Prolactin (PRL)

Prolactin (PRL)

Prolactin (PRL) is a protein hormone primarily produced by the lactotrophic cells of the anterior pituitary gland. It plays a crucial role in lactation and has various functions in both males and females beyond its well-known role in milk production.

Functions of Prolactin

1. Lactation: The primary function of prolactin is to stimulate breast milk production after childbirth. During pregnancy, prolactin levels rise to prepare the mammary glands for lactation. After delivery, suckling by the infant triggers further prolactin release, promoting milk synthesis and secretion.
2. Reproductive Health: Prolactin influences reproductive functions by inhibiting gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus. Elevated prolactin levels can disrupt menstrual cycles in women, leading to conditions such as oligomenorrhea (irregular periods) or amenorrhea (absence of menstruation). In men, high prolactin levels can lead to decreased testosterone production, resulting in symptoms like reduced libido and erectile dysfunction.
3. Other Functions: Beyond reproduction, prolactin has roles in:

• Immune Regulation: It is involved in immune system modulation and can influence immune responses.
• Metabolism: Prolactin affects fat metabolism and may play a role in regulating body weight.
• Behavioral Effects: There is evidence suggesting that prolactin may influence maternal behaviors and stress responses.

Regulation of Prolactin Secretion

Prolactin secretion is primarily regulated by dopamine, which inhibits its release from the pituitary gland. Other factors that can stimulate prolactin release include:

• Suckling: The most significant stimulus for prolactin release.
• Stress: Physical or emotional stress can increase prolactin levels.
• Estrogens: High levels of estrogen during pregnancy also stimulate prolactin production.

Normal Prolactin Levels

Prolactin levels vary based on gender and physiological conditions:

• Women (non-pregnant): 2-30 ng/mL
• Men: 2-18 ng/mL
• Pregnant Women (3rd trimester): 10-210 ng/mL

Disorders Related to Prolactin

1. Hyperprolactinemia: Elevated levels of prolactin can lead to symptoms such as irregular menstrual cycles, infertility, galactorrhea (unexpected milk production), and decreased libido in both genders. Common causes include pituitary tumors (prolactinomas), certain medications, and hypothyroidism.
2. Hypoprolactinemia: This condition is rare and characterized by low prolactin levels, which can result in insufficient milk production postpartum and may be associated with pituitary dysfunction.

Conclusion

Prolactin is a multifaceted hormone with essential roles in lactation and reproductive health. Understanding its functions and regulation is important for diagnosing and managing conditions related to hormonal imbalances.

References

1. Ada Health. (2024). Prolactin: Role in Reproductive Health. Retrieved from Ada
2. BYJU’S Biology. (n.d.). Prolactin Hormone – Functions, Disorders and Prolactin Levels. Retrieved from BYJU’S
3. PubMed Central. (2024). Current Insights in Prolactin Signaling and Ovulatory Function. Retrieved from PMC
4. Britannica. (2024). Prolactin | Hormone Regulation & Role in Reproduction. Retrieved from Britannica
5. PubMed. (2000). Prolactin: Structure, Function, and Regulation of Secretion. Retrieved from PubMed