Hormones are chemical messengers that are secreted directly into the blood, which carries them to organs and tissues of the body to exert their functions.  

They control growth, metabolism, behavior, sleep, lactation, stress, mood swings, sleep–wake cycles, the immune system, mating, fighting, fleeing, puberty, parenting and sex. They aim to get us back to normal when things are out of whack and can be the cause of commotion, too.

There are many types of hormones that act on different aspects of bodily functions and processes.  Scientists continue to learn more about them, and current research has uncovered new information about one hormone in particular.  

Prior to these studies oxytocin was primarily used to initiate and improve uterine contractions in childbirth. New studies have shown that oxytocin can affect maternal behavior, social bonding and even sexual pleasure.  Moreover, oxytocin can make us more sympathetic, supportive and open with our feelings such that it extends into maintaining romantic relationships. There has also been research to find out whether oxytocin can correct some of the interpersonal deficiencies brought on by autism.

Books have been written extolling the properties of oxytocin, calling it the hormone of calm, love, trust, passion and intimacy. Along with dopamine, endorphin and serotonin it has been described as one of the happy chemicals. Oxytocin is even being tested as an anti-anxiety drug. One website gives 10 reasons why oxytocin is the most amazing molecule in the world, perhaps not an exaggeration.  



Oxytocin

The word “oxytocin” was derived from Greek oxys, and tokos, meaning quick birth, after its uterine-contracting properties were discovered by British pharmacologist Sir Henry Hallett Dale in 1906. The nine-amino-acid sequence in its structure was discovered by Vincent du Vigneaud and by Tuppy in 1953 and synthesized biochemically soon thereafter by du Vigneaud that same year.  

Oxytocin is a very abundant neuropeptide, exerting a wide spectrum of central and peripheral effects as a neurohormone, neurotransmitter or neuromodulator. It is produced mainly in the hypothalamus, where it is either released into the blood via the posterior lobe of the pituitary gland, or to other parts of the brain and spinal cord, where it binds to oxytocin receptors to influence behavior and physiology. The behavioral effects are thought to reflect release from centrally projecting oxytocin neurons, different from those that project to the pituitary gland.  

Oxytocin receptors are expressed by neurons in many parts of the brain and spinal cord. Peripheral actions mainly reflect secretion from the pituitary gland and are responsible for the stimulatory effects on the mammary glands (the hormone activates  contractions of muscular cells around the milk glands) and the uterus.  

Potential Uses

The excitement over oxytocin began in the 1990s, when researchers discovered that breastfeeding women are calmer in the face of exercise and psychosocial stress than bottle-feeding mothers. More recent literature has shown a number of other uses. Oxytocin levels are high under stressful conditions, such as social isolation and unhappy relationships.

New investigations show that oxytocin can make us more sympathetic, supportive and open with our feelings. These findings have led some researchers to investigate whether oxytocin can be used in couples therapy.  Oxytocin levels increase during a couple’s period of falling in love and it also correlated with the longevity of a relationship. A recent study was the first to assess whether people with variations in the their oxytocin receptor gene have a harder time maintaining romantic relationships than those who do not. The researchers found that women with a specific variation weren’t as close to their partners as women without it. These women were more likely to report having had a marital crisis. Although it is not known how this variation affects the oxytocin system, it may result from fewer oxytocin receptors in the brain. People with fewer receptors would be less sensitive to the hormone’s effects.

Oxytocin appears to play a dual role in triggering or reducing anxiety, depending on the social context. A recent study has linked oxytocin to social stress and its ability to increase anxiety and fear in response to future stress. Oxytocin appears to strengthen negative social memory and future anxiety by triggering an important signaling molecule that becomes activated for several hours after a negative social experience. Experiments with mice have established that oxytocin is essential for strengthening the memory of social interactions and that it increases fear and anxiety in future stressful situations.

Individuals with autism show altered face processing and brain activations to facial stimuli. In healthy adults, oxytocin promotes both and modulates brain activity. Magnetic resonance imaging has shown that a single intranasal dose of oxytocin increases amygdala activity in response to facial stimuli in autistic adults. This suggests that oxytocin might be used as a treatment modality. (Individuals with autism fail to recognize faces and to integrate facial expressions with emotions caused by impaired social cognitive abilities.)

Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels.  Eclectic Science, the title of his column,  will touch on famed doctors and scientists, human senses, aging,  various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at maxsherman339@gmail.com.