Taste Sensations: Sixth Sought

Plus, what drives your appetite?

Is there a sixth basic taste?

In addition to sweet, salty, sour, bitter and umami, the tongue might also detect ammonium chloride as a basic taste. Ammonium has a unique and strong taste, a combination of bitter, salty, and a little sour. Ammonium chloride is a popular ingredient in some Scandinavian candies.

The otopetrin-1 (OTOP1) protein receptor, linked to sour taste, is activated by ammonium chloride. [The otopetrin family is a group of proteins that were first identified based on their essential role in the vestibular system.] It resides within cell membranes, forming a channel, moving hydrogen ions in/out of the cell. Extracellular NH4Cl evokes large dose-dependent inward currents in HEK-293 cells that express murine OTOP1 (mOTOP1), human OTOP1 and other species variants of OTOP1; these correlate with its ability to alkalinize the cell cytosol. Ammonium in solution is in equilibrium with ammonia, which acts like a Brønsted-Lowry base: H30+ + NH3 < - > NH4+ + H2O. The NH3 gas diffuses across the cell membranes, and once within the cytosol, regenerates NH4+, thereby reducing the concentration of intracellular H+.

Salty liquorice, salmiak liquorice or salmiac liquorice, is a variety of liquorice flavoured with the ingredient "salmiak salt" (sal ammoniac; ammonium chloride), and is a common confection found in the Nordic countries, Benelux, and northern Germany.

Appetite’s Urges

Jet-Lag will make you fat. When the body's biological clock is disrupted, the hormones responsible for regulating appetite are disordered. Circadian rhythm misalignment alters the brain's regulation of hormones controlling hunger, compromising metabolic health.

Altered expression of hypothalamic feeding regulating neuropeptide genes during out-of-phase glucocorticoid exposure. a Schematic showing analyzed brain regions of the arcuate nucleus (ARC) and lateral hypothalamic area (LHA) (schematic adapted from image taken from rat brain atlas). b Representative digital images of ISHH of Npy, Agrp, Pmch, Pomc and Cartpt. Low magnification overview image with the area to be analyzed indicated by the black dotted line, and higher magnification image with analyzed area indicated by red dotted line. Scale bars indicate 500 μm (low magnification overview image) and 200 μm (higher magnification image). Credit: Communications Biology (2023). DOI: 10.1038/s42003-023-05347-3

Glucocorticoids regulate a group of brain peptides controlling appetitive behavior, with some increasing appetite (orexigenic) and some decreasing appetite (anorexigenic). Misalignment between light and dark cues led the out-of-phase group's orexigenic hypothalamic neuropeptides (NPY) to become dysregulated, driving an increased desire to eat more during the inactive phase of the day. Rats in the normal dark/light cycle group ate 89% of their daily intake during their active phase, and 12% during their inactive phase. In contrast, the phase-disrupted group consumed 54% of their daily calories during their inactive phase with no corresponding increase in activity during this time period. Hence, when daily glucocorticoid levels are out of synch with light and dark cues, crucial appetite neuropeptides become disordered.

Junk food will make you fat.

Nearly 60% of calories consumed in the United States are junk foods. A recent analysis of two systematic reviews of 281 studies from 36 different countries found an overall prevalence of food addiction. Foods containing high levels of refined carbohydrates or added fats are likely addictive substances.

Ultra-processed foods high in refined carbohydrates and added fats are highly rewarding, appealing, and consumed compulsively and may be addictive. Behaviours around ultra-processed food may meet the criteria for diagnosis of substance use disorder in some people. Ultra-processed food addiction is estimated to occur in 14% of adults and 12% of children and is associated with biopsychological mechanisms of addiction and clinically significant problems. …

This reported prevalence is similar to the levels of addiction seen for other legal substances in adults (eg, 14% for alcohol and 18% for tobacco), but the level of implied addiction in children is unprecedented.

- A DiFeliceantonio, et al.

Refined carbohydrates or fats can release high levels of extracellular dopamine in the brain striatum like the addictive substances nicotine and alcohol.

So, time to go ‘cold turkey’ on the bad stuff before we the hit the ‘turkey time’ holidays. Choose wisely.

https://www.sweetteaandcornbread.net/2013/10/pumpkin-cheesecake-pie.html

versus

https://healthblog.yinteing.com/2013/06/08/is-taking-a-supplement-the-same-as-biting-into-an-apple/

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REFERENCES

And then there were 6 -- kinds of taste, that is. https://www.sciencedaily.com/releases/2023/10/231005110728.htm

Z Liang, et al. The proton channel OTOP1 is a sensor for the taste of ammonium chloride. Nat Commun 14, 6194 (2023). https://doi.org/10.1038/s41467-023-41637-4 https://www.nature.com/articles/s41467-023-41637-4

M Yoshimura, et al. Phase-shifting the circadian glucocorticoid profile induces disordered feeding behaviour by dysregulating hypothalamic neuropeptide gene expression. Communications Biology (2023). DOI:10.1038/s42003-023-05347-3

A DiFeliceantonio, et al. Social, clinical, and policy implications of ultra-processed food addiction, BMJ (2023). DOI: 10.1136/bmj-2023-075354