Indeed, in lactotroph cells, a correct function of the dopamine signalling pathway is needful to limit PRL synthesis and secretion, and cell growth and proliferation, to minimize the development of lactotroph hyperplasia, or lactotroph differentiation and expansion, with a consequent formation of PRL-secreting tumors leading to a state of pathological hyperprolactinemia (32–37). This evidence concerns the gene PRL and hyperprolactinemia.