Prolactin (gene name PRL) is a secreted neuroendocrine pituitary hormone that acts primarily on the mammary gland to promote lactation, but has pleiotropic effects in both males and females. Prolactin is synthesized mainly by the anterior pituitary in all mammals, where secretion is under tonic inhibition by hypothalamic dopamine. Secretion can be stimulated by suckling and diurnally by estradiol in rodents during pro-estrus and mating. PRL exerts different actions through its receptors that can be found in both neurons and glial cells (astrocytes, microglia and oligodendrocytes) of the brain.It is generally believed that in vertebrates, prolactin (PRL) plays important roles in many physiological processes via activation of PRL receptor (PRLR), including water and electrolyte balance, reproduction, growth and development, metabolism, immuno-modulation, and behavior.