The functioning of our nervous system harbors extremely complex processes of transmission of nerve impulses and chemicals, neurotransmission being the main phenomenon allowing neurotransmitters to travel along our nervous system, allowing the proper functioning of organs for emotional regulation.
One of the main components involved is this neurotransmission are neural receptors or neuroreceptors. Throughout this article, we will talk about its main characteristics and how it works, as well as the various main classifications and types.
What are Neural Receptors?
Throughout the network that makes it possible to transmit the chemicals of neurotransmission processes, we find neural receptors or neuroreceptors. These little pieces are protein complexes, that is, they are made up of proteins, and they are located in the cell membranes of the neuron.
During neurotransmission, chemicals found in the intercellular space, such as neurotransmitters, meet the cell membrane, along which neural receptors are located. When a neurotransmitter falls on its corresponding receptor, it binds and generates a series of changes inside the cell.
Therefore, a membrane receptor is an essential part of the molecular machinery that enables chemical communication between cells. It should be noted that a neuronal receptor is a specific type of receptor which binds exclusively to a certain number of neurotransmitters and not to another type of molecule.
We can find neuroreceptors in presynaptic and postsynaptic cells. First, we find the so-called autoreceptors, Which are intended to collect the neurotransmitters released by this same cell, providing feedback and intervening on the quantity of neurotransmitters released.
However, when these are found in postsynaptic cells, neural receptors they receive signals that can trigger an electrical potential. This regulates the activity of ion channels. The influx of ions along open ion channels due to chemical neurotransmission can alter the membrane potential of a neuron, resulting in a signal that travels along the axon and is transmitted between neurons and even the whole neural network.
Is it equal to a sensory receptor?
The answer is no. While neural receptors are small agents found in cell membranes and the mission is to transmit information by collecting specific neurotransmittersSensory receptors refer to specialized nerve endings found in sensory organs.
Throughout our body (skin, eyes, tongue, ears, etc.) we find thousands of nerve endings whose main mission is to receive stimuli from the outside and to carry this information to the rest of the nervous system, thus causing all kinds of bodily responses and sensations.
Types of neural receptors according to the form of action
There are two main types of neuroreceptors which can be classified based on how they work. They are ionotropic receptors and metabotropic receptors.
1. Ionotropic receptors
By ionotropic receptors we mean these receptors through which ions can pass. They are thought to be a group of transmembrane channels that open or close in response to the binding of a chemical messenger, that is, a neurotransmitter, to which it is called a “binder.”
The binding site of these ligands in receptors is usually located in a different part of the protein. The direct union between the receptor and the ligand, causes the opening or closing that this characteristic of ion channels; compared to metabotropics who use what are called second messengers.
How ion channels work it will also be different according to the voltageIn other words, they open or close depending on the potential of the membrane. Likewise, there are ion channels that are activated by stretching, that is, they perform one function or another depending on the mechanical deformation of the cell membrane.
2. Metabotropic receptors
Unlike ionotropic receptors which transmit directly, metabotropic receptors they don’t have channels so they use a second messenger which is located inside the cell. In other words, they perform indirect chemical neurotransmission.
these receivers they are usually coupled to G proteins and, while ionic receptors can excite or inhibit a response, metabotropic receptors do not have inhibitory or excitatory functions, but perform a large group of functions.
Among the main functions of metabotropic receptors are to modulate the action of excitatory and inhibitory ion channels, as well as the activation of a cascade of signals that releases calcium stored in cellular reserves.
Types according to neurotransmitter
Besides classifying neurotransmitters based on how they convey information, they can also be classified based on the neurotransmitter they will be attached to.
Here are some of the main classes of neural receptors:
They are activated by the catecholamines adrenaline and norepinephrine.
They play an important role in controlling emotions by being linked to dopamine.
Associated with the neuroeceptor GABA, it is essential in the action of certain drugs such as benzodiazepines, certain epileptics and barbiturates.
They can be divided into ionotropic receptors N-methyl-daspartate (NMDA) and non-NMDA receptors.
They are acetylcholine receptors (ACh) and are subdivided into nicotinics (N1, N2) and muscarinics.
They bind to both endogenous and exogenous opioid neurotransmitters and their activation can result in euphoria on sedation or analgesic effects.
They are serotonin (5-HT) receptors and there are at least 15 subtypes in this classification.