Effect of ambient lead on progesterone and pregnancy-associated glycoprotein 1 and their relationship with abortion in Zaraibi goats: a field study

Abstract

This study aimed to investigate the impact of ambient lead (Pb) exposure on progesterone (P₄) and pregnancy-associated glycoprotein 1 (PAG1) and their relationship with abortion in Egyptian Zaraibi goats (C. hircus). To achieve this, 40 female goats (does) were mated with highly fertile male goats, resulting in a total of 28 pregnant goats. Eight of them aborted, and each of the 12 pregnant goats gave birth to one kid, whereas the remaining eight gave birth to twins. The levels of PAG1, P4, and Pb in serum were estimated by enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA), and inductively coupled plasma mass spectrometry (ICP-MS) respectively. Statistically, the repeated measure two-way ANOVA, regression analysis, correlation coefficient, and receiver operating characteristic (ROC) curves were applied. The current data demonstrated that the levels of blood Pb in aborted goats were significantly higher than those in non-aborted goats at the early, mid, and late gestations, and this was followed by significant decreases in serum PAG1 and P₄. Furthermore, there were substantial inverse associations between blood Pb concentration and levels of PAG1 and P₄, with markedly negative correlation coefficients of - 0.88 and - 0.77, respectively, in aborted goats. The threshold level of Pb required to cause abortion was ≥ 32.08 μg/dl, but for PAG1 and P₄ were respectively ≤ 0.95 ng/ml and ≤ 0.48 ng/ml. Additionally, threshold levels of ≥ 12.34 ng/ml and ≥ 31.52 ng/ml for P₄ and PAG1, respectively, were needed to deliver twins. In conclusion, pollution-induced increases in Pb bioavailability resulted in dramatic decreases in P₄ and PAG1 levels, leading to abortions. PAG1 and P₄ levels are also key factors in determining whether Zaraibi goats will give birth to twins.

Keywords: Abortion; Bioavailability; Lead; Pregnancy-associated glycoproteins; Progesterone; Zaraibi goats.

Photo 1

Transrectal ultrasonographic photos of two pregnant does. One had a single embryo at day 32 while the other had twins embryos at day 26

Fig. 1

The relationship between levels of lead (Pb, μg/dl) with each of the progesterone (P₄, ng/ml) and pregnancy-associated glycoprotein (PAG1, ng/ml) content in the sera of aborted Zaraibi goats. The symbol * indicates a significant correlation coefficient between the studied parameters. The letter x indicated the levels of Pb ions in sera, whereas the letter y is the levels of PAG1 and P₄ throughout the gestation stages

Fig. 2

The receiver operating characteristic (ROC) curve determines the threshold level of serum P₄ (ng/ml) and PAG1 (ng/ml) required for twin pregnancy. The area under the curve (AUC) and its statistics are represented