Oxytocin: What is love?

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This Valentine’s day, you might be feeling extraordinarily giddy and happy with your main squeeze, or possibly a little irate or gloomy about not having someone to give candy and flowers. In any case, the concept of love has probably crossed your mind at some point today. What is love? Is there such a thing as “true love?” Will there ever be a person willing to put up with my annoying habits? The answer to these questions could lie in a hormone called oxytocin that is responsible for many of the emotions we feel associated with the word love.

What does oxytocin do?

Oxytocin is the reason we feel butterflies when the cute guy or girl across the room smiles at us. It is responsible for the warm fuzzy feelings we get when someone hugs us. It is also to blame for the sorrow and despair we feel when trust is broken.

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Oxytocin is also the reason for the strong maternal bond that humans have with their children. It is released during childbirth and breastfeeding. Most, if not all of oxytocin’s intended functions are related to human reproduction.

Oxytocin also has many medical uses because of its uplifting properties. It is sold synthetically under the name Pitocin to treat depression and to induce labor. Recently it has also been explored to treat autism after a study showed that people with autism displayed lower levels of the hormone than people without autism.

Oxytocin is one of the many hormones secreted by the pituitary gland. Hormones are produced in glands to tell your body to perform certain activities like digestion, growth, mood, and in the case of oxytocin, reproduction. When we do something that our bodies like, our brains release dopamine to make us feel good and tell us we should do it again. Dopamine is a neurotransmitter that can influence addictive behavior, outlined in last week’s post on sugar.

In the case of love and sex, dopamine triggers the release of oxytocin into the blood which binds with oxytocin receptors. When oxytocin binds it causes a strong bond to the person who caused the dopamine to be released (usually a sexual partner or baby). New research suggests that oxytocin is the reason that humans display monogamous behaviors in addition to maternal bonding. The video below does a great job of describing the relationship between love and the brain.

The reason for “til’ death do we part”

New studies have shown that oxytocin is responsible for monogomous relationship behavior in humans. Humans are one of the few species that exhibit monogamous behavior because from the standpoint of evolution it is advantageous for male species to spread their genes to as many partners as possible. Very little is known about the neurobiological reasons for humans to stay loyal to one sexual partner.

Another animal exhibiting monogamous behavior is the prairie vole. Studies on prairie voles have shown that oxytocin is released in the brain after mating. The voles form a partner bond with their mate after the interactions of dopamine and injected oxytocin. On the contrary, when female prairie voles were injected with an oxytocin antagonist they displayed no affection toward their male counterpart. 

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In a study done with 20 men, data revealed that oxytocin contributes to romantic connections by making them perceive their partner as more attractive than other women. After oxytocin treatment, the men perceived their partner to be increasingly attractive, displayed by a rise in neuroactivity. However, when shown pictures of unfamiliar women, there was no increase in neuroactivity. In other words, the pleasure areas of the brain lit up when they saw a picture of their partner, while pictures of the unfamiliar women showed suppressed feelings of pleasure.

Why would monogamy be beneficial to humans? Scientists think that the reason humans display pair bonding to their sexual partners is due to the decay in oxytocin over time in a relationship. Monogamy evolves in species because of the amount of work it takes to nurture offspring. Human offspring are more difficult to raise than other animals, so it took the work of two parents to raise a child when humans were evolving. Luckily in modern times, we have more access to resources to make raising children a possibility with one parent.

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Oxytocin is a strong and wonderful chemical. It makes us feel human. Whether or not you have a valentine today, go out there and make some oxytocin! Hug a friend, spend time with family, and get those feel-good fuzzies. Here’s to love!

Thanks for reading, and cheers to your brain!

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References:

Lee, Heon-Jin, Abbe H. Macbeth, and Jerome H. Pagani. "Oxytocin: the great facilitator of life." Progress in neurobiology 88.2 (2009): 127-151.

Scheele, Dirk, et al. "Oxytocin enhances brain reward system responses in men viewing the face of their female partner." Proceedings of the National Academy of Sciences 110.50 (2013): 20308-20313.

Sugar Addiction: The Sweet Enemy of the Waistband

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Have you ever joked about being addicted to sugar? It may not be far from the truth. Researchers have recently shown that sugar consumption leads to effects similar to those of drug abuse, classifying it as an addictive substance. The amount of sugar in the average American diet has increased dramatically in recent years to nearly double the recommended amount. Understanding how sugar affects our brains and bodies may help us find a way to better fight obesity, which is the leading cause of preventable death in the U.S.

Sugar consumption in the U.S. is nearly 10 times what it was 200 years ago and continues to rise. (source)

If you watch Breaking Bad or any other show or movie portraying drug addiction, this behavior is characterized by the extreme danger drug addicts put themselves and their loved ones in to obtain more of the drug.

Addiction is characterized several by symptoms:

• Bingeing: the increase in consumption of a substance with a large intake at once (when you accidentally ate that whole box of Thin Mints®).

• Withdrawal: when deprived of the substance symptoms like anxiety and physical pain persist (ever gotten a headache because you didn’t drink your morning Joe?).

• Craving: an increase in desire and effort to obtain a substance that has been deprived (driving across town at 4am to the only 24 hour grocery store to get a pint of Ben and Jerry’s® because you can’t wait until tomorrow).

• Sensitization: is another word for a gateway drug; for instance those who drink alcohol are more likely to smoke cigarettes at the same time.

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When researchers fed the equivalent amount of sugar in a soft drink to rats, they exhibited each of the defining addictive behaviors. The rats consumed a large amount of the sugar at one time (bingeing), displayed anxious behavior when the sugar solution was removed (craving), and showed signs of withdrawal when the sugar solution was not available. In another study, a group of rats that were previously exposed to cocaine showed a preference to sugar over cocaine, a sign of sensitization.

Why do we develop an addiction to sugar?

Our ancestors’ survival was dependent on eating a lot when food was available because they didn’t know when their next meal would be. As a result, we evolved to respond certain ways to foods with a lot of calories like fat and sugar, like feeling compelled to eat sweets. This trait was advantageous in keeping humans alive in early days, but the mass production and availability of food in our lives has turned it into a disadvantage.

What is actually happening in our brains that cause us to feel this way? Understanding why our brains tell us to continue eating massive amounts of sugar without stopping can help us adapt our eating habits to the 21^st century living style and help curb the “obesity epidemic.”

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When sugar is consumed, our brains release a chemical called dopamine. When you do something to release dopamine, your brain tells you to do it again because it feels good. Dopamine is classified as a neurotransmitter, meaning brain cells send it to tell other brain cells what to do. Dopamine is associated with reward-motivated behavior, which is why it feels good when it is released. Addictive drugs like heroine and opium activate dopamine containing brain cells, which tells the body to keep using them.

While you eat food, dopamine is released and dopamine levels initially spike but tend to return to normal when you continue eating the same food for each meal. This is why you stop wanting to eat the same meal every day of the week. The reason for this is so that you can attain a balanced diet with a variety of nutrients. By seeking a variety of tastes and flavors, you are likely to get essential vitamins and minerals from various sources.

Sugar, on the other hand, does not regulate the release of dopamine the same way as most foods, so you continue to want more of it in a kind of domino effect (and without it you develop cravings and withdrawal symptoms). This is especially true for individuals who eat more than the recommended amount of sugar (average Americans). Substances that produce this domino-like effect are frequently abused and include drugs like heroine and cocaine.

How can we fight sugar addiction?

Even though sugar causes addictive behavior in people, it doesn’t usually negatively alter behavior. In fact, in certain instances it can be beneficial for decision making and self-control. This is why you can’t be arrested for eating too many doughnuts before you drive (Homer would be behind bars for sure).

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A diet consisting of more processed food has drastically increased the amount of sugar we are consuming. Added sugar is hidden in many common food products, like ketchup, pizza sauce, Sriracha®, peanut butter, and other unsuspecting condiments. Worse yet, the sugar in processed foods is usually in the form of high-fructose corn syrup, which is shown to contribute to an increase in body weight more than other forms of sugar. The graphic below shows how much sugar the average American is consuming.

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Recognizing which products have added sugar to them and understanding exactly how sugar is contributing to poor health might motivate people to stop eating so much of it. Perhaps better labeling and elementary school educational programs would be beneficial.

The bottom line is, only you can control your sugar consumption. Eating less processed foods and drinking less sugary beverages will not only make you look and feel better, but you will also stop making those midnight ice cream runs... I can toast to that!

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Thanks for reading, and cheers to your brain!

Like my Facebook page to stay up to date on weekly blog posts and other science findings!

References:

Avena, Nicole M., Pedro Rada, and Bartley G. Hoebel. "Evidence for sugar addiction: behavioral and neurochemical effects of intermittent, excessive sugar intake." Neuroscience & Biobehavioral Reviews 32.1 (2008): 20-39.

Ahmed, Serge H., Karine Guillem, and Youna Vandaele. "Sugar addiction: pushing the drug-sugar analogy to the limit." Current Opinion in Clinical Nutrition & Metabolic Care 16.4 (2013): 434-439.