CNS neurotransmitters Flashcards
what are the 2 major types of neurotransmitters?
small molecules ( classic neurotransmitters) and neuropeptides
name the three main types and examples of other small molecule ( classical neurotransmitters)
acetylcholine (ACh), amino acids ( glutamate, GABA, glycine), biogenic amines ( dopamine, norepi, and epi)
what is special about the amino acid neurotransmitters, glutamate, GABAand glycine?
they are in every synapse glutamate is excitatory, and GABA and glycine are inhibitory
what are peptide neurotransmitters important for?
transmission and blocking of pain.
what does removal of neurotransmitters from the synapse do?
terminate synaptic transmission
the concentration of neurotransmitter w/in the synaptic cleft is tightly controlled via regulation of what 4 processes?
neurotransmitter synthesis, packaging, release and removal
where are neuropeptide neurotransmitters made?
in the ER
where are small molecule neurotransmitters made?
in the presynaptic terminal
ligand gated ion channels are?
ionotropic
G-prootein coupled channels are?
metabotropic
Metabotropic neurotransmitters are ___________ than ionotropic transmitters
slower
1 alpha and 1 beta are required to be what type of receptor?
GABA
iontoropic receptors have how many subunits that contain how many transmembrane domains?
iontoropic receptors are usually 4-5 subunits that contain 3 or 4 transmembrane domains
metabotropic receptors have how many transmembrane domains?
7
what are the major biogenic amine neurotransmitters?
dopamine, norepinephrine, serotonin
what is the major neurotransmitter in the neuromuscular junction of the peripheral nervous system and where else is it the major neurotransmitter?
acetylcholine which is also the major neurotransmitter in the parasympathetics
where is acetylcholine synapse in the peripheral nervous system?
in the ganglia of the visceral motor sys
what are the fmcs of Ach in the CNS?
attention, arousal, reward plasticity, enhances sensory fnc upon waking
what is damage to the Ach sys ( cholinergic sys) in the CNS associated w/?
memory deficits in alzheimer’s
what does acetylcholinesterase do?
it cleaves acetylcholine to acetate and choline ( this occurs in the synaptic cleft in the CNS and in the basal lamina in the periphery
where is achetocholine degraded?
in the synaptic cleft
sarin gas and other nerve gases and insecticides which inhibit acetylcholinesterase do what?
cause Sch to accumulate resulting in continued depolarization of the postsynaptic cell and leads to muscle paralysis at the neuromuscular junction.
are acetylcholine receptors ionotropic or metabotropic?
there are both metabotropic (muscarinic)and ionotropic (nicotinic) Ach receptors
where do ionotropic (nicotinic) acetylcholine receptors act?
in the periphery in the neuromuscular junction and also in the CNS
where do metabotropic ( muscarininc) receptors act?
they mediate most Ach effects in the brain
and they are involved in autonomic effector organs in the heart, smooth muscle etc.
name 2 metabotropic Ach receptor antagonists.
atropine ( cause pupil dialation)
scopolamine ( motion sickness)
what is myasthenia gravis?
an autoimmune disease in which pts have antibodies against the muscle nicotic ( ionotropic) Ach Receptor leading to decreased receptors in the postsynaptic membrane, expanded synaptic cleft, and shallow junctional folds ( see pg 145)
what are the symptoms of myasthenia gravis?
weakness, fatiguability in the arms and legs, difficulty speaking and swallowing, chewing , diplopia, and ptosis
how do you treat myasthenia gravis?
by giving CHOLINESTERASE INHIBITORS to prevent the sparse number of Ach receptors the pt has from breaking down.
or THYMECTOMY surgically remove the thymus
or CORTICOSTEROIDS
or IMMUNOSURPRESSANTS - to decrease the autoimmune response to AchRs
What is the most prominent transmitter for normal brain fnc (CNS)?
glutamate
and in crease in extracellular glutamate can lead to ?
excitotoxicity causing neurons to over excite and die
excitotoxicity of glutamate is seen in which medical problems or disease?
strokes, hypoglycemia, trauma, and repeated intense seizures
can glutamate cross the blood brain barrier?
no but glutamine can
what happens to glutamate in glial cells?
they are converted to glutamine ( for transport out of cells) which prevents the excitotoxicity from occurring
what are 3 types of glutamate receptors?
NMDA, AMPA and Kainate
what are 3 unique properties of NMDA compared to the other glutamate receptors?
- ca2+ can pass through it
- ion flow is voltage dependent because of the Mg2+ binding
- glycine binding is required to the open channel
where is GABA used in the CNS
in 1/3 of brain synapse , used in interneurons and purkinje fibers of the cerebellum
where is glycine used in the CNS?
at synapses in the spinal cord.
decreased GABA function can cause?
epilepsy
excess glycine can cause ?
neonatal disease characterized by lethargy and mental retardation.
glycine is made in nerve terminals from?
serine
GABA is made in nerve terminals from?
glutamate
where is glutamate made and used in the brain?
all over the place ( everywhere)
what are GABA receptor agonists used for?
they are tranquilizers and control epilepsy and can be used to treat panic disorders and anxiety.
what is an example of aGABA antagonists?
strychnine ( used in rat poison) it causes overactivity in spinal cord and brain stem leading to seizures
where are biogenic amines synthesized in the brain compared to GABA?
the amines are synthesized in specific layers but their receptors are more broadly distributed.
are biogenic amines released and removed from nerve terminals by the same means or different means?
by the same means ( they are les reliant on glial cells)
are biogenic amines greatly used in the brain?
they are used by relatively few neurons in the brain but they are very important in maintenance of mental health
a dopamine input to the corpus striatum is seen in what disease?
parkinson’s disease
cocaine interferes with the reuptake of what receptors?
dopamine receptors, therefore it raises dopamine levels
what is the major fnc of dopamine?
involved in ovation, reward and reinforcement ( this takes place in the midbrain dopamine system)
what is the minor dopamine fnc?
it is involved in emotional behavior ( localization of this involvement: in the projections to the cortex)
dopamine receptors act by?
activating or inhibiting adenlyl cyclase
why are ppl on amphetamines hyped up?
because it inhibits dopamine and norepi transporters causing an increase in release of them.
although it is hard to clinically distinguish norepi and serotonin how are they different?
norepi is mood activating
serotonin is mood altering
what is the dopamine hypothesis?
that too much dopamine leads to psychosis
what do anti-psychotic drugs block?
drugs block dopamine receptors
what do anti- anxiety drugs (MAO inhibitors and _________)?
block the breakdown of biogenic amines and therefore increase biogenic amines
and inhibitors of serotonin receptors
what are the 3 classes of anti depressants include?
MAO inhibitors ( biogenic amine receptor breakdown)
tricyclic anti-depressants ( block reuptake of Norepi)
serotonin reuptake inhibiotrs ( like prozac)
how are peptide neurotransmitters removed from the synaptic cleft ?
via degradation by peptidases
see chart on 165
see chart
