Last stuff for Exam 1: Ch 4 Neurotransmitter Flashcards
focuses on the basic chemical composition and processes of nervous system
neurochemistry
study of compounds that selectively affect the nervous system
- what do drugs do to nervous system
neuropharmacology
each neuron typically makes only _____ neurotransmitter
ONE
some neurons contain more than one type of neurotransmitter
- usually a neurotransmitter and a neuropeptide
co-localization
neurotransmitters and neuropeptides in the same vesicles, and both of them are released at the same time
co-release
stored individually in own vesicles
- can have diff sensitivities, release at same or diff times
co-transmission
2 terminal buttons, one in each
co-transmission
receptors determine whether a neurotransmitter is ______ or ______
excitatory or inhibitory
a single neurotransmitter may affect multiple
receptor subtypes
4 types of neurotransmitters
amine, amino acid, peptide, gas
amine neurotransmitters
acetylcholine, dopamine, serotonin
amino acid neurotransmitters
GABA, glutamate
peptide neurotransmitters
short chain amino acids, neuropeptides
gas neurotransmitters
soluble gases: nitric oxide, carbon dioxide
the first neurotransmitter recognized
acetylcholine
cholinergic
neurons that use Ach (acetylcholine)
where are acetylcholine neuron cell bodies located?
basal forebrain, striatum, pedunculopontine nucleus (PPN)
basal forebrain
multiple brain regions together, all over cortex
striatum
interneurons
pedunculopontine nucleus (PPN)
in brainstem, sends axons to cerebellum, pons, medulla, midbrain, striatum
functions of cholinergic system
neuromuscular junctions
autonomic nervous system
central nervous system
cholinergic: neuromuscular junction
muscles contract, move around
cholinergic: autonomic nervous system
role in both the sympathetic and parasympathetic
cholinergic: central nervous system
cognitive behavior: memory/attention
- balance and coordination (PPN)
acetylcholine synthesis
Ach formed from choline and acetyl CoA
what catalyzes acetylcholine synthesis
choline acetyltransferase (ChAT)
Ach is stored in _____ at axon terminals
vesicles
Ach moved into vesicles by ______
vesicular Ach transporters (VAchT)
Inactivation of acetylcholine
acetylcholinesterase (AChE) breaks Ach down into choline and acetate
- choline transported back into cell for reuse
- NO reuptake mechanism for Ach - 100% broken down
two ACh receptors
nicotinic and muscarinic
Nicotinic receptors are ____
ionotropic
when ACh binds, the channel opens and Na+ cations enter neuron or muscle cell
- mediate fast excitatory responses in CNS and PNS
nicotinic receptors
Muscarinic receptors are ____
metabotropic
5 types of muscarinic receptors
M1-M5
excitatory muscarinic receptors
M1, M3, M5
- when they bind it depolarizes cell causing an EPSP, making it more likely an action potential will occur
inhibitory muscarinic receptors
M2 and M4
two types of monoamine neurotransmitters
serotonin and dopamine
catecholamines
dopamine, epinephrine, norepinephrine
indoleamines
melatonin and serotonin
what amino acid is involved in catecholamine synthesis?
tyrosine
what enzymes are found in neurons that make dopamine?
tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC)
Rate limiting enzyme in catecholamine synthesis?
TH (tyrosine hydroxylase)
Neurons that synthesize dopamine also have dopamine _____
beta - hydroxylase (DBH)
Catecholamine pathway
TH turns tyrosine to LDOPA turned to dopamine by AADC
- if has DBH dopamine can be converted to norepinephrine
catecholamines are packaged into vesicles by the
vesicular monoamine transporters (VMAT)
if dopamine and norepinephrine are not protected they get broken down and can cause
sedation and depression
Inactivation of catecholamine
reuptake or enzymatic breakdown
dopamine transporter and norepinephrine transporter bring DA and NE back into cell
- molecules then repackage into vesicles or broken down
- repackaged by VMAT
reuptake of catecholamine
enzymatic degradation of catecholamine (2 enzymes)
catechol-O-methyltransferase (COMT) monoamine oxidase (MAO)
dopamine is found on neurons in
mesostriatal pathway (nigrostriatal)
important in motor control
- neuronal loss is a cause of PD
- axons go to striatum
mesostriatal pathway
dopamine mesostriatal pathway cell bodies located in the
substantia nigra
involved in reward, reinforcement, and learning
- abnormalities associated with schizophrenia
- motivation
- axons go to cortex, nucleus accumbens (limbic system)
mesolimbic and mesocortical DA pathways
where are the cell bodies of the mesolimbic and mesocortical da pathways located
ventral tegmental area (VTA)
Two families of dopamine receptors
D1 and D2
D1
excitatory
includes D1 and D5
D2
inhibitory
includes D2, D3, D4
DA auto receptors
inhibitory
D2 receptor
presynaptic only
cells producing norepinephrine are referred to as
noradrenergic
where are norepinephrine cell bodies located
brainstem:
- locus coeruleus in the pons
- lateral tegmental system in midbrain
where are NE axons?
brain - amygdala, hypothalamus
- modulates mood, arousal, sexual behavior
All NE and DA receptors are?
metabotropic
NE noradrenergic receptor subtypes (2)
alpha and beta
NE alpha receptors
alpha 1 and 2
NE alpha 1
excitatory
NE alpha 2
inhibitory
- the auto receptor when found presynaptically
Beta NE receptors
B1, B2, B3
ALL excitatory
serotonin
indolamine - has own biosynthetic pathway
where are most serotonin cell bodies located?
raphe nuclei (brainstem) - axons widely distributed in brain
5-HT is implicated in
sleep states, mood, sexual behavior, anxiety
how do antidepressants effect serotonin?
they increase 5-HT activity
what amino acid helps synthesize serotonin?
tryptophan
what is the first step of serotonin synthesis?
tryptophan hydroxylase (TPH) converts tryptophan to 5-hydroxytryptophan (5-HTP)
what is the second step of serotonin synthesis?
aromatic amino acid decarboxylase (AADC) converts 5-HTP to 5-HT
what does AADC do?
converts 5-HTP to 5-HT (serotonin)
converts LDOPA to dopamine
serotonin is transported into vesicles by
VMAT 2 (vesicular monoamine transporter)
serotonin inactivation 2 ways
reuptake, enzymatic breakdown
5-HT removed from synaptic cleft by 5-HT transporter (SERT)
reuptake of serotonin
selective serotonin reuptake inhibitors (SSRI)
antidepressants
- block serotonin reuptake, lets it float in synapse longer
breakdown of 5-HT is catalyzed by
monoamine oxidase (MAO) like NE and DA
receptor families with inhibitory effects
5-HT1 and 5-HT5
only ionotropic receptor
5-HT3
serotonin auto receptor
5-HT1A