Reproduction Abstracts

Introduction: Deoxynivalenol (DON) is a major mycotoxin found in animal feed, one of its major actions is to activate the ribotoxic stress response (RSR) in different cells types. DON has been shown to inhibit progesterone secretion from porcine granulosa cells, but its effect in the cow is unknown. The objective of this study was to determine the effects of DON on bovine granulosa cells in vitro.

Materials and methods: Bovine granulosa cells from follicles 3–5 mm diameter were placed in serum-free culture. Dose- and time-course studies with DON were performed with a maximum dose of 100 ng/ml. Oestradiol and progesterone secretion was measured by RIA, apoptosis was measured by Annexin Flow Cytometry, activation of two major RSR pathways (ERK1/2 and p38) was assessed by western blot, and target gene mRNA levels were measured by real-time PCR.

Results: Treatment with DON resulted in a significant inhibition of oestradiol (P<0.05) and progesterone (P<0.05) secretion, and an increase in the proportion of apoptotic cells (P<0.05) after 4 days of treatment. Western blot demonstrated significant up-regulation of ERK1/2 (P<0.05) and p38 (P<0.005) phosphorylation within 15–30 min of adding DON. We then determined the effect of DON on ERK1/2 target genes; EGR1 and FOS mRNA levels were transiently stimulated with maximum levels at 1 h of adding DON, whereas COX2 and GADD45B mRNA levels were upregulated but not until 24 h after DON treatment (P<0.05). Taken together these results suggest that DON activates the RSR in bovine granulosa cells and negatively impacts cell health.