Ubiquitous nutrients suppress appetite and promote movement (Non-essential amino acids)

Researchers show that non-essential amino acids act as appetite suppressants and promote the urge to move.

A protein-rich diet can help people lose weight. Researchers have now demonstrated a new mechanism by which the building blocks of proteins curb appetite. Specifically, it involves non-essential amino acids.

Of the 21 amino acids our bodies require, there are nine they are unable to produce on their own. They are called essential amino acids. Because we must obtain these through our diet, they have long been the focus of nutrition research. The other 12 amino acids are considered non-essential. The body can produce them itself by altering other molecules.

It has been known that both essential and non-essential amino acids can suppress appetite. Now, a group of researchers have shown that the non-essential amino acids influence the brain in a way that curbs appetite and promotes exercise.

The researchers first fed mice either a mixture of various non-essential amino acids or a sugar solution with the same amount of calories (control group). Both groups of mice were then allowed to drink a milkshake, which they normally love. While the control group drank copious amounts of it, the mice that had been fed non-essential amino acids avoided theirs. Instead, they went around their enclosure in search of alternative sustenance.

This mechanism is likely rooted in evolutionary history. "Today, we have sufficient access to all nutrients, and we have plenty of time for eating. In prehistoric times, when this mechanism developed, that was likely not the case," says Paulius Viskaitis, a postdoc.

Viskaitis stresses that the results are transferable to humans and other animals, as this mechanism affects a region of the brain that is very old in terms of evolutionary history and occurs equally in all mammals and many other vertebrates.

Per the article:

“With additional experiments, the researchers were able to decode the underlying mechanism, in which specialized nerve cells in the brain—orexin neurons—play the main role. Proteins that the mice take in through food are broken down in the gut into their amino acids, which then enter the bloodstream.

From there, the blood transports them to the brain. The orexin neurons in the hypothalamus have receptors that specifically recognize the non-essential amino acids. In response, they initiate a neural circuit that produces the described behavioral changes.”

Per Wiki:

“Orexin, also known as hypocretin, is a neuropeptide that regulates arousal, wakefulness, and appetite. The most common form of narcolepsy, type 1, in which the individual experiences brief losses of muscle tone (cataplexy), is caused by a lack of orexin in the brain due to destruction of the cells that produce it.

There are only 10,000–20,000 orexin-producing neurons in the human brain, located predominantly in the perifornical area and lateral hypothalamus. They project widely throughout the central nervous system, regulating wakefulness, feeding, and other behaviors. There are two types of orexin peptide and two types of orexin receptor.

Orexin was discovered in 1998 almost simultaneously by two independent groups of researchers working on the rat brain. One group named it orexin, from orexis, meaning “appetite” in Greek; the other group named it hypocretin, because it is produced in the hypothalamus and bears a weak resemblance to secretin, another peptide. Officially, hypocretin (HCRT) is used to refer to the genes and transcripts, while orexin is used to refer to the encoded peptides. There is considerable similarity between the orexin system in the rat brain and that in the human brain.”

The lateral hypothalamus (LH), also called the lateral hypothalamic area (LHA), contains the primary orexinergic nucleus within the hypothalamus that widely projects throughout the nervous system; this system of neurons mediates an array of cognitive and physical processes, such as promoting feeding behavior and arousal, reducing pain perception, and regulating body temperature, digestive functions, and blood pressure, among many others.

Clinically significant disorders that involve dysfunctions of the orexinergic projection system include narcolepsy, motility disorders or functional gastrointestinal disorders involving visceral hypersensitivity (e.g., irritable bowel syndrome), and eating disorders.

The neurotransmitter glutamate and the endocannabinoids (e.g., anandamide) and the orexin neuropeptides orexin-A and orexin-B are the primary signaling neurochemicals in orexin neurons; pathway-specific neurochemicals include GABA, melanin-concentrating hormone, nociceptin, glucose, the dynorphin peptides, and the appetite-regulating peptide hormones leptin and ghrelin, among others. Notably, cannabinoid receptor 1 (CB1) is colocalized on orexinergic projection neurons in the lateral hypothalamus and many output structures, where the CB1 and orexin receptor 1 (OX1) receptors form the CB1–OX1 receptor heterodimer.”

I Highlight...(The cause of the munchies when you smoke pot!)

“cannabinoid receptor 1 (CB1) is colocalized on orexinergic projection neurons in the lateral hypothalamus”

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