What is the Difference Between Prolactin and Oxytocin Hormone

The key difference between prolactin and oxytocin hormone is that prolactin hormone is a protein hormone responsible for milk production, while oxytocin hormone is a protein hormone responsible for milk ejection reflex and uterine contraction during childbirth.

The hormones produced by endocrine glands are either proteins or steroids. None of the hormones have any enzymatic function. But they function as chemical messengers. Protein hormones are hormones whose molecules are either peptides or proteins. When a protein hormone binds to a receptor on the cell surface, a second messenger appears in the cytoplasm triggering signal transduction that leads to specific cellular responses. Some examples of protein hormones are ACTH, angiotensin, calcitonin, prolactin, oxytocin, FSH, LH, rennin, TSH, and vasopressin. Prolactin and oxytocin hormones are two protein hormones.

CONTENTS

1. Overview and Key Difference
2. What is Prolactin Hormone  
3. What is Oxytocin Hormone
4. Similarities – Prolactin and Oxytocin Hormone
5. Prolactin vs Oxytocin Hormone in Tabular Form
6. Summary – Prolactin vs Oxytocin Hormone

What is Prolactin Hormone?

Prolactin hormone is a protein hormone synthesized by lactotrophs in the anterior pituitary.  It is also secreted from the pituitary gland in response to eating, estrogen treatment, mating, ovulation, and nursing. Prolactin plays a role in enabling mammals (usually females) to produce milk. This process is known as lactation. This protein can also trigger lactation in birds. Prolactin is influential in over 300 separate processes in various vertebrates. Moreover, prolactin plays an essential function in metabolism, regulation of the immune system, and pancreatic development. This hormone was first discovered in non-human animals around 1930 by Oscar Riddle. The presence of prolactin in humans was confirmed in 1970 by Henry Friesen. This peptide hormone is encoded by the PRL gene.

In addition to stimulating milk production, prolactin also stimulates the proliferation of oligodendrocyte precursor cells which differentiate into oligodendrocytes later. Furthermore, other functions of this hormone include contributing to pulmonary surfactant synthesis of fetal lungs at the end of the pregnancy, immune tolerance of fetus by the maternal organism during pregnancy, and promoting neurogenesis in maternal and fetal brains. In other vertebrates like fish, it is involved in controlling water and salt balance.

What is Oxytocin Hormone?

Oxytocin hormone is a protein hormone produced by the hypothalamus and released by the posterior pituitary. It is responsible for milk ejection reflex and uterine contraction during childbirth. Oxytocin is released into the blood as a hormone in response to sexual activity and during labor. This hormone also plays a role in bonding with the baby and milk production.

Oxytocin hormone is available in pharmaceutical form as well. The production of oxytocin is regulated by a positive feedback mechanism. It means its initial release stimulates further production and release of oxytocin. This protein is encoded by the OXT gene. It is a nano peptide. Moreover, the oxytocin hormone was discovered in 1909 by Sir Henry H. Dale.

What are the Similarities Between Prolactin and Oxytocin Hormone?

• Prolactin and oxytocin hormones are two protein hormones.
• Both hormones are peptides made up of amino acids.
• These hormones are present in humans as well as other vertebrates.
• Both hormones are present in females as well as males.

What is the Difference Between Prolactin and Oxytocin Hormone?

Prolactin hormone is a protein hormone responsible for milk production, while oxytocin hormone is a protein hormone responsible for milk ejection reflex and uterine contraction during childbirth. Thus, this is the key difference between prolactin and oxytocin hormone. Furthermore, prolactin hormone is encoded by the PRL gene, while oxytocin hormone is encoded by the OXT gene.

The below infographic presents the differences between prolactin and oxytocin hormone in tabular form for side by side comparison.

Summary – Prolactin vs Oxytocin Hormone

Prolactin and oxytocin hormones are two protein hormones. Prolactin is synthesized by lactotrophs in the anterior pituitary and released from the pituitary gland. On the other hand, oxytocin is synthesized by the hypothalamus and released from the posterior pituitary. Moreover, prolactin hormone is responsible for milk production, while oxytocin hormone is responsible for milk ejection reflex and uterine contraction during childbirth. So, this summarizes the difference between prolactin and oxytocin hormone.

Reference:

1. “Prolactin.” You and Your Hormones.
2. Magon, Navneet, and Sanjay Kalra. “The Orgasmic History of Oxytocin: Love, Lust, and Labor.” Indian Journal of Endocrinology and Metabolism, Medknow Publications.

Image Courtesy:

1. “Lactating Breast Structure” By Rajendra prabhune – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “OXT and AVP synthesized in the neurons located in the PVN and SON”  By Mauricio Aspé-Sánchez, Macarena Moreno, Maria Ignacia Rivera, Alejandra Rossi and John Ewer – Aspé-Sánchez M, Moreno M, Rivera M-I, Rossi A and Ewer J (2016) Oxytocin and Vasopressin Receptor Gene Polymorphisms: Role in Social and Psychiatric Traits. Front. Neurosci. 9:510. doi: 10.3389/fnins.2015.00510 (CC BY 4.0) via Commons Wikimedia