Hypercholesterolemia induces the release of endogenous opioids from the hypothalamus, which along with corticosteroids, suppresses hypothalamic gonadotrophin-releasing hormone (GnRH) and leads to reduced secretion of LH and FSH, and a decrease in testosterone (Ramaswamy and Weinbauer, 2015 ▶). This evidence concerns the gene PLOD1 and familial hypercholesterolemia.