We are talking about neurotransmitters.
Within Neurotransmitters you can define 3
types:
-
Monoamines and other biogenic amines: dopamine (DA), norepinephrine
(noradrenaline; NE, NA), epinephrine
(adrenaline), histamine,
serotonin (SE, 5-HT)
Monoamine neurotransmitters are the
transmitters we are looking for, because they have a big influence on the brain
and moods.
Dopamine has a number of important functions in the
brain; this includes regulation of motor behavior, pleasures related to
motivation and also emotional arousal. It plays a critical role in the reward system; people with
Parkinson's
disease have been linked to low levels of dopamine and people with schizophrenia have been
linked to high levels of dopamine.
Norephinephirne (hormon and neurotransmitter):
It is the hormone and neurotransmitter most responsible for vigilant concentration in contrast to its most chemically similar hormone, dopamine, most responsible for cognitive alertness. One of the most important functions of norepinephrine is its role as the neurotransmitter released from the sympathetic neurons to affect the heart. An increase in norepinephrine from the sympathetic nervous system increases the rate of contractions in the heart.
It is the hormone and neurotransmitter most responsible for vigilant concentration in contrast to its most chemically similar hormone, dopamine, most responsible for cognitive alertness. One of the most important functions of norepinephrine is its role as the neurotransmitter released from the sympathetic neurons to affect the heart. An increase in norepinephrine from the sympathetic nervous system increases the rate of contractions in the heart.
As a stress
hormone, norepinephrine affects parts of the brain, such as the amygdala, where attention and responses
are controlled.Norepinephrine also underlies the fight-or-flight
response, along with epinephrine, directly
increasing heart rate,
triggering the release of glucose
from energy stores, and increasing blood flow to skeletal muscle. It
increases the brain's oxygen supply. Norepinephrine can also suppress neuroinflammation when
released diffusely in the brain from the locus coeruleus.
Epinephrine (neurotransmitter and hormon): produces adrenaline, which is
connected to fear. Epinephrine
(also known as adrenaline, adrenalin, or 4,5-β-trihydroxy-N-methylphenethylamine) is a hormone and a neurotransmitter.Epinephrine
has many functions in the body, regulating heart rate, blood vessel and air
passage diameters, and metabolic shifts; epinephrine release is a crucial
component of the fight-or-flight
response of the sympathetic
nervous system. In chemical terms, epinephrine is one of a group of monoamines called the catecholamines. It is
produced in some neurons
of the central nervous system, and in the chromaffin
cells of the adrenal
medulla from the amino acids
phenylalanine and tyrosine.
Histamine:
Although histamine is small compared to other biological molecules (containing only 17 atoms), it plays an important role in the body. It is known to be involved in 23 different physiological functions. Histamine is known to be involved in so many physiological functions because of its chemical properties that allow it to be so versatile in binding. It is Coulombic (able to carry a charge), conformational, and flexible. This allows it to interact and bind more easily.
Sleep regulation
Histamine is released as a neurotransmitter. The cell
bodies of histaminergics, the
neurons which release histamine, are found in the posterior hypothalamus, in various tuberomammillary
nuclei. From here, these neurons project throughout the brain, to
the cortex through the medial
forebrain bundle. Histaminergic action is known to modulate sleep. Classically, antihistamines
(H1 histamine receptor antagonists) produce sleep. Likewise, destruction of
histamine releasing neurons, or inhibition of histamine synthesis leads to an
inability to maintain vigilance.
Finally, H3 receptor
antagonists increase wakefulness.
It has been shown that histaminergic cells have the
most wakefulness-related firing pattern of any neuronal type thus far recorded.
They fire rapidly during waking, fire more slowly during periods of
relaxation/tiredness and completely stop firing during REM
and NREM (non-REM) sleep.
Histaminergic cells can be recorded firing just before an animal shows signs of
waking.
Suppressive effects
While histamine has stimulatory effects upon neurons,
it also has suppressive ones that protect against the susceptibility to
convulsion, drug sensitization, denervation supersensitivity, ischemic lesions
and stress.[10] It has also been suggested that histamine controls the
mechanisms by which memories and learning are forgotten.
Erection and sexual function
Libido loss and erectile failure can occur during
treatment while using of histamine (H2) receptor antagonists such as cimetidine, ranitidine, and risperidone. The injection
of histamine into the corpus
cavernosum in men with psychogenic impotence produces full or
partial erections in 74% of them. It has been suggested that H2 antagonists may
cause sexual difficulties by reducing the uptake of testosterone.
Schizophrenia
Metabolites of histamine are increased in the
cerebrospinal fluid of people with schizophrenia, while the
efficiency of H(1) receptor binding sites is decreased. Many atypical antipsychotic medications
have the effect of decreasing histamine production (antagonist), because its
use seems to be imbalanced in people with that disorder.
Multiple sclerosis
Histamine therapy for treatment of multiple sclerosis
is currently being studied. The different H receptors have been known to have
different effects on the treatment of this disease. The H1 and H4 receptors, in
one study, have been shown to be counterproductive in the treatment of MS. The
H1 and H4 receptors are thought to increase permeability in the Blood Brain
Barrier, thus increasing infiltration of unwanted cells in the Central Nervous
System. This can cause inflammation, and MS symptom worsening. The H2 and H3
receptors are thought to be helpful when treating MS patients. Histamine has
been shown to help with T-cell differentiation. This is important because in
MS, the body's immune system attacks its own myelin sheaths on nerve cells
(which causes loss of signaling function and eventual nerve degeneration). By
helping T cells to differentiate, the T cells will be less likely to attack the
body's own cells, and instead attack invaders.
Disorders
As an integral part of the immune system, histamine may be involved in immune system
disorders and allergies.
Mastocytosis
is a rare disease in which there is a proliferation of mast cells that produce
excess histamine.
Serotonin: is a monoamine
neurotransmitter. Most is produced by and found in the intestine
(approximately 90%), and the remainder in central
nervous system neurons. It functions to regulate appetite, sleep,
memory and learning, temperature, mood, behaviour, muscle contraction, and
function of the cardiovascular
system and endocrine
system. It is speculated to have a role in depression, as some
depressed patients are seen to have lower concentrations of metabolites of
serotonin in their cerebrospinal
fluid and brain tissue.
Neurotransmitter systems
|
System
|
Origin
|
Effects
|
|
Noradrenaline system
|
•
arousal
•
reward
|
|
|
Dopamine system
|
motor
system, reward, cognition,
|
|
|
Serotonin system
|
caudal dorsal
raphe nucleus
|
Increase (introversion),
mood,
satiety,
body
temperature and sleep,
while decreasing nociception.
|
|
rostral dorsal
raphe nucleus
|
||
|
Cholinergic system
|
pontomesencephalotegmental complex
|
•
learning
•
arousal
•
reward
|
|
medial septal nucleus
|
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