PRL and obesity due to melanocortin 4 receptor deficiency: Some frequently used dopamine receptor antagonists, such as metoclopramide, domperidone and risperidone, elevates both serum and central (cerebrospinal fluid) PRL levels and by doing so do not disturb energy and glucose metabolism, while other dopamine antagonists, such as olanzapine, induce impaired glucose tolerance and obesity since they do not increase central prolactin levels (78).