Which hormone is responsible for stimulating the suckling reflex during lactation?

SGPGI Nursing Officer-2023

Obstetrics & Gynecology

Easy

Appeared in: SGPGI Nursing Officer-2023

Explanation

Oxytocin is the hormone responsible for the milk ejection or 'let-down' reflex.
It is released from the posterior pituitary gland in response to the infant suckling the nipple.
Oxytocin stimulates the contraction of myoepithelial cells that line the alveoli and ducts of the mammary glands.
This contraction squeezes the milk from the alveoli into the ducts, making it available to the infant.
This reflex can also be triggered by psychological stimuli, such as the mother hearing her baby cry or thinking about her baby.

Option A: Oestrogen, along with progesterone, is high during pregnancy and helps in the development of the mammary glands but actually inhibits the action of prolactin, thereby preventing milk secretion before birth.
Option B: Prolactin is responsible for milk synthesis (production), not milk ejection. While its release is also stimulated by suckling, its primary role is to stimulate the alveolar cells to produce milk.
Option D: Galactoprotein is not a hormone. The term refers to proteins found within milk, such as casein or lactalbumin. It does not play a role in stimulating any lactation-related reflexes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of lactation, specifically the milk ejection (let-down) reflex as background academic context rather than a clinical decision trigger.
A nurse should educate new mothers that stress, anxiety, pain, and fear can inhibit the oxytocin reflex, leading to difficulty with breastfeeding. Creating a calm, comfortable, and private environment is crucial.
Promoting early and frequent breastfeeding, as well as skin-to-skin contact, helps establish both the prolactin (production) and oxytocin (ejection) reflexes, ensuring a good milk supply.
If a mother is separated from her infant, regular breast pumping (every 2-3 hours) is necessary to mimic the suckling stimulus, thereby maintaining both prolactin and oxytocin release to sustain lactation.

How to Approach the Question

First, identify the key terms in the question: 'hormone' and 'suckling reflex'. This points to the hormonal control of lactation.
Recall the two primary hormones involved in lactation: Prolactin and Oxytocin.
Differentiate their main functions. Remember the mnemonic 'P for Production' (Prolactin makes milk) and 'O for Out' (Oxytocin gets the milk out).
The question asks about the reflex stimulated by suckling that makes milk available. This is the milk ejection or 'let-down' reflex.
Connect the milk ejection reflex to its corresponding hormone, which is Oxytocin.
Evaluate the other options. Oestrogen inhibits lactation during pregnancy, and 'Galactoprotein' is not a hormone, eliminating them as possibilities.

Concept Tested & Keywords

Concept Tested: Hormonal regulation of lactation, specifically the milk ejection (let-down) reflex.
Stem keywords: hormone, suckling reflex, lactation
Lead-in keywords: responsible for stimulating

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