Hypocretin: Characteristics And Functions

Hypocretin (or orexin) is a type of exciting neuropeptide hormone ; specifically, it is a polypeptide hormone found in the posterior hypothalamus. Its functions include inducing the sensation of hunger, stimulating the state of wakefulness or alertness and promoting a positive state of mind, among others. On the other hand, having high levels of it has been related to sleep disorders such as insomnia or narcolepsy.

Some actions related to diet and lifestyle habits could increase the presence of this hormone. Thus, practices such as sunbathing, exercising, consuming foods with lactate, restricting glucose and increasing fructose, could stimulate its secretion.

Hypocretin: what is it?

Hypocretin, also called orexin, is a type of exciting neuropeptide hormone that was discovered in rat brains by two researchers, according to Sakurai et al. (1998) and De Lecea et al. (1998). Hypocretin, whose original name comes from English, hypocretin, was discovered in 1998.

It is a polypeptide neuronal hormone made up of 30 amino acids. It is located in the hypothalamus, a brain structure involved in physiological functions such as appetite, libido, and sleep regulation.

Features

Hypocretin was initially suggested to be involved in stimulating food intake (ie, hunger). This was believed because central administration of this hormone, specifically orexin-A / hypocretin-1, was found to increase food intake.

Later, they also discovered that hypocretin stimulated insomnia, energy expenditure and wakefulness. Thus, we find different functions that this hormone exerts.

Watch (alertness)

Hypocretin, or orexin, promotes alertness. Recent studies indicate that one of its relevant functions is to integrate the metabolic influences of the circadian rhythm and sleep debt, in order to determine whether an animal should be asleep or awake and active.

Specifically, hypocretin would strongly excite various brain nuclei, with important roles in insomnia (dopamine, acetylcholine, norepinephrine systems …). On the other hand, according to a study by Lin et al. (1999), an orexin / hypocretin receptor mutation causes canine sleep disorders, such as narcolepsy.

Eating of food

Hypocretin also fulfills the function of stimulating or increasing the craving for food, or what is the same, the craving. In this sense, it interacts with substances that promote its production. Specifically, hypocretin acts by increasing its expression, locating in the arcuate nucleus of the hypothalamus.

On the other hand, some animal studies show that low levels of orexin cause obesity, and that this occurs even when consuming fewer calories.

Alzheimer disease?

A study by Kang et al. (2009) linked hypocretin to Alzheimer’s disease. According to the study, the expression of the Beta-amyloid protein (a peptide that typically appears in Alzheimer’s), increases during the day and falls at night, and all this is controlled precisely by hypocretin.

It has been found that sleep deprivation could be the cause of the development of Beta-amyloid plaques. The same study also suggests that maintaining appropriate periods of sleep or wakefulness could prevent Alzheimer’s disease.

Influence on good mood

Hypocretin is not only related to physiological functions, but also to emotional ones. Thus, high levels of hypocretin are related to a positive mood, as well as a feeling of happiness.

Anxiety and addictions

It is believed that low levels of hypocretin would influence the urge to smoke and drink alcohol, especially in cases of addiction. In addition, its presence has also been associated with brain reward mechanisms. It has been observed how an abnormally high activity of the same leads to states of anxiety, which could make the person relapse to the consumption of toxins.

How to stimulate hypocretin?

Some actions or lifestyle habits can increase the presence of hypocretin in our body. Among them are:

• Sunbathing – Bright lights, like sunlight, increase hypocretin levels.
• Exercise : the acidification of the blood that occurs when exercising, increases the excitability of hypocretin.
• Consume foods with lactate : lactate regulates hypocretin, while increasing our energy.
• Restrict glucose and increase fructose : elevated glucose levels can block the activity of orexin neurons.

In relation to the last mentioned, some foods that contain glucose (healthy) are: pasta, whole wheat bread, potatoes or legumes. On the other hand, we find unhealthy glucose foods: white bread, salty snacks and fried foods, among others.

As we have seen, hypocretin is a hormone that is related to multiple functions, both physiological and psychological. Many have dubbed it “the hormone of good humor”, and in this sense, it has been associated with positive emotional states. It is responsible for regulating emotions, mood and sleep / wake cycles, and is also linked to learning processes.

Finally, altered levels of it are related to sleep disorders, obesity and even Alzheimer’s disease.