Neuronal receptors: what they are, types and function

These protein assemblies allow neurons in our nervous system to communicate.

The functioning of our nervous system involves highly complex processes of transmission of nerve impulses and chemical substances. Neurotransmission is the main phenomenon that allows neurotransmitters to travel throughout our nervous system, enabling everything from the correct functioning of organs to emotional regulation.

Some of the main components involved in this neurotransmission are neuronal receptors or neuroreceptors.. Throughout this article we will talk about their main characteristics and functioning, as well as the different classifications and main types.

What are neuronal receptors?

Within the whole framework that makes possible the transmission of the chemical substances involved in neurotransmission processes, we find the neuronal receptors or neuroreceptors. These small elements are protein complexes, i.e., they are formed by proteins, and are located in the cell membranes of the are located in the cell membranes of the neuron..

During neurotransmission, chemicals in the intercellular space, such as neurotransmitters, encounter the cell membrane, along which the neuronal receptors are located. When a neurotransmitter encounters its corresponding receptor, they will bind and generate a series of changes inside the cell.

Thus, a membrane receptor is an essential piece of the molecular an essential piece of the molecular machinery that enables chemical communication between cells. between cells. It is necessary to specify that a neuronal receptor is a specific type of receptor that only binds exclusively with a series of neurotransmitters and not with other types of molecules.

Neuroreceptors can be found both in presynaptic cells and in postsynaptic cells. In the former, we find the so-called autoreceptorswhich are destined to reuptake the neurotransmitters released by that same cell, providing feedback and mediating the amount of neurotransmitters released.

However, when these are found in postsynaptic cells, the neuronal receptors receive signals that can trigger an electric potential 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 change the membrane potential of a neuron, resulting in a signal that travels along the axon and is transmitted between neurons and even to the entire neuronal network.

Is it the same as a sensory receptor?

The answer is no. While neuronal receptors are small agents found in the membranes of cells and whose mission is to transmit information through the reuptake of 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 transport this information to the rest of the nervous system, thus provoking all kinds of bodily responses and sensations.

Types of neuronal receptors according to mode of action.

There are two main types of neuroreceptors which can be classified according to how they function. These are ionotropic receptors and metabotropic receptors.

1. Ionotropic receptors

Ionotropic receptors are those receptors through which ionotropic receptors through which ions can pass.. They are considered as a group of transmembrane channels that open or close in response to the binding of a chemical messenger, i.e. a neurotransmitter, which is called a "ligand".

The binding site of these ligands in the receptors is usually located in a different portion of the protein. The direct binding between the receptor and the ligand causes the opening or closing that is characteristic of ion channels, as opposed to metabotropic channels that use so-called second messengers.

The functioning of ion channels will also be different depending on the voltagethat is, they open or close depending on the membrane potential. In the same way, there are ion channels that activate by stretching, which means that they perform one function or another depending on the mechanical deformation of the cell membrane.

Metabotropic receptors

In contrast to the ionotropic receptors that perform transmission directly, metabotropic receptors have no channels, so they use a second messenger located inside the cell. which is located inside the cell. That is, they perform an indirect chemical neurotransmission.

These receptors are usually coupled to G proteins proteins, and while ion receptors can either excite or inhibit a response, metabotropic receptors have neither inhibitory nor excitatory functions, but exert a Wide range of functions.

Among the main functions of metabotropic receptors are those of modulating the action of excitatory and inhibitory ion channels, as well as activating a signaling cascade that releases calcium stored in the cell's stored in the cell's reserves.

Types according to neurotransmitter

In addition to the classification of neurotransmitters according to the way in which they carry out the transmission of information, they can also be classified according to the neurotransmitter to which they are coupled.

These are some of the main classes of neuronal receptors:

1. adrenergic

They are activated by the catecholamines adrenaline and noradrenaline.

2. Dopaminergic

They play an important role in the control of emotions because they are linked to dopamine.

3. GABAergic

Associated to the neuroreceptor GABA, it is essential in the action of some drugs such as benzodiazepines, some epileptics and barbiturates.

4. Glutamatergic

They can be divided into ionotropic N-methyl-daspartate (NMDA) receptors and non-NMDA receptors.

5. Cholinergic

They are acetylcholine (ACh) receptors and are subdivided into nicotinic (N1,N2) and muscarinic.

6. Opioid

They bind to both endogenous and exogenous opioid neurotransmitters and their activation can cause from euphoric sensations to sedation or analgesic effects.

7. Serotonergic

They are serotonin (5-HT) receptors and there are at least 15 subtypes within this classification.