The receptors for neurotransmitters are located at

Neurotransmitter is a substance located in neurons and is also a substance that is of great significance to the human body's sensory nerves. Neurotransmitter receptors also have a certain influence on neurotransmitters. This substance is generally located outside the cell, across the membrane or in the cytoplasm. The neurotransmitter receptors in different locations have different functions. The neurotransmitter receptors will be introduced in detail below!

1. What are neurotransmitter receptors?

Receptors coupled to second messengers are usually monomeric structures with three components: the extracellular part, which is the site of glycosylation; the transmembrane part, which is bag-shaped and generally believed to be the site where neurotransmitters act; and the intracytoplasmic part, which is where G proteins bind or phosphorylate to regulate the receptors. Ion channel receptors are all complex structures. In certain instances, activation of the receptor causes a change in ion channel permeability. In other cases, activation of second messengers causes changes in channel conductance.

2. Life Cycle

In the central nervous system (CNS), the most important mode of synaptic transmission is neurochemical transmission. After being released from the presynaptic membrane, neurotransmitters immediately bind to the corresponding postsynaptic membrane receptors, generating a synaptic depolarization potential or hyperpolarization potential, resulting in an increase or decrease in the excitability of the postsynaptic nerve. The action of neurotransmitters can be terminated through two pathways: one is recycling inhibition, that is, the excess neurotransmitters in the synaptic cleft are recycled to the presynaptic neuron through the action of presynaptic carriers and stored in vesicles; the other pathway is enzymatic hydrolysis. Taking dopamine (DA) as an example, it is metabolized and inactivated through the action of monoamine oxidase (MAO) located in the mitochondria and catecholamine o-methyltransferase (COMT) located in the cytoplasm.

3. Standards

Neurotransmitters must meet the following criteria: ① Synthesized within neurons. ②. Amount stored in synaptic neurons and released at a certain concentration (with significant physiological effects) when polarized. ③. When used as a drug, the exogenous molecule resembles endogenous neurotransmitters. ④. The mechanism of neurons or synaptic clefts is the clearance or inactivation of neurotransmitters. If all criteria are not met, it is called a "proposed neurotransmitter".