Secretion and Function of Pituitary Prolactin in Evolutionary Perspective

Arpád Dobolyi; Szilvia Oláh; Dávid Keller; Rashmi Kumari; Emese A Fazekas; Vivien Csikós; Éva Renner; Melinda Cservenák

doi:10.3389/fnins.2020.00621

Secretion and Function of Pituitary Prolactin in Evolutionary Perspective

Front Neurosci. 2020 Jun 16:14:621. doi: 10.3389/fnins.2020.00621. eCollection 2020.

Authors

Arpád Dobolyi^{1

2}, Szilvia Oláh¹, Dávid Keller², Rashmi Kumari¹, Emese A Fazekas¹, Vivien Csikós¹, Éva Renner³, Melinda Cservenák¹

Affiliations

¹ MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary.
² Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary.
³ Human Brain Tissue Bank and Microdissection Laboratory, Semmelweis University, Budapest, Hungary.

Abstract

The hypothalamo-pituitary system developed in early vertebrates. Prolactin is an ancient vertebrate hormone released from the pituitary that exerts particularly diverse functions. The purpose of the review is to take a comparative approach in the description of prolactin, its secretion from pituitary lactotrophs, and hormonal functions. Since the reproductive and osmoregulatory roles of prolactin are best established in a variety of species, these functions are the primary subjects of discussion. Different types of prolactin and prolactin receptors developed during vertebrate evolution, which will be described in this review. The signal transduction of prolactin receptors is well conserved among vertebrates enabling us to describe the whole subphylum. Then, the review focuses on the regulation of prolactin release in mammals as we have the most knowledge on this class of vertebrates. Prolactin secretion in response to different reproductive stimuli, such as estrogen-induced release, mating, pregnancy and suckling is detailed. Reproduction in birds is different from that in mammals in several aspects. Prolactin is released during incubation in avian species whose regulation and functional significance are discussed. Little information is available on prolactin in reptiles and amphibians; therefore, they are mentioned only in specific cases to explain certain evolutionary aspects. In turn, the osmoregulatory function of prolactin is well established in fish. The different types of pituitary prolactin in fish play particularly important roles in the adaptation of eutherian species to fresh water environments. To achieve this function, prolactin is released from lactotrophs in hyposmolarity, as they are directly osmosensitive in fish. In turn, the released prolactin acts on branchial epithelia, especially ionocytes of the gill to retain salt and excrete water. This review will highlight the points where comparative data give new ideas or suggest new approaches for investigation in other taxa.

Keywords: comparative; dopamine; evolution; hypothalamus; lactation; neuroendocrinology; osmoregulation.

Publication types

Review