Oxytocin

What is oxytocin?

Oxytocin is a hormone with many functions. It can create a let-down, cause the uterus to contract, and help start the bonding process. It is made in the brain and stored in the pituitary gland, under the brain. When a mother breastfeeds, oxytocin is released. Some studies have found that oxytocin may suppress the appetite and reduce anxiety, depression, and the risk of drug dependency.

A) Describing oxytocin

Oxytocin is a hormone that is made in a part of the brain called the hypothalamus and is composed of amino acids. It is stored in the back half of the pituitary gland, under the brain.

Oxytocin is released in pulses when the pituitary gland receives signals from the brain. In the mother, these signals can be caused by breastfeeding, a baby's crying, or even by thinking about the baby. Compared to breastfeeding, bottle-feeding does not create a significant oxytocin release (Whitley 2020). The release of oxytocin can be reduced if a mother is in pain or very stressed.

Oxytocin is also present in breast milk allowing it to support the baby’s well-being and development.

Testing oxytocin blood levels is not generally helpful in identifying the cause of a low milk supply.

B) What oxytocin does

Oxytocin has many functions and can (Leppanen 2017; Magon 2011; Misrani 2017):

  • Pass through the placenta and help protect the baby’s brain from low oxygen levels during delivery.
  • Cause the uterus to contract during labour and in the weeks after delivery.
  • Create a let-down.

After delivery, many mothers experience painful contractions of the uterus while breastfeeding. This is a sign that the baby is inducing a let-down in the mother by breastfeeding effectively. These contractions are beneficial as they work to shrink the uterus back to its pre-pregnant size, expel any unwanted pieces of placenta, and limit uterine bleeding.

Oxytocin is often called the “love hormone,” as it has been shown to:

  • Help start the bonding process.
  • Create a positive attitude toward others.
  • Increase romantic attachment.

Studies have reported other possible functions including (Viero 2010):

  • Normal suppression of appetite (Atasoy 2012)
  • Reduction in the risk of drug dependency
  • Reduction of depression (Thul 2020)
  • Reduction of stress and anxiety (Jones 2017)
  • Enhancement of wound healing
  • The prevention of autism (Wermter 2010; Yang 2017)

References

Atasoy D, Betley JN, Su HH, et al. Deconstruction of a neural circuit for hunger. Nature. 2012;488 (7410): 172–7

Jones C, Barrera I, Brothers S, et al. Oxytocin and social functioning. Dialogues Clin Neurosci. 2017 Jun;19(2):193-201 
 
Leppanen J,  Ng KW,  Tchanturia K, et al. Meta-analysis of the effects of intranasal oxytocin on interpretation and expression of emotions. Neurosci Biobehav Rev.  2017 Jul;78:125-144
 
Magon N, Kalra S. The orgasmic history of oxytocin: Love, lust, and labor. Indian J Endocrinol Metab. 2011 Sep;15 Suppl 3:S156-61
 
Misrani A,  Tabassum S,  Long C. Oxytocin system in neuropsychiatric disorders: Old concept, new insights. Sheng Li Xue Bao.  2017 Apr 25;69(2):196-206

Thul TA, Corwin EJ, Carlson NS, et al. Oxytocin and postpartum depression: A systematic review. Psychoneuroendocrinology. 2020 Jul 6;120:104793

Viero C, Shibuya I, Kitamura N, et al. REVIEW: Oxytocin: Crossing the bridge between basic science and pharmacotherapy. Version 2. CNS Neurosci Ther. 2010 Oct;16(5):e138-56
 
Wermter AK, Kamp-Becker I, Hesse P, et al. Evidence for the involvement of genetic variation in the oxytocin receptor gene (OXTR) in the etiology of autistic disorders on high-functioning level. American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics. 2010; 153B (2): 629–39

Whitley J, Wouk K, Bauer AE, et al. Oxytocin during breastfeeding and maternal mood symptoms. Psychoneuroendocrinology. 2020 Mar;113:104581

Yang S,  Dong X,  Guo X, et al. Serum Oxytocin Levels and an Oxytocin Receptor Gene Polymorphism (rs2254298) Indicate Social Deficits in Children and Adolescents with Autism Spectrum Disorders. Front Neurosci. 2017 Apr 21;11:221