Impairment of caprine oocyte maturation in vitro and alteration of granulosa cells functions by widely used fungicide mancozeb.

Mancozeb is classified as an endocrine disruptor; thus the present study was carried out to investigate the impact of mancozeb on mammalian ovarian functions using in vitro caprine oocyte maturation and granulosa cell culture models. Caprine cumulus oocyte complexes (COCs) and granulosa cells were cultured under standard culture conditions and treated with mancozeb concentrations of 0.3, 3, and 30 µg/ml along with a control for 24 h and assessed. Granulosa cell viability and progesterone concentration in spent culture media after treatments were also assessed. Mancozeb significantly decreased (P < 0.05) the oocytes cumulus expansion and the maturation of caprine oocytes. Marked changes in granulose cell morphology were observed with 30 µg/ml mancozeb and significantly reduced (P < 0.05) cell viability. Interestingly, the same concentrations significantly increased (P < 0.05) the progesterone secretion by the cells. Significant reduction of granulosa cells viability and reduction of cumulus expansion and suppression of metaphase plate formation in oocyte can impair the fertilization ability and developmental potential of the oocytes. High progesterone concentration due to mancozeb treatment may suppress LH surge and suppress ovulation. In conclusion, mancozeb suppresses granulosa cells viability, reduces cumulus expansion, and suppresses metaphase plate formation but induces progesterone secretion from granulosa cells that may inhibit LH surge for ovulation process.

Angiotensin II secretion by the bovine oviduct is stimulated by luteinizing hormone and ovarian steroids.

Angiotensin II (Ang II), a vasoactive peptide, is secreted by the bovine oviduct and is involved in modulation of local oviductal contraction. Ang II biosynthesis and release during the normal estrous cycle and the effects of luteinizing hormone (LH) and ovarian steroids on biosynthesis and secretion of Ang II were investigated. During the preovulatory period, increases in mRNA expression for Angiotensin converting enzyme 1 (ACE-1) and release of Ang II peptide were detected. Microdialysis of oviductal segments in vitro showed that LH alone significantly increased Ang II release, and combined infusion of LH+E(2)+P(4) caused an increase in Ang II release. In cultured oviductal epithelial cells, LH increased Ang II release and ACE-1 mRNA expression, and E(2)+P(4) enhanced stimulatory effect of LH on Ang II release and ACE-1 mRNA expression. Thus, it can be concluded that the oviductal Ang II system is upregulated by LH and ovarian steroids during the periovulatory period and may enhance local oviductal contraction. These events could stimulate transport of gametes to the fertilization site.