PLOD1 and hyperprolactinemia: Although hyperprolactinemia impairs the proper function of the male gonad by either decreasing the pulse generating activity of gonadotropin-releasing hormone (GnRH) or directly inhibiting the secretion of testosterone at the Leydig cells (Horseman et al., 2006), the insignificant increase in FSH and LH of the exposed rats suggests a dysfunction in the testis of the exposed rats.