Question

• Describe the roles of oxytocin and prolactin in breastfeeding

Answer 1

Role of oxytocin in breast feeding:

• Oxytocin mediates milk ejection reflex of breast feeding, where tactile receptors in and around the nipple are sensitized in the reflex.
• The afferent neural impulses are transmitted from spinal cord to brain stem via spinothalamic tract.
• In mid brain, the information reaches paraventricular nucleus of hypothalamus via collaterals.
• These fibres stimulate oxytocin secreting magnocellular neurons of hypothalamus, thus oxytocin is released for posterior pituitary and enters circulation.
• Oxytocin causes contraction of myoepithelial cells of milk-laden alveoli of mammary gland.
• Therefore, milk is forced from alveoli into the ducts and from there to mouth of the infant.
• This is an example for neurohumoral reflex.

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Role of prolactin in breast feeding:

• The primary function of prolactin is to stimulate milk synthesis and secretion.
• Prolactin secretion increases during lactation due to activation of JAK-STAT signal induction pathway which in turn stimulates formulation of transcription factors that induce DNA and mRNA synthesis.
• Increased formation of mRNA promotes specific protein synthesis in ribosomes, which in turn causes formation of casein, lipid and lactose.
• It also causes hyperplasia of breast tissue before and after puberty.
• It stimulates development of ducts and increases the lobules of alveoli of mammary glands during pregnancy.