chapter 6 Flashcards
what are the biogenic amines?
- dopamine
- norepinephrine
- epinephrine
- serotonin
- histamine
the nicotinic Ach receptor type?
ionotropic
the nicotinic Ach receptor at the neuromuscular junction is sensitive to which toxin produced by the kreit fish?
alpha-bungarotoxin
muscarinic Ach receptor type
metabotropic
muscarinic Ach receptor number of domains
7 helical membrane spanning domains
what are the ionotropic glutamate receptors?
- AMPA - larger
- NMDA - slower and longer
- Kainate - rise quick decay slow
AMPA receptor characteristics
- 4 subunits
- Y shaped
- tetrameric
- clam shaped ligand binding domain that shuts when binding occurs
NMDA receptor characteristics
- pore allows entry of Ca, K, Na
- Mg2+ blocks pore at hyperpolarized potentials
- gating requires co agonist glycine
- 2 glutamate binding subunits and 2 glycine binding subunits
- clamshell ligan binding domain
how many classes of metabotropic glutamate receptors?
3
characteristics of metabotropic glutamate receptors?
- transmembrane x 7
- dimers of 2 subunits w venus flytrap domain attached by cysteine linker
GABA/ Glycine are inhibitory or excitatory usually?
inhibitory
enzyme that creates GABA
glutamic acid decarboxylase (GAD) - requires cofactor in vitamin B6
2 types of GABA receptors and type of each
- GABAa = ionotropic
- GABAb = metabotropic
GABAa characteristics:
- main permeant ion = Cl-
- pentamers: 2 alpha, 2 beta, 1 gamma
- binds benzodiazepines (anxiety reducing), barbiturates, ethanol, and ketamine
GABAb characteristics
- works by activation of K+ and channels and blockages of Ca2+ channels
- heterodimers of B1 and B2 subunits
GABA main precursor
glucose
Glycine main precursor
serine by hydroxymethyltransferase
how is GABA activity terminated?
converted to succinate and led to TCA
how is glutamate activity terminated?
by excitatory amino acid transporters
glycine activity terminated by
glycine transporters
glycine receptor characteristics?
- pentamers, mix of 4 alpha and accessory beta
- blocked by strychnine
- ligand gated Cl- channels (ionotropic)
- Cl - inhibitory
the 3 catecholamines
- dopamine
- norepinephrine
- epinephrine
location of dopamine
corpus striatum
cause of Parkinson’s disease
degeneration of dopaminergic neurons of substantia nigra
dopamine involved in what behaviors
motivation, reward, reinforcement
how is dopamine removed from cleft?
uptake by Na+ dependent transporter DAT
how does cocaine exert its effects?
inhibits DAT, no reuptake of dopamine
what do amphetamines do?
inhibit DAT (no dopamine reuptake) and norepinephrine transporter (NET)
what type of receptors are activated by dopamine?
G protein coupled
Norepinephrine location
locus coeruleus with forebrain targets
norepinephrine involved in what behaviors
sleep and wake, arousal, attention, feeding
how is norepinephrine removed from cleft?
by norepinephrine transporter
type of receptor for norepinephrine
G protein coupled alpha and beta adrenergic receptors
epinephrine location
lateral segmental system and medulla
epinephrine involved in:
respiration and cardiac function
receptor type for epinephrine
alpha and beta adrenergic receptors
histamine location and involved in…
hypothalamus, arousal and attention, vestibular system, allergies
receptors for histamine
4 metabotropic receptors
serotonin location and involvement in….
raphe region of pons and upper brainstem, sleep and wake
serotonin removed from cleft by:
serotonin transporter (SERT)
many antidepressant drugs act on which transporter
serotonin transporter SERT
LSD mechanism
causes hallucinations by activation of many types of metabotropic receptors
ATP is released as a co transmitter in some instances and is removed from cleft how?
by enzymes that degrade it to adenosine
3 classes of purinergic receptors
- P2X receptors - ionotropic
- 2 types of G protein coupled receptors
5 categories of peptide neurotransmitters
- brain gut peptides
- pituitary peptides
- opioid peptides
- hypothalamic releasing hormones
- not easily classified
what is substance P ?
a brain gut peptide, that is a hypotensive agent, found in neocortex, hippocampus, GI tract
3 categories of opioid receptors
- endorphins
- enkephalins
- dynorphins
all neuropeptides use what kinds of receptor?
G protein coupled
receptor for endocannabinoids
CB1 receptor - G protein coupled
what is nitric oxide?
an unconventional neurotransmitter that is a gas signal and a 2nd messenger