Secretion and Function of Pituitary Prolactin in Evolutionary Perspective

Area of Science:

• Comparative endocrinology
• Evolutionary biology
• Physiology

Background:

• Prolactin is an ancient vertebrate hormone with diverse functions, secreted by the pituitary gland.
• Its roles in reproduction and osmoregulation are well-established across various species.
• Vertebrate evolution saw the development of different prolactin types and receptors with conserved signaling pathways.

Purpose of the Study:

• To provide a comparative description of prolactin, its secretion, and hormonal functions across vertebrates.
• To highlight the reproductive and osmoregulatory roles of prolactin.
• To discuss the evolution of prolactin and its receptors and their conserved signal transduction.

Main Methods:

• Comparative review of existing literature on prolactin across vertebrate taxa.
• Focus on reproductive and osmoregulatory functions.
• Detailed examination of prolactin regulation in mammals and osmoregulation in fish.

Main Results:

• Prolactin exhibits diverse reproductive functions in mammals (e.g., estrogen-induced release, pregnancy, suckling) and birds (incubation).
• Prolactin is crucial for osmoregulation in fish, aiding adaptation to freshwater by retaining salt and excreting water.
• Conserved signal transduction pathways of prolactin receptors facilitate a subphylum-wide understanding.

Conclusions:

• Comparative analysis of prolactin provides insights into its evolution and diverse functions across vertebrates.
• Further investigation into prolactin's roles in reptiles and amphibians is warranted.
• Understanding prolactin's comparative physiology offers new avenues for research in various taxa.