Neurotransmitters 1

where do NT come from?

from inside the body (endogenous)

where are NT found in neurons

they are found in at the axon terminals of the presynaptic neuron

what are NT made of

they are made of enzymes (that are specific to the type of NT)

where and when are NTs released?

when an action potential reaches the axon terminals, the NTs are released (at axon terminals)

Define Neurotransmitter (NT)

(endo, found, made, released)

a substance with a internal origin (endogenous)

• found in presynaptic neuron (axon terminals)

• made from (specific) enzymes of the presynaptic cell

• released when action potential reaches axon terminals (not at other times)

NT: Post synaptic membrane criteria

• Post synaptic membrane has receptors specific to the NT

• the PS membrane behaves to NT the same way when artificially applied as it does naturally

• also blocking the NT stops the activity of the presynaptic cell affecting the post synaptic cell (helps differentiate from another molecule)

name the NT families (Aang)

• Amino acids

• Amines

• Neuropeptides

• Gases

Amino acid family (GGGH)

(origin, types?)

single amino acids molecules in the cell come from diet no synthesis required

Gamma aminobutyric acid (GABA)

Glutamate

Glycine

Histamine

Amines family (ACI)

(origin, types?)

modfied amino acid (ex. molecule added)

• Acetylcholine

• Catecholamines

• Indoleamines

Catecholamines

family? subtypes? (NED)

norepinephrine (NE)

epinephrine

dopamine (DA)

Indoleamines

family? subtypes? (SM)

Serotonin

Melatonin

Neuropeptide family

structure? subtypes: (OO)?

large molecules: chains of amino acids (2-50)

Opioid peptides

Other neuropeptides

Opioid peptides (EatingED)

(family?, subtypes?)

of the neuropeptide family

Enkephalins

Endorphines

Dynrophins

Other neuropeptides

family? types?:

(Oxes, Save, Chole and Vanessas, Necks and Hips)

Oxytocin

Substance P

Cholecytoskin

Vasopressin

Neuropeptide Y

Hypothalamis release hormones

Gases Family

(subtypes?: Nick’s Carbon)

Nitric oxide

Carbon monoxide

how are Amino acids NTs synthesized, what is their function?

they are not synthesized they come from food

function: builds proteins

(primary NT for this reason)

how are non amino acid NTs

synthesized, and where are they kept?

• made in the body: starts as metabolic precursors then converted to (non amino) NTs

• transporter proteins move them into vesicles

Describe the 2 ways NTs are synthesized and stored

• Amino acids from diet which are used to build proteins. Since so many the brain’s neruons uses them as main NT

• other NTs are synthesized in the body. converted from metabolic precursors into NTs. after being synthesized they are moved into vesicles by transporter proteins in membrane

How are Aminio acids and Amine NTs made?

enzymes convert precursor molecules into NT molecules in cytosol

transporter proteins put the NTs into vesicles in presynaptic terminal, where they are stored until released

describe how Neuropeptides get made?

a precursor peptide is synthesized in the cell’s rough ER (endoplasmic reticulum)

2. it is cut in 2 at goligi aparatus forming active NT

3. Secretory vesicles (large and dense) bud off the Golgi with NTs

4. Secretory granules take NT down the axon terminal where it is stored until used

Classfications of Neurons according to their NT (ergic)

a neuron that produces a neurotransmitter will be (NT name+ergic)

Glutamatergic: produces glutamate

GABAergic

Co-localization

some neurons produce more than one type of NT and co release them

explain how NT act as a hormone, use an NT as example

Yes, the same molecule can act as a neurotransmitter in the brain but also as a hormone elsewhere in the body

in the bloodstream it is a hormone

in the synapse it is a neuropeptide

ex. norepinephrine

Excitatory NT

define, name examples

increases the likelihood of depolarizing the membrane and firing an action potential

exs

Glutamate

Asparate

Glutamate

(family, made, effect, function, cons)

• Amino acid NT

• Primary excitatory NT

• helps with leaning, synaptic plasticity, and memory

• too much will overexcite and kill neurons

what does Inhibitory NT do? name exs

makes it less likely an action potential will be fired (hyperpolarizing the neuron)

• GABA

• Glycine

GABA

spell, family, made, effect, function, located?

Gama-aminobutyric acid is an

Amino acid NT
which neurons synthesize from glutamate

• found all over the brain

• its receptors lessen excitability and act as a sedative

Acetylcholine (ACH)

(family, structure, effect, function in diff NS)

• an amine in its own class

• chemically different since it has an acetyl molecule on its choline

• depending on the receptor ACH is excitatory or inhibitory

function:

• makes muscle contract when on *neuromuscular junctions

• Parasympathetic and Enteric NS (calming heartrate, increasing digestion)

• other CNS synapses: attention, memory, arousal

Cholinergic pathways

(define, types)

pathways which certain neurotransmitters flow

1. Basal forebrain → cortex and hippocampus

2. Brainstem → Thalamus and forebrain

describe cholinergic pathway:
Basal forebrain → cortex and hippocampus

(brain system involved, starting points, function)

goes from a subcortical area in the brain forebrain to the cortex and to the hippocampus

related to limbic system

ex. ACH released here will support attention learning and memory

includes starting points in basal forebrain:

nucleus basalis

medial septal nucleus

nucleus of diagonal band

describe cholinergic pathway:

Brainstem → Thalamus and forebrain

(funcitons, starting points)

Starts at brainstem goes to thalamus and forebrain

more related to arousal (sleeping and waking, activity of the thalamus

includes starting points at brainstem:

Pedunculopine nucelus and laterodorsal tegmental nucleus

Monoamines

(family, types)

subclass of amines, two types

Catecholamines

Indoleamines

Catecholamines (monoamine)

(family, class, precursor, types of NTs)

derived from tyrosine amino acid

processed by enzyme Ldopa which transforms it into

dopamine, then epinephrine, then norepinephrine

not enough tyrosine precursor wont have enough of rest of NTs

Tyrosine where does it come from?

comes from diet but can also be synthesized on body with amino acids

(high protein food)

Indoleamine (monoamine)

(family, class, precursor, types of NTs)

derived from tryptophan amino acid

melatonin and serotonin

Tryptophan where does it come from?

comes from diet mostly

Dopamine

(family, class, precursor, function)

a monoamine (derived from tyrosine)

function: movement, motivation, and reward

(affects more as well depends on context too)

Dopaminergic pathways

Mesostriatal pathway (motor control

Mesolimbocortical pathway

Mesostriatal pathway

(which NT, function, describe path, specifc regions, parkinsons)

a dopaminergic pathway involved with motor control

goes from substansia nigra in midbrain to the striatum (caudate nucleus + putamen)

since its related to motor control

neuron death leads to parkinsons diease

Dopamine reacting in different dopaminergic pathways (parkinsons, and schizophrenia)

those with parkinsons are treated with L-dopa which can be transformed into dopamine. needed since neurons in substansia nigra have died. but its not easy to control where dopamine is raised and if in mesolimbocortical pathway it could cause schizophrenia symps

whats a precursor?

first substance thats needed to synthesize / transform into other substances

Mesolimbocortical pathway

(which NT, function, describe path, specifc regions, schizophrenia)

a dopamergic pathway involved in reward, motivation and learning

goes from VTA in midbrain to the amygdala, nucleus accumbens, and cortex (insula) of limbic system

when high levels of dopamine → schizophrenia

VTA

(spell, location, function)

Ventral Tegmental area

next to substansia nigra (both major dopamine areas of the brain) has a large population of dopamine neurons

dopamine neurons travel from VTA to mesocortical and mesolimbic pathways

Norepinephrine, and Epinephrine

(family, class, precursor, function for each)

• synthesized from dopamine (precursor)

• aka noradrenaline and adrenaline

norepinephrine is the NT

epinephrine is a hormone

function:

• its released in the Sympathetic NS to cause fight or flight reaction

• related to mood, arousal, sexual behavior

• when it is a hormone (epinephrine in body) has stronger effects

Norandenergic pathways

(type of NT, path, brain regions, and epinephrine role)

pathways for norepinephrine

first released in the locus coeruleus in pons and lateral tegmental in midbrain

(goes to cerebellum. hippocampus, brainstem)

epinephrine released from adrenal glands

Serotonin (5-HT)

(family, class, precursor, function)

derived from tryptophan

function: sleep, mood, sexual behavior, and anxiety

Serotonergic pathways

(type of NT, made, path, brain regions, function)

serotonin is made in the raphe nuclei (cell bodies in the brain stem)

they gather in midline of brainstem and are exported to all areas of the CNS

it is key in the enteric NS because most serotonin is made in gastrointestinal tract which cant cross into CNS but regulates a lot of interior bodily function

Peptides as neuromodulators (recap)

what is it, how does it modulate?

NTs made up of long amino acid chains and has long lasting, slow effects that modulate. (not as precise)

it coexists with other NTs at the axon terminal stored in separate vesicles

acts on metabotropic receptors (g protein coupling)

Opioid peptides

(family, class, function, location)

in family of enkephalins (modulate pain response) and endorphins (modulate pain + reward, pleasure)

mimics effects of opioid drug like morphine

so it reduces pain

found in areas that process harm to NS aka pain (nociceptive) like periaqueductal gray)

Gut peptides

(family, class, function, location, exs)

modulates gut function, digestion, hunger, satiety (satiation)

ex. substance P, cholecystokinin, ghrelin

Oxytocin

(family, class, function)

NT involved with social bonding, trust, and maternal behaviour

as a hormone it helps stimulate utirine contraction during labor and, lactation during breastfeeding

Gas NTs
(made, process, function, ex)

or gasotransmitters

gas moelcuels that dissovle into the cytosol of cell when synthesized

where its produced:

made in dendrites (and other areas not axons)
not stored in vesicles

how it works:

no receptor binding it diffuses into the cell and out

can be a retrograde transmitter moving backward from postsynaptic neuron to presynaptic neuron

function:
synaptic plasticity, learning and blood flow

ex. nitric oxide