Coffee in the genes
Eight reasons to love coffee
This time it's about drinking coffee. The authors of the work examined the genomes of 120,000 coffee lovers and found several SNPs (consequences of point mutations) associated with the love of coffee.
The main substance contained in coffee and affecting the body is the alkaloid caffeine. Caffeine has a diverse effect on the human body. First, caffeine blocks cAMP phosphodiesterase. Cyclic adenosine monophosphate (cAMP) is a signaling molecule that primarily directs the secretion of adrenaline. Phosphodiesterase must destroy the cAMP that has done its job, and when it is blocked, cAMP accumulates in the body and causes an increase in adrenaline levels.
The mechanism of action of caffeine in the brain is based on the fact that caffeine is structurally similar to the nucleoside neurotransmitter adenosine. There are adenosine receptors in the brain, when these receptors interact with their ligand adenosine, the inhibition process is triggered. Due to the incomplete similarity, caffeine can bind to the receptor, but it cannot transmit a signal of inhibition further to the brain cells. Because of this, caffeine has a stimulating effect. People who drink a lot of coffee may have a compensatory effect: additional adenosine receptors appear in the brain. This leads to the fact that when it is not possible to drink coffee, such people have drowsiness, fatigue and depression for no apparent reason.
Thanks to these two mechanisms, after consuming caffeine, blood pressure increases (especially important for hypotensive people in the morning), heart rate increases, cognitive abilities improve, and sometimes mood. After a few hours, these positive effects pass for someone and are replaced by fatigue and a decrease in working capacity. This is usually regarded by avid amateurs as a signal to drink more coffee.
Less pleasant effects are that the accumulation of cAMP in the cells of the gastric epithelium causes increased acid secretion, as well as increased diuresis.
Whether a person develops an addiction to coffee depends, apparently, on how pronounced certain consequences of drinking coffee are, and this may be genetically determined. For example, there are many coffee lovers among hypotonics, and there is no point in drinking coffee if pleasant effects are replaced by unpleasant ones too quickly. But if the stimulating effect, on the contrary, is slow, then there will be no desire to drink the next cup.
A similar story with alcohol. Two enzymes are responsible for the metabolism of alcohol in humans: the first – alcohol dehydrogenase converts ethyl alcohol into aldehyde, and the second – aldehyde dehydrogenase aldehyde into carboxylic acid, which is excreted from the body. We owe almost all the pleasant effects of intoxication to alcohol, and the unpleasant ones to aldehyde. Both enzymes have genetically determined variants associated with faster or slower enzyme activity. And if a person's alcohol slowly turns into an aldehyde, and the aldehyde quickly turns further, then a person feels good for a long time, but not for long, and the risk of alcohol abuse increases. But when it's easy and fun – half an hour, and it's bad all night and all morning – there is almost no chance to sleep.
SNP is a single nucleotide polymorphism. They arise due to point mutations. Changes in one nucleotide can have a variety of consequences: sometimes such a substitution in the protein coding sequence makes the gene completely non-functional, but often only slightly affects its activity or ability to bind to other proteins. Often substitutions do not occur in protein coding, but in regulatory areas – then the substitution has even less effect on the phenotype, but it may have some effect. Such polymorphisms are being studied quite actively, because it is in them that a significant part of the difference between people lies, and there is hope, by studying them, to find out the causes of some diseases and features and learn how to correct them.
Previously, two polymorphisms associated with the constant use of coffee were known. These are mutations in the regulatory region of the cytochrome P450 gene and the protein directly regulating the synthesis of cytochrome 450 (aryl hydrocarbon receptor). Cytochrome P450 metabolizes (oxidizes) many exogenous and endogenous substances, including caffeine.
A new study has found eight more mutations associated with the love of coffee.
Among these mutations, just one more was found in the regulatory region of cytochrome P450, and one more in the AHR receptor. The variant associated with more coffee consumption is associated with faster caffeine metabolism and lower caffeine content in blood plasma. Apparently, people with a slow caffeine metabolism are less likely to have a desire to drink it again.
Two more mutations were found in genes and regulatory regions of genes associated with the metabolism of xenobiotics, which were not previously associated with increased coffee consumption. These are the POR and ABCG2 genes. The first gene encodes another enzyme involved directly in metabolism, the second one is responsible for the transport of xenobiotics, which is caffeine.
Two more mutations affect the nervous system. One of them is in the gene encoding neurotrophic brain factor (BDNF) This protein stimulates the growth and development of neurons, regulates the synthesis of mood-related neurotransmitters. Perhaps because of a mutation in this protein, the positive effect of caffeine on mood and performance is especially strong. Another mutation is in the regulatory region of the SLC6A4 gene encoding the neurotransmitter serotonin transporter. Serotonin is actively involved in the formation of emotions and behavior, especially eating behavior.
About two more genes – GCKR and MLXIPL, in which mutations associated with increased coffee consumption were found. But how exactly they are related to coffee is still unclear.
This work once again demonstrates that many behavioral features have a genetic component. This does not mean, of course, that genes do not leave a person with a choice. There is always a choice, but when analyzing a large number of people, it becomes clear that people with a certain genotype are more likely to get into the habit of drinking coffee.
Portal "Eternal youth" http://vechnayamolodost.ru09.10.2014