Chemistry of the Brain: Neurotransmitters

           Our brain performs numerous functions throughout the day which lends itself the question, ‘how are these functions carried out?’ What processes or chemicals facilitate these functions. The biochemicals responsible for this are called neurotransmitters. The process for information to be transferred begins at the neurons in our brain. Chemicals, called neurotransmitters, are passed between neurons through gaps called synapses. Essentially, the neurotransmitter is passed from one neuron to the next where it may be accepted at the neuron receptor. At the receptor the action potential of the neurotransmitter is either likely to happen or unlikely. Some of these neurotransmitters are epinephrine, serotonin, and histamine.


Epinephrine is a neurotransmitter that is very prevalent in our lives. More commonly known as adrenaline, epinephrine is responsible for the ‘Fight or Flight’ response in our brain. With a C9H13NO3 molecular formula and a 183.20 molar mass, epinephrine is actually secreted by the medulla in the adrenal gland in the kidney. For this reason, epinephrine is considered both as a hormone and a neurotransmitter by many chemists. Although its secretion site is different from the other neurotransmitters, epinephrine’s creation in the medulla makes sense because the medulla is responsible for maintaining homeostasis in the blood between blood, salt and water. It seems logical for a chemical revolving around ‘Flight or Fight’ because during times of high pressure and stress, epinephrine is secreted which then stimulates the heart thereby changing the blood pressure. The increased

blood pressure increases the rate of the heartbeat, thereby increasing the flow of O2 into the bloodstream and to the tissues. The respiratory passages becomes dilated, thereby increasing the input of O2. The increased heartbeat and blood pressure increases reaction time in the animal thereby keeping it more alert during the time of stress. In addition, epinephrine also gets sent to the muscles and lungs for a quick burst of energy.


           Serotonin is a neurotransmitter, but you’d be surprised where it is: ninety percent of it is not anywhere in your nervous system. Eighty percent of it is in your stomach, regulating intestinal movements. Another ten percent is in your blood platelets, where it regulates hemostasis and clots the blood. The last ten percent is in your central nervous system. Serotonin has a molecular formula of C10H12N2O and a molecular weight of 176.25 g/mol. But what is this relatively simple molecule (in comparison to monsters such as hemoglobin) doing in your intestines? Serotonin is proven to have control over smooth muscle, which controls involuntary

movement of muscles;  it just so happens that your intestine is made up of smooth muscle. But serotonin is also a regulator, which is why it is located in the nervous system. The two brain structures where it resides are the hypothalamus, which deals with regulation of homeostasis in general, and the basal ganglia, dealing with movement and thinking.

            If you’re suffering from sleep deprivation, a good portion of the problems you experience are blamed on serotonin. Studies have shown that a limited amount of serotonin has led to depression, insomnia and a strong desire to consume food. Ever wake up in the middle of the night and get a midnight snack? Serotonin regulates insulin and IGF, critical in the maintenance of blood sugar levels. In addition to controlling food, serotonin (along with melatonin) is involved in regulating our sleep and wake cycle (also called a circadian rhythm): high levels of serotonin are associated with wakefulness and lower levels with sleep. Thus, when you’re sleepy, you might also get hungry. Also, since serotonin controls and regulates our thoughts so that they flow in a orderly manner, as one sleeps their serotonin levels decrease and our thoughts become able to run wild to the point where our brain is able to create its own images, also known as dreams, during REM sleep. In a medicinal sense, anti-depressants often work as selective serotonin reuptake inhibitors (SSRIs), where they block a neuron from taking back the serotonin for later use, allowing the desired emotion to continue being perceived (in this case, usually pleasant experiences).


         Compared to other neurotransmitters, histamine is a relatively small compound; its molecular weight: 111.15 g/mol. Histamine is an amine, being based off of a nitrogenous compound. Most everyday discussion and recognition of histamine revolves around its function in the immunological response to allergens. This is what creates the classic systems of an allergic response; the runny nose, watery eyes, and endless sneezing that characterize this event. Many of you who happen upon this may sympathize and roll your eyes when the calendar hits April.

           Besides its well known role in the allergic response cycle, it is responsible for the physiological regulation of the gut and is important as a neurotransmitter. It causes capillaries to increase in their permeability to white blood cells in order to counteract invaders, and is found in essentially all animal cells. Histamine is formed by the removal of a carboxyl group from a molecule of the amino acid histidine. This reaction occurs in things called mast cells, although it has also been found produced in the white blood cells in lungs that produce pus. Besides that, histamine can be found in the brain and acts a neurotransmitter.

           It was only recently, within the past two or three decades, that histamine’s role as an important neurotransmitter was discovered. In this form and function, it originates from the posterior hypothalamus and is relevant in most of the brain beyond that. As a neurotransmitter, it is most closely linked with arousal, pituitary secretions, and waking, as well as suppression of eating. It has been found that low levels of this molecule correspond with convulsions and seizures, and also sufferers of Alzheimer’s disease. Conversely, high levels of histamine are recorded in patients with Parkinson’s disease and those with schizophrenia. Histamine also seems to be involved in recovery from brain injuries involving the neurons. It is also known to be vital to maintaining the sleep-wake cycle. particularly in maintaining wakefulness. This information is particularly valuable to constantly sleepy students.


          And so, neurotransmitters are what get information from your brain out towards wherever it needs to go. Here, three of those neurotransmitters are covered. Epinephrine runs rampant when your family decides to pull a practical prank on you. Serotonin is heavily dependent on sleep; it helps you maintain some of your sanity. Histamine makes sure you don’t die when you eat that lobster. As time goes on, each one of these will take you on an adventure, leading to the end goal of making you aware of what’s going on in your body (not anatomically, chemically) and as to why you should probably get some sleep. So until next time, try and get some sleep, your body (and its neurotransmitters) will thank you for it.


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