucca schidigera (YS) extract on the physiological, reproductive, and endocrine indexes of New Zealand White rabbit does. Six-week-old rabbit does were fed a standard diet (control group) or a diet enriched with 5 or 20g of Y powder extract per 100-kg feed mixture for 350days. The does were artificially inseminated after induction of superovulation. Weight gain; conception and kindling rate; viability of pups and mothers; histopathological state of liver and muscle; plasma levels of progesterone (P4), oxytocin (OT), and prostaglandin F (PGF); and the release of P4, insulin-like growth factor I (IGF-I), OT, and PGF by isolated ovarian fragments and their response to the addition of benzene were analyzed. YS extract supplementation promoted weight gain and induced histopathological changes in the liver (creased vacuolization and occurrence of fuchsinophile inclusions in hepatocytes, liver fibrosis, hyperemia, occurrence of Kupffer cells, signs of necrosis and inflammation). YS consumption was not associated with changes in muscle (occurrence of fuchsinophile inclusions and signs of atrophy, interstitial edema, and inflammation), although Y2 increased muscle vascularization. YS supplementation increased conception and kindling rates but did not affect viability of pups or adult animals. Moreover, it enhanced plasma OT and PGF levels; plasma P4 concentration was increased by low-dose YS, but decreased by high-dose YS. Cultured ovarian fragments isolated from YS-fed does released more P4 and PGF and less IGF-I than ovarian fragments of control animals. However, YS supplementation did not affect ovarian OT release. Benzene alone did not influence the release of hormones by ovaries of control does. YS supplementation induced the inhibitory effect of benzene on the release of PGF, but not on other ovarian hormones. Collectively, these results suggest that dietary supplementation of YS extract can stimulate rabbit performance (growth and fecundity), which may be due to the promotion of P4, OT, and PGF release. It could, however, induce some pathological changes in the liver and reduce resistance of ovaries to the environmental contaminant benzene.

Yucca schidigera extract can promote rabbit fecundity and ovarian progesterone release.

The aim of the present in vivo study was to determine the effects of yucca powder extract added to the rabbit females feed mixtures on kindling and conception rate. Rabbit does of the experimental groups were fed with the standard diet enriched with supplement of yucca dry extract at doses of 5 g/100 kg feed (E1 group) or 20 g/100 kg feed (E2 group) for 50 days. In our preliminary in vivo results, we shown that conception rate was significantly higher in both experimental E1 and E2 groups (82.4% and 100.0%, respectively) than in the control group (47.1%). The kindling rate was also significantly higher in the experimental groups (70.6% and 100.0%, respectively) than in the control group (41.2%). The differences between control and yucca-treated groups in the number of liveborn, stillborn, and weaned pups per doe were not statistically significant. To understand possible endocrine mechanisms of yucca action on fertility rate, we have examined the influence of yucca extract additions on the release of steroid hormones by isolated and cultured rabbit ovarian fragments. Yucca additions promoted release of progesterone (at dose of 1 µg/mL, but not at doses of 10 and 100 µg/mL). Yucca addition at these doses did not affect testosterone or estradiol release. Our observations show the stimulatory effect of yucca consumption on rabbit fecundity, which can be due to its direct stimulatory influence on ovarian progesterone but not on testosterone or estradiol output.