Oxytocin - The Love Hormone?
by Tiffany Spudich, PharmD
brought to you by Bellevue
Pharmacy, a ProjectAWARE sponsor
Oxytocin, sometimes called the hormone of love, not only induces
uterine contractions during childbirth but is also released as a
mother nurses her baby and is responsible, at first touch, for her
feelings of attachment to the newborn. The instinct to want to cuddle
continues to intensify; hence oxytocin often also gets referred
to as the “cuddle hormone.” Oxytocin was first synthesized
in 1951 and has been prescribed to women since then to induce labor
and facilitate breast-feeding. Oxytocin means "swift birth"
But the role of oxytocin goes beyond childbirth and mother-infant
bonding. Oxytocin, found in both
men and women, has a large role in promoting enduring friendships,
marriages, and relationships. It is even suggested that it can even
promote trust among strangers. Data has shown that oxytocin reduces
anxiety levels in users and hence helps to facilitate social contact
between people. One study by Paul Zak, PhD, of Claremont University,
and colleagues found that following administration of oxytocin through
a nasal spray, study participants were more generous toward strangers
and trusted them much more than those who did not receive oxytocin.(1)
Data has also demonstrated that participants who were given an oxytocin
infusion gave significantly more money to a stranger than participants
who took a placebo.(2)
The primary conscious behavior or thought process that increases
oxytocin is caring for another. Appreciation, generous touch, gratitude,
and emotional connections with others also raise oxytocin levels.
As with a mom and her baby, oxytocin is released in the brain in
response to hugs, kisses, and caresses, as well as simple touching.
A hug prompts the release of oxytocin, leading to feelings of closeness,
sexual intimacy, and the release of more oxytocin. Oxytocin's role
in sexual response is primarily to facilitate attraction and touch
sensation, with levels increasing secondary to touch and spiking
during orgasm.(3) Orgasm generally produces a spike in the hormone
more than two times the normal level, accounting for the calming
postcoital afterglow and greater bonding.
Oxytocin has peripheral hormonal actions and also has actions in
the brain. The peripheral actions of oxytocin mainly reflect secretion
from the pituitary gland, including lactation and uterine contractions.
Oxytocin secreted from the pituitary gland cannot re-enter the brain
because of the blood-brain barrier. Instead, the behavioral effects
of oxytocin are thought to reflect release from centrally projecting
oxytocin neurons, different from those that project to the pituitary
gland. These effects include sexual arousal, maternal behavior,
bonding, and feelings such as trust and generosity.(4) One mechanism
of oxytocin is that it binds to proteins embedded in the cell membrane
of the amygdala, a ganglion of the limbic system adjoining the temporal
lobe of the brain that is involved in emotions of fear and aggression.
This binding activates neurotransmitters that inhibit cells in the
amygdala, reducing neural activity. However, the exact length of
oxytocin’s inhibitory effect is unknown. According to Ron
Stoop of the Center for Psychiatric Neurosciences at the University
of Lausanne, Switzerland, the effect of oxytocin appears to only
be short-lived.(1) This could be due to the fact that oxytocin itself
is quickly metabolized and eliminated from the body.
Experimental studies in animals, as well as case reports in humans,
suggest that oxytocin affects different aspects of sexual behavior
and has predominantly facilitating properties for sexual appetence
and performance. One double-blind, placebo-controlled study showed
that intranasally administered oxytocin leads to a marked increase
in oxytocin levels in the blood with increased secretion of epinephrine
when subjects were engaged in sexual activity in a laboratory setting.(5)
Also, one case report presented the case of treatment-resistant
male anorgasmia who was successfully treated with administration
of intranasal oxytocin during intercourse.(6)
Oxytocin may also play a role in autism and may be a treatment option
for autism’s repetitive and affiliative behaviors.(7) Two
related studies in adults, in 2003 and 2007, found that oxytocin
decreased repetitive behaviors and improved interpretation of emotions,
but these preliminary results do not necessarily apply to children.(8)
In the future, oxytocin could eventually be considered for treatment
of social disorders characterized by excessive fear, such as social
phobia, autism and post-traumatic stress disorder. However, treatments
for social disorders must help increase the person’s desire
to interact with others, not just increase their likelihood to trust.
The effects of this natural “love hormone” are amplified
by estrogen, which is one reason women often tend to be more physically
demonstrative than men and are generally affected more by touch.
It has been suggested also that stress can restrain the production
of oxytocin.(9) Drug effects on oxytocin are not well established,
but estrogen and yohimbine increase its levels and alcohol decreases
Oxytocin has been investigated in limited studies that were generally
using a small study population. Paul Zak, PhD, a neuro-economist
at Claremont University who has been directly involved with many
of the studies regarding the neural activity of oxytocin and its
influences economic decisions, says it is premature to speculate
on clinical uses of oxytocin. Many studies have only evaluated its
effects on men, and since oxytocin has a role in breastfeeding and
childbirth, it is important to determine whether the hormone has
a different effect on women.(1) This therapy is not yet specifically
indicated for treatment of autism, social disorders, or sexual responsiveness
in either gender.
Patients with congestive failure or decreased renal function are
not good candidates for oxytocin therapy, because of its propensity
to cause fluid retention. Oxytocin helps to stimulate micro-circulation,
thereby potentially increasing body temperature which can make some
patients feel warm.(9) Oxytocin can also cause headache, an increase
in blood pressure, and a decrease in heart rate. Oxytocin is destroyed
in the gastrointestinal tract, so it is generally administered by
injection, nasal spray, or sublingual dosage form. Bellevue Pharmacy
currently compounds both oxytocin sublingual tablets and oxytocin
nasal spray, which require a prescription.
M. The trust hormone: oxytocin may make you more trusting,
but is that a good thing?. 2008 Apr; www.scienceline.org accessed
PJ, Stanton AA, Ahmadi S. Oxytocin increases generosity in
humans. PLoS ONE. 2007 Nov 7;2(11):e1128.
MA, Stimmel GL. Management of and Counseling for Psychotropic
Drug-Induced Sexual Dysfunction. www.medscape.com accessed
accessed Sep 2008.
A, Heinrichs M, Schedlowski M, Kruger TH. The acute effects
of intranasal oxytocin administration on endocrine and sexual
function in males. Psychoneuroendocrinology. 2008 Mar 27;
WW, Berman DS, Peters A. Male anorgasmia treated with oxytocin.
J Sex Med. 2008 Apr;5(4):1022-4. Epub 2007 Dec 14.
JA, Hollander E (2008). Oxytocin and experimental therapeutics
in autism spectrum disorders. Prog Brain Res. 2008;170 (451–62).
A. Search for potential autism treatments turns to trust hormone.
Nat Med. 2008;14 (4): 353.
JD. Alternative treatment of fibromyalgia using an oxytocin-hormonal-nutrient
protocol to increase nitric oxide. 2000 Apr. www.helpmythyroid.com
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