Neurotransmitters are signaling molecules, secreted by neurons to communicate with another cell across a synapse. This other cell can be another neuron, a gland, or a muscle cell. They are important in controlling movement, sensation, and memory. Learn more about neurotransmitters and their effects on the human body.
Excitatory neurotransmitters
Excitatory neurotransmitters are chemicals in the body that are responsible for the actions of neurons. They are most abundant in the brain and play a key role in cognition. However, excessive amounts of these chemicals can cause damage to the brain, leading to diseases like Alzheimer’s and Parkinson’s disease.
These chemicals release from the axon terminals of neurons in response to electrical signals. The signal causes vesicles of neurotransmitters to fuse with the membrane of the nerve cell. From here, they travel across the synapse to the neighboring neuron. Once released, these neurotransmitters bind with the receptors located on the neighboring neuron’s dendrites. In this way, neurotransmitters can either stimulate or inhibit the receiving neuron.
Neurotransmitters can act like a lock-and-key system, only binding to specific receptors on neurons. This triggers changes in the receiving cell. They can also block the signal or prevent it from proceeding. This means that high levels of excitatory neurotransmitters can cause muscle contractions or memory loss. Scientists are able to study these chemicals by observing the vesicles that contain neurotransmitters.
Excitatory neurotransmitters travel to the dendritic spine of a postsynaptic neuron. They bind to a transmembrane receptor protein. The binding of the neurotransmitter activates ion channels that allow certain ions to move along electrochemical gradients. Eventually, the neurotransmitter causes an action potential to form.
Excitatory neurotransmitters are responsible for stimulating the brain while inhibitory neurotransmitters suppress it. The excitatory neurotransmitters, like epinephrine, stimulate the firing of the action potential of a neuron. In contrast, inhibitory neurotransmitters inhibit the firing of commands. These two types of neurotransmitters are essential to the proper functioning of the body.
Endorphins are, naturally produced by the body in response to pain. They also trigger the body to feel good and are responsible for the sensation of euphoria. Norepinephrine is another neurotransmitter that plays a key role in alertness and mobilization. It helps the body fight off threats and respond to stressful situations.
Similarly, excitatory neurotransmitters stimulate muscles and nerve cells. They carry messages from neuronal cells to their target cells, whether another neuron, muscle cells, or glands. The nervous system contains billions of neurotransmitter molecules that constantly communicate with each other. They regulate everything in the body and play an important role in maintaining the body’s health.
Purines
Purines are neurotransmitters that affect the behavior of nerve cells. They are fundamental elements of bioenergetics. Researchers first suggested the role of purines in the nervous system around 90 years ago when they found that adenine interfered with cardiac rhythms, indicating an extracellular signalling function. Later, researchers Wilhelm Feldberg and Catherine Hebb reported that adenine stimulated the release of ATP in rabbits and cats. These findings led to the recognition of purines as neurotransmitters.
Purines play an important role in neuronal differentiation. Defective purine metabolism implicates in several inherited disorders. For example, a disorder of hypoxanthine guanine phosphoribosyltransferase (HGPT) is responsible for the neurological disorder Lesch-Nyhan disease. However, current understanding of purine metabolism remains incomplete.
The regulation of purine levels in the nervous system is complex and poorly understood. Purines are important for several aspects of neuronal differentiation and function, and many neurological diseases associate with their deficiency. Further studies are needed to unravel the complex behavioral and neurological syndromes associated with purine deficiencies.
The production of purines in the body is largely dependent on the amount of energy consumed. They act as a substrate for various biochemical processes, including energy production and energy storage. The main ligands for purinergic receptors are adenosine, ATP, and UTP. They also function as a component of nucleosides, which are composed of a purine or pyrimidine base linked to a sugar called pentose. These compounds are also called ribonucleosides.
The synthesis of purines in the body mainly carries out in the liver. Purine rings are, synthesized by compiling atoms from different sources, such as ribose-5-phosphate and nucleotides. The synthesis process takes about 10 steps. In eukaryotes, the enzymes involved in the purine synthesis process form a multienzyme complex.
The purine metabolites present in serum are, measured to determine the purine concentrations in different compartments of the body. In healthy individuals, the concentration of purines in serum is well below the detection limit. However, the amount of purines in serum may vary among individuals. The purine concentrations in blood and other tissues should determine by using the appropriate methods.
The final product of purine metabolism in humans and primates is urate. In most animals, urate degrades to allantoin by an enzyme called uricase. If the body cannot recycle the purine, the urate excretes in the urine. This excretion of purine-containing substances may have implications for cancer development.
The concentration of purines in adenine nucleotides varies between different cell lines. Adenine nucleotide is higher in high-density cell cultures, but lower concentrations are observed in lower-density cultures. Both AMP and IMP are, detected at low concentrations.
Gasotransmitters
The term “gasotransmitters” refers to various gaseous molecules that are, synthesized in the body. Some examples of these molecules include nitric oxide, hydrogen sulfide, carbon monoxide, and nitrous oxide. These molecules can transmit information to or from cells.
These molecules are small, and their main functions include signal transduction and modulation of the metabolic system. They have a short half-life, low molecular weight, and are highly soluble, which allows them to pass through cell membranes easily. Gasotransmitters are endogenously produced and their biological functions are well-defined at physiological concentrations. These molecules are also capable of being mimicked by exogenous counterparts. Furthermore, gasotransmitters can have both endocrine and paracrine effects.
Gasotransmitters play an important role in regulating neuronal activity, often grouped as signaling molecules. Some of these molecules link to the development of anxiety. However, the neuromolecular mechanism of these molecules is still poorly understood. This is why further research urgently needs to identify the role of these gasotransmitters in anxiety.
Another important gasotransmitter is hydrogen sulfide. It has a characteristic smell of rotten eggs and belongs to the family of gaseous neurotransmitters. It has many functions, including regulating calcium homeostasis and preventing oxidative stress.
