Experimentally induced hyperprolactinemia led to a significant reduction in the proportion of LH-secreting cells [60] and impaired the postcastration increase in pituitary GnRH receptors [61], whereas in vitro treatments with prolactin suppressed both basal and GnRH-stimulated LH secretion from pituitary fragments [43]. The gene discussed is PLOD1; the disease is hyperprolactinemia.