The Element
Summer 2022
levels of oxytocin increase in times of bonding between parent and child such as skin to skin contact, in childbirth, and whilst hugging. It is a protein made of nine amino acids (a nonapeptide) in the sequence: cysteine-tyrosine-isoleucine-glutamine-asparag ine-cysteine-proline-leucine-glycine-amide. Oxytocin is made in neurosecretory cells, in the hypothalamus, and is released into the blood from the pituitary gland. After birth, suckling by the baby is relayed by spinal nerves to the hypothalamus. The stimulation causes neurons to secrete oxytocin in intermittent bursts. This triggers the milk ejection reflex also known as ‘let down’. In this scenario, oxytocin causes the cells around the milk-filled alveoli to contract and squeeze milk out through the milk ducts to allow the baby to feed.
The biochemistry behind Breastfeeding After a person has given birth, one of the first natural maternal instincts is to hold the baby up to their chest so it can do one of the main things required for human survival - to eat. The breast milk produced contains supplements to nourish and give the newborn baby what it needs to survive. However, the body must first find a way to produce and release it. This process is facilitated by the hormones prolactin and oxytocin.
Prolactin is a polypeptide hormone made of 199 amino acids, and is produced by the pituitary gland in the brain. In humans, the prolactin molecule is arranged in a single chain of amino acids, with three intramolecular disulfide bonds between six cysteine residues (another type of amino acid). It starts to be released during the end of pregnancy, but high levels of oestrogen and progesterone counteract its effects. After birth, the levels of oestrogen and progesterone drop rapidly which allows prolactin to stimulate the production of breast milk. This is known as lactogenesis. Prolactin causes the lactocytes (the milk producing cells on the alveoli in the breasts) to take proteins, fats and sugars from the blood supply in order to produce breast milk. Oxytocin is often known as the ‘love drug’ or the ‘cuddle hormone’ and is associated with empathy, trust, and relationship-building. The 8
