CYS loop receptors Flashcards
what are CYS-loop receptors
ligand gated ion channels
how many protein subunits make up a Cys-loop receptor
5 (pentamer)
define homo-oligimer
same subunit type
define hetero-oligimer
different types of subunits
where is the ligand binding site on nAChR
between subunit interfaces
what is the role of the Ach binding protein
takes up extra ACh
what ions are each receptors permeable to
K Na Ca
nAChRs are _________ ______________ channels
non specific cation
what does cation mean
positively charged ion
what does nAChRs modulate
fast synaptic excitation
What are some key members of the Cys-loop receptor family?
nAChRs
GABA(A) receptors
glycine receptors
5-HT3 receptors
name a autoimmune disorder associated with loss of nAChRs at neuromuscular junction
myasthenia Gravis
how is myasthenia Gravis diagnosed
typically through a blood test for antibodies of nAChRsn
name reversible competitive antagonists of AChE
neostigmine
pyridostigmine
edrophonium
what is congenital myasthenia syndrome
neuromuscular disorder caused by defects of several types at the neuromuscular junctionmutations that affect each receptor expression
name drugs that act as agonists on nAChRs
acetylcholine
nicotine
vareniciline
name a partial agonist for nAChR
varenicline
what is the main nAChR in the brain
a4B2
5-HT3 is permeable to which ions
Na K Ca
5-HT3 is a _________ _____________ channels
and modulate?
non-specific cation
fast synaptic excitation
how doe the structure of 5-HT3 compare to nAChR
identical
where are 5-HT3 receptors greatly expressed
and they modelate?
gut
peristalsis
name 5-HT3 receptor antagonists
anti-emetic drugs
eg. sterones (ondansetron)
name a target for positive allosteric modulators
GABA(A) receptor
name a neuro steriod allosteric modulator
allopregnanolone
what are benzodiazepines
positive allosteric modulators of synaptic GABA A receptors
mechanism of action of benzodiazepines
enhance GABA at GABA A receptor, increasing channel opening frequency causing a greater flux of Cl inside the cell so create a resistance to excitation
therefore slows down brain activity
what are benzodiazepines used to treat
anxiety
sleep disorders
epilepsy
name some common benzodiazepines
diazepam (long half life)
lorazepam (short half life)
midazolam (short half life)
how does propofol work as a anaesthetic
binds to a1B3y2 GABA A receptors
this generates a Cl influx hyperpolarisong the cell inhibiting AP and synaptic transmission
name anaesthetics that are positive allosteric modulators of GABA A receptor
thiopental
etomidate
propofol
the drugs that are non-bento hypnotics are positive allosteric modulators of GABA A receptors are known as
Z drugs
zolpidem
zopiclone
zaleplon
how do pregnant steroids relate to GABA A receptors
they are allosteric positive modulators of GABA A receptors
allosteric modulators of GABA A have what effect on channels
increase the opening time of the channels
how can neurosteriod levels be altered
alcohol and some SSRI antidepressants
neurosteriods can act at very ____ concentrations
low
give an example of a cell that has extra synaptic GABA A receptor
glial cells
synaptic GABA A receptors are __________ conductance
phasic
__________ conductance is mediated by activation of ?
tonic
extra-synaptic receptors
