ASSESSMENT OF LONG-TERM EXPOSURE TO HEAVY METALS ON THE REPRODUCTIVE SYSTEM OF LABORATORY ANIMALS; STUDY OF THE EFFECT OF LEAD NITRATE ON THE GENE EXPRESSION OF GDF9 IN THE OVARY

Objectives: This study aimed to investigate the effect of long-term lead nitrate [Pb(NO3)2] exposure on ovarian growth differentiation factor 9 (GDF9) gene expression in female BALB/c mice. Methods: Female BALB/c mice were allocated to control and Pb(NO3)2-exposed groups for 8 weeks. Ovarian GDF9 expression was assessed by one-step reverse transcription-quantitative polymerase chain reaction using GAPDH as the reference gene. Relative expression was calculated using the 2⁻ΔΔCt method, while statistical comparisons were performed on ΔCt values. Following quality-control assessment, the primary analysis included four control and seven exposed animals. Results: Mean GDF9 ΔCt was 9.49±2.46 in controls and 11.14±2.08 in the exposed group, corresponding to a numerical tendency toward lower relative GDF9 expression. The between-group difference was not statistically significant (Welch’s t-test, p=0.305; 95% CI: −2.00–5.31; Hedges’ g=0.68). Conclusion: Eight weeks of Pb(NO3)2 exposure produced a numerical tendency toward lower ovarian GDF9 messenger RNA expression; however, the between-group difference was not statistically significant. Therefore, the present findings do not establish a definitive exposure-related alteration in GDF9 expression, and further studies are needed to clarify whether prolonged lead exposure reproducibly affects ovarian GDF9 regulation.