Open Access Medical Books



Edited by György M. Nagy and Bela E. Toth .

244 pages . 
Open Access .

Prolactin is a polypeptide hormone that is synthesized in and secreted from the lactotrophs of the anterior pituitary gland. The name of the hormone was originally given 80 years ago based on the fact that bovine pituitary extract causes growth of the crop sac and stimulate the elaboration of crop milk in pigeons[1]. Nowadays, we already know that prolactin plays multiple pivotal roles in control of general homeostasis[2-5]. Without giving a detailed list, rather some of them will be highlighted here. The classical role can be seen in mammals where prolactin stimulates the mammary glands to produce milk during lactation and the development of corpus luteum of the ovary to secrete its hormone i.e. progesterone.
Its osmoregulatory role is also well defined. It has a critical role in fish, so it is also called a “freshwater-adapting” hormone[6]. Plasma prolactin levels may follow the changes of environmental milieu, i.e. be lower in seawater fish, but increased in freshwater.
During the last two decades we have learned that prolactin has a prominent and well defined role in the regulation of immune function[7,8]: as an immune modulator it enhances the proliferative response, but also has a role in certain autoimmune diseases as a pathoclinical indicator in multi-organ and organ specific autoimmune diseases (e.g. in lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjogren's syndrome,  Hashimoto's thyroiditis, multiple sclerosis (MS), psoriasis, etc)[9, 10, 11]. Prolactin may also participate in the development of immune tolerance between the fetus and the maternal organism during pregnancy[12]. Several experimental and also clinical evidences confirming the relationship between prolactin and the immune system have required toopen new “sub-folder” for the role of prolactin in “immune-biology”, “immuneendocrinology” and “neuroimmune-modulation”, as well as for non-clinical and clinical contributions to the search for potential new drugs in the development process.
The physiological role of prolactin is still important in the classical fields of reproduction. Prolactin seems to be involved in the central control of sexual behavior  and activity. There is a brief and sudden elevation of prolactin during orgasm indicating that it may have a role in the “gratification” during sexual acts as well[13].
On the other hand, a nondrug related female sexual dysfunction (FSD), affecting up to 1 in 10 US women, manifested with a decreased sexual desire could also be associated with increased prolactin levels [14]. A chronic hyperprolactinemia is clinically associated with hypogonadotropic hypogonadism and sexual dysfunction as well, while treatment of hyperprolactinemia restores normal sexual function both in men  and women[15].
Moreover, prolactin levels and our behavior are potentially also connected. Prolactin is higher during periods of nursing in some species, but also in human during “maternal” as well as “paternal” behavior: fathers of infants have elevated prolactin levels [16].
Prolactin stimulates proliferation of oligodendrocyte precursor cells (they are cells that differentiate into oligodendrocytes, and they are responsible for the formation of myelin sheet of axons in the central nervous system (CNS)[17,18]. Interestingly, high prolactin levels stimulate the proliferation of olfactory epithelium[19].Prolactin can also be found in amniotic fluid and contributes to surfactant synthesis of fetal lungs at the end of pregnancy[20].Since pituitary prolactin is under a close and mainly inhibitory control of hypothalamic dopaminergic system, it is predictable that drugs attenuating pathological neurotransmitter levels (like in schizophrenia, mood disturbances, etc) may have potential side effect resulting in clinical signs associated with or caused by hyperprolactinemia. Some of the effective antipsychotic treatments may have medication related adverse drug reactions appear in more than two-thirds of the patients [21, 22, 23],  indicating the continuous need to search for prolactin-sparing solutions. 
Furthermore, we are now aware that synthesis and secretion of prolactin is not restricted to the anterior lobe of the pituitary gland, but other organs and individual cells can also produce it. Indeed, the multiple roles and sources of prolactin had led Bern and Nicoll (1968), to suggest renaming it to “omnipotin” or “versatilin” [24]. This book provides the headlines to follow a course of cumulated knowledge on prolactin research during the last two-three decades and it may also help us understand some of the concerns that we face today.

György M. Nagy and Dr Bela Ernest Toth


 1 Prolactin and Angiogenesis: Biological Implications of Microheterogeneity 1 Kambadur Muralidhar and Jaeok Lee

 2 In vitro Effects of the Prolactin, Growth Hormone and Somatolactin on Cell Turnover in Fish Esophagus: Possible Mode of Opposite Osmoregulatory Actions of Prolactin and Growth Hormone 21 Hideya Takahashi, Hiroki Kudose, Chiyo Takagi, Shunsuke Moriyama and Tatsuya Sakamoto

 3 Use of the Bovine Prolactin Gene (bPRL) for Estimating Genetic Variation and Milk Production in Aboriginal Russian Breeds of Bos taurus L. 35  I.V. Lazebnaya, O.E. Lazebny, S.R. Khatami and G.E. Sulimova

 4 Prolactin in the Immune System 53 Lorenza Díaz, Mauricio Díaz-Muñoz, Leticia González, Saúl Lira-Albarrán, Fernando Larrea and Isabel Méndez

 5 Neuregulin-1 (Nrg1): An Emerging Regulator of Prolactin (PRL) Secretion 83 Weijiang Zhao

 6 Autocrine and Paracrine Regulation of Prolactin Secretion by Prolactin Variants and by Hypothalamic Hormones 97 Flavio Mena, Nilda Navarro and Alejandra Castilla

 7 The Effect of Physiological and Environmental Factors on the Prolactin Profile in Seasonally Breeding Animals 121 Edyta Molik, Tomasz Misztal and Dorota A. Zieba

 8 The Role of Prolactin in the Regulation of Male Copulatory Behavior 139 Toru R. Saito, Márk Oláh, Misao Terada and György M. Nagy

 9 Prolactin and Infertility 147 Gokalp Oner

 10 The Regulation of Pituitary Prolactin Secretion: Hypothalamic, Intrapituitary and Intracellular Factors and Signaling Mechanisms 167 Viktória Reinhoffer, Márk Oláh, Miklós Vecsernyés, Béla E. Tóth and György M. Nagy

 11 Prolactin Receptor Isoforms in Human Breast Cancer 195 Erika Ginsburg, Christopher D. Heger, Paul Goldsmith and Barbara K. Vonderhaar

 12 Physiological and Pathological Hyperprolactinemia: Can We Minimize Errors in the Clinical Practice? 213 Miguel Ángel Castaño López, José Luís Robles Rodríguez and Marta Robles García .

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