Neurotransmitter

A neurotransmitter is a molecule capable of transmitting information between cells. Most often it is a nerve impulse between neurons, between nerve and muscle cells.

Synthesized neurotransmitter The designation of the neuron synthesizing the neurotransmitter Designation of individual clusters of neurons
Serotonin B B1−B9
Dopamine And A8−A17
Norepinephrine And A1−A7
Adrenaline C C1−C3
Acetylcholine CH CH1−CH6
Histamine E E1−E5

Acetylcholine

It is a mediator that transmits information from preganglionic neurons to postganglionic neurons in the system autonomic nerves. In parasympathetic, acetylcholine is released again at the postganglionic endings. In the sympathetic nervous system, it is released from the postganglionic terminal noradrenaline.

Nicotine receptors

They are part of ion channel. Individual channels differ from each other in structure. The Muscle type has two subunits α1 and one subunit β, γ, δ (found in embryonic muscle), but in adulthood the γ is replaced by a subunit ε. The neuronal type has a α subunit and a β subunit, there may also be a situation where both subunits have α.

  • Neuronal type;
  • muscle type;
  • ganglion type.

Muscarinic receptors

They are in the effector organs. M1, M2, M3, M4, M5

Function

  • Cognitive processes − memory and learning (decreased amount of ACh = Alzheimer's).
  • Importance in regulating wakefulness and sleep.
  • Motor skills.
  • Motivation, in the reward process.
  • In PNS – skeletal muscle activity, modulation of transmission nociception.
  • In the ANS – ganglia and parasympathetic.

Catecholamines

Tyrosine → DOPA → Dopamine → NA (norepinephrine) → A (epinephrine)

Dopamine

Scheme of action of dopamine
Dopaminergic D2 receptor decline

Dopamine is synthesized in nuclei A8−A17. The site of action is sympathetic ganglia.

Major dopaminergic neurons

A8, A9, A10= midbrain
A9= Substantia nigra
A11−A15= Midbrain
A12= Nucleus arcuatus
A17= retina

Receptors

D 1-like family − D1,D 5

increase effects of adenylate cyclase (↑ cAMP)

D 2-like family − D2, D3, D4

reduce the effects of adenylate cyclase (↓ cAMP)

Functions

They are of great importance in motivational behavior and addiction. In the case of an unexpected reward, the stimulation' of DA is pronounced, which disappears during repetition and learning if the presentation of the reward does not evoke the stimulation of DA. In the absence of the expected reward, the DA signal is reduced. Two phases of the stimulus:

stimulus phase − expectation of the pleasant
phase of consumption − experiencing a pleasurable stimulus

It is also applied in the consolidation of memory traces. It is important in the regulation of hypothalamic-pituitary system' and in the regulation of motor functions, but also in the transmission and processing of nociceptive signals.

Faults

Typically, Parkinson's disease and schizophrenia. There are also depression, substance addiction and eating disorders.

Adrenaline, Noradrenaline

Receptors

The receptors are 'adrenergic, with affinity for A and NA being almost the same.

  • α1
  • α1A
  • α1B
  • α1D
  • α2
  • α2A
  • α2B
  • α2C
  • α2D
  • β1
  • β2
  • β3

Functions

They are used in the stress response'. This is the so-called eustress, when an individual gives a double performance and the level is within the homeostatic limits. They are also important for attention, wakefulness and sleep.

Synapse

Serotonin

As a neurotransmitter, it acts vasoconstrictive. It affects sleep and thermoregulation. Also called the hormone of happiness.

Receptors

The receptors for serotonin are predominantly metabotropic, coupled to G protein. It can bind to a large number of receptor types. The information is also led to all areas of the CNS.

Functions

They are used in waking and sleeping, circadian rhythms. It is also related to pain, food intake and sexual behavior. Serotonin deficiency is associated with depression, anxieta and migraine.

Histamine

The nuclei are designated E1−E5. They project into the spinal nuclei and into the cerebellum. Efferent pathways are to the entire cerebral cortex.

Functions

Application in the regulation of sleep cycles, energy and endocrine homeostasis. In the regulation of body temperature and food intake. It is related to the regulation of secretion hypothalamic-pituitary system. Also synaptic plasticity, learning and nociceptive signals.

GABA receptor

Excitatory amino acids

Glutamate

It interferes with and is found everywhere in the CNS. Its receptors are metabotropic, where the first, second and third groups of glutamate receptors and ionotropic receptors are located, which include AMPA, kainate, NMDA. The function is applied in motor coordination, memory processes (long-term potentiation), emotional processes and sensory information transfers. Decreased levels are associated with epilepsy, Huntington's chorea, ischaemic brain injury.

Inhibitory amino acids

GABA

The receptors for GABA are ionotropic GABA A and metabotropic GABA B. Its important pathways lead to the cerebellum. The function is associated with monosynaptic and polysynaptic signal transmissions. Transmission of nociceptive information, presynaptic selection of afferent flow of information into the CNS. They cause the chloride channel to open, resulting in hyperpolarization. Decreased GABA levels are associated with Huntington's chorea, is related to epilepsy and anxiety, i.e. anxiety.

References

  • AMBLER, Zdeněk. Basics of neurology. 6th edition. Prague: Galén, 2006. pp. 171-181. ISBN 80-7262-433-4 .

Source

  • Lecture in physiology, second year.
  • AMBLER, Zdeněk. Basics of neurology. 6th edition. Prague: Galén, 2006. pp. 171-181. ISBN 80-7262-433-4 .
  • AMBLER, Zdeněk. Basics of neurology. 6th edition. Prague: Galén, 2006. pp. 171-181. ISBN 80-7262-433-4 .