What are the types of neurotransmitters?

When studying biology in high school, you will want to learn about nerve conduction. At this time, you will understand the term neurotransmitter, also known as neurotransmitter. This is a very important subject in biology. It is a very complex series of conduction processes in the human body. It plays a very important role in maintaining human physical activities. In biology, neurotransmitters are mainly classified into the following categories.

Types of neurotransmitters:

Neurotransmitters in the brain are divided into four categories, namely biogenic amines, amino acids, peptides, and others. Biogenic amine neurotransmitters were the first to be discovered, including dopamine (DA), norepinephrine (NE), epinephrine (E), and 5-hydroxytryptamine (5-HT), also known as serotonin. Amino acid neurotransmitters include: gamma-aminobutyric acid (GABA), glycine, glutamate, histamine, and acetylcholine (Ach). Peptide neurotransmitters are divided into: endogenous opioid peptides, substance P, vasopressin, cholecystokinin (CCK), somatostatin, vasopressin and oxytocin, and neuropeptide y.

Other neurotransmitters are divided into: nucleotides, eicosanoids, anandamide, and sigma receptors (σ receptors). Other categories: Nitric oxide is generally considered to be a neurotransmitter. It is not released by exocytosis, but instead passes through the cell membrane due to its lipid solubility, exerts its effects and is inactivated through chemical reactions. It plays the role of retrograde messenger in synaptic plasticity changes and long-term potentiation effects. Important neurotransmitters and neuromodulators are:

①Acetylcholine. The earliest neurotransmitter identified. The neuromuscular junctions of skeletal muscles of vertebrates and the motor muscle junctions of some lower animals such as mollusks, annelids and flatworms all use acetylcholine as an excitatory transmitter. The transmitter between the parasympathetic nerves and effectors of vertebrates is also acetylcholine, but some are excitatory (such as in the digestive tract) and some are inhibitory (such as in the myocardium). The method developed by Chinese physiologists Zhang Xijun and JH Gardham (1932) for quantitative determination of acetylcholine in frog rectus abdominis muscle specimens played an important role in the study of acetylcholine and still has application value today.

②Catecholamines. Includes norepinephrine (NE), epinephrine (E) and dopamine (DA). The junction between sympathetic ganglion cells and effectors is norepinephrine as the neurotransmitter.

③5-hydroxytryptamine (5-HT).

Serotonin neurons are mainly concentrated in the raphe nuclei of the pons. They are generally inhibitory, but there are also excitatory ones. Research by some Chinese scholars has shown that serotonin plays an important role in acupuncture analgesia. ④Amino acid transmitters. The neurotransmitters identified are glutamate (Glu), γ-aminobutyric acid (GABA), and glycine (Gly). Glutamate is the neurotransmitter at the neuromuscular junction of crustaceans. GABA was first discovered as a neurotransmitter at the junction between the chelicerae muscles and inhibitory nerve fibers of crayfish. It was later demonstrated that GABA is also an inhibitory neurotransmitter of the central nervous system. Synapses using glycine as a neurotransmitter are mainly distributed in the spinal cord and are also inhibitory neurotransmitters.

⑤ Polypeptide neuroactive substances.

It has been found that many smaller peptides have neuroactive properties, and neurons contain some small peptides, although it is not yet certain that they are neurotransmitters. For example, insulin, glucagon and cholecystokinin, which are present in the digestive tract, have been shown to be also contained in central neurons.