Prolactin (PRL)

Definition

Prolactin is a hormone produced by the anterior pituitary gland that plays a crucial role in lactation and reproductive health. It stimulates milk production in mammals after childbirth and also influences reproductive functions, including the regulation of the menstrual cycle and fertility. Prolactin levels are controlled by the hypothalamus, which secretes dopamine to inhibit its release, showcasing its connection to the hypothalamic-pituitary axis.

5 Must Know Facts For Your Next Test

1. Prolactin is not only important for milk production but also has roles in metabolism, immune response, and osmoregulation.
2. During pregnancy, prolactin levels increase significantly to prepare the mammary glands for lactation.
3. Stress can elevate prolactin levels, which may affect reproductive function and menstrual cycles.
4. Certain medications, particularly antipsychotics and antidepressants, can increase prolactin levels by blocking dopamine receptors.
5. High levels of prolactin in non-pregnant women can lead to conditions like galactorrhea (milk production) and amenorrhea (absence of menstruation).

Review Questions

• How does prolactin interact with other hormones during pregnancy and postpartum?
  • During pregnancy, prolactin levels rise significantly due to increased production by the anterior pituitary. This surge prepares the mammary glands for milk production after childbirth. Postpartum, prolactin continues to facilitate lactation by stimulating milk synthesis, while other hormones like oxytocin promote milk ejection. The interplay between these hormones is vital for successful breastfeeding.
• What is the role of dopamine in regulating prolactin secretion?
  • Dopamine acts as a key inhibitor of prolactin secretion from the anterior pituitary gland. It is produced by the hypothalamus and prevents excessive release of prolactin under normal physiological conditions. When dopamine levels decrease, prolactin release increases, which can happen during stress or certain medical conditions. This feedback loop is essential for maintaining hormonal balance within the body.
• Evaluate how elevated prolactin levels can impact reproductive health and what clinical implications this may have.
  • Elevated prolactin levels can lead to various reproductive health issues such as galactorrhea, amenorrhea, and infertility. These conditions arise because high prolactin inhibits gonadotropin-releasing hormone (GnRH), disrupting the normal menstrual cycle and reducing estrogen levels. Clinically, this may necessitate treatment options like dopamine agonists to lower prolactin levels and restore normal reproductive function. Understanding these implications is crucial for diagnosing and managing reproductive disorders.

Related terms

Lactation: The process of producing milk from the mammary glands, initiated by the secretion of prolactin after childbirth.

Dopamine: A neurotransmitter produced by the hypothalamus that inhibits prolactin secretion from the anterior pituitary.

Hypothalamic-Pituitary Axis: The system involving the interaction between the hypothalamus and the pituitary gland, which regulates various hormonal functions in the body.