Molecular Neuroscience Ion Channels and its Receptors

Description

A branch of neuroscience known as molecular neuroscience studies the principles from molecular biology are used to study human nervous systems. The scope of this subject involves topics like molecular neuroanatomy, neural signalling mechanisms, genetic and epigenetic influences on neuronal development, and the molecular origins of neuroplasticity and neurodegenerative disorders. Similar to molecular biology, molecular neuroscience is a new and rapidly evolving subject.

In molecular biology, synapses-gaps between the channels that help for chemical transmission are the primary means of communication between neurons. Neurotransmitters, the chemicals that are transmitted throughout the body, control a significant portion of essential body systems. Neurotransmitters can be located anatomically using labelling techniques. By using formaldehyde to fix sections of neural tissue, it is feasible to chemically identify certain neurotransmitters, such as catecholamines.

Voltage-gated ion channels

Voltage-gated ion channels are present in excited cells of living organisms. These can be seen in neurons all over the neurological system. There are three different ion channels, they are as follows:

• Sodium ion channels

• Potassium ion channels

• Calcium ion channels

Receptors

Ionotropic and metabotropic receptors are two examples of many types of receptors that can be used for cell signalling and communication. Ionotropic receptors are linked to fast signal transmission, whereas metabotropic receptors are linked to slow signal transmission. These cell surface receptor types are distinguished by the mechanism and duration of action. A large range of cell-surface receptors with significantly diverse signalling cascades are covered by metabolotropic receptors.

Ionotropic receptors

Ionotropic receptors, sometimes known to as ligand-gated ion channels, are fast-acting receptors that control ion channel flow with ligand-binding to mediate neurological and physiological function. The flow of ligand-gated ion channels regulates a number of cell surface receptors, including the glutamate, GABA, and nicotinic receptors. The primary inhibitory and excitatory neurotransmitters in the brain are GABA and glutamate, respectively.

GABA receptors

The GABAB receptor is metabotropic, whereas the GABAA and GABAC receptors are known to be ionotropic. GABAA receptors, which are present on neurons, glial cells, and adrenal medulla cells, mediate rapid inhibitory responses in the Central Nervous System (CNS). It is in charge of causing Cl- ion influx into cells, which lowers the likelihood that membrane depolarization will happen when a graded potential or an action potential occurs. Non-endogenous ligands can also interact with GABA receptors to affect activity. For instance, the substance diazepam is an allosteric activator that enhances the receptor's affinity for GABA. Diazepam is a helpful tranquillizer or anticonvulsant due to the increased physiological inhibitory effects generated on by increased GABA binding (antiepileptic drugs). On the other hand, convulsants like picrotoxin have the ability to target GABA receptors by reducing Chloride cellular inflow. This substance's antagonistic mechanism of action does not directly target the GABA receptor, but other substances, such as T-butylbicyclophorothionate (TBPS) and pentylenetetrazole, are capable of allosteric inactivation (PZT). In comparison to GABAA receptors, GABAC receptors have a higher affinity for GABA, are more likely to remain active for a longer period of time, and are more likely to respond to lower GABA concentrations.

Glutamate receptors

NMDA, AMPA, and kainate receptors are examples of ionotropic glutamate receptors. These receptors were given their names in recognition of agonists that promote glutamate action. The excitatory mechanisms that NMDA receptors use to influence neuronal plasticity in learning and memory as well as neuropathologies including stroke and epilepsy are significant. Similar to ionotropic GABA receptors, NDMA receptors have many binding sites and can be affected by co-agonists like the glycine neurotransmitter or phencyclidine (PCP). Depending on voltage and membrane potential, exogenous Mg²⁺ ions can inhibit the Ca²⁺ current that the NMDA receptors carry. Excitatory postsynaptic potentials (EPSPs) generated by NMDA receptors boost this Ca²⁺ influx by triggering Ca²⁺ -based signalling cascades (such as neurotransmitter release). Compared to other ionotropic glutamate receptors, AMPA produce excitatory postsynaptic currents that are longer and larger.

Nicotinic ACh receptors

Acetylcholine (ACh) neurotransmitter is activated by nicotinic receptors to cause non-selective cation channel flow, which results in excitatory postsynaptic reactions. Receptor activity, which nicotine use can influence, results in high degrees of exhilaration, relaxation, and inevitably addiction.

Metabotropic receptors

Postsynaptic cells contain slow-response receptors called metabolotropic receptors. Usually, more complex intracellular biochemical changes characterise these sluggish responses. Metabotropic receptor responses to neurotransmitter uptake can activate intracellular enzymes and cascades involving second messengers.

G protein-linked receptors

The signal of a particular neurotransmitter can be significantly amplified by the G protein-linked signalling cascade, resulting in the production of hundreds to thousands of second messengers in a cell.