Test 2: Indolamines/Acetylcholine Flashcards
5HT synthesis starts with the amino acid ____
tryptophan
Determines the rate of synthesis
rate limiting step
An irreversible inhibitor of 5HT
para-chlorophenylaline (PCPA)
What is the rate limiting step in 5HT production?
tryptophan hydroxylase converting tryptophan to 5HTP
___ packages 5HT into classical synaptic vesicles, provides means for releasing predetermined amount
vesicular monoamine transporter (VMAT)
5HT is released primarily by __ dependent mechanisms
Ca
5HT is [excited/inhibited] by auto-receptors on the synaptic terminal surface, dendrites, or somata
inhibited
5HT is inactivated by 2 different responses: __ and __
reuptake and metabolism
5HT is metabolized by __, creating __
monoamine oxidase (MAO); 5-hydroxindolacetic acid (5HIAA)
Network of 5HT cell groups projecting to the forebrain, midbrain, cerebellum, cord
B cell groups
all 5HT receptors are [metabotropic/ionotropic] with the exception of 1 subtype
metabotropic
The only excitatory ionotropic 5HT receptor subtype
5HT3
For the most part, 5HT is [excitatory/inhibitory]
inhibitory
What kind of 5HT receptors are concentrated in the hippocampus, septum, amygdala, and raphe?
5HT1A
5HT binding to 5HT1A receptors functions by two major mechanisms: ___, which inhibit adenylate cyclase and cAMP production, and __ channel opening, producing hyperpolarization
Gi coupled receptors; K+
What receptor subtype do anxiety meds and appetite/alcohol drive suppressant
5HT1A
Which 5HT receptor subtype are concentrated in cortex, striatum, and nucleus accumbens?
5HT2A
__ receptor subtype function is implicated in sensory perception and integration (thalamus)
5HT2A
5HT binds to 5HT2A by activating PI 2nd messenger systems which have two major consequences: __ and __
activates protein kinase C, increases release of cellular stores of Ca
5HT2A’s release of cellular stores of Ca may also reduce __ channel opening, which produces depolarization and therefore is __
K+, excitatory
Hallucinogenic drugs act as __ on __ receptors
agonists, 5HT2A
Ach is synthesized from two precursors: __ and __
choline and acetyl coenzyme A (acetyl CoA)
Ach’s rate limiting step is synthesis by __
choline acetyltransferase (ChAT)
The stimulation of ChAT is a [positive/negative] feedback mechanism
positive
Ach is packaged into small classic synaptic vesicles and ___ provides means for releasing predetermined amount
vesicular Ach transporter (VAchT)
Ach is released by __ dependent mechanisms (pre-synaptic potential)
Ca++
Animal and bacterial toxins influence __ release (ex: black widow venom)
Ach
Ach is metabolized by __ in the presynaptic terminal and on postsynaptic membranes
acetylcholinesterase
When Ach is metabolized, it becomes __ and __
choline and acetic acid
Ach uses __ for reuptake, which shuttles __ from synapse back to terminal (necessary for rapid removal of precursor from synapse)
choline transporter; choline
Ach reuptake is blocked by the drug ___
hemicholinium-3 (HC-3)
___ Ach cells innervate many brain sites
projecting
the two main subtypes of Ach receptors
muscarinic and nicotinic
Ach receptor subtype found on muscles, ganglia (PNS) and certain CNS regions
nicotinic
nicotonic Ach receptors are [metabotropic/ionotropic]
ionotropic
nicotinic Ach receptors are [stimulatory/inhibitory]: ion channel for __ and __
stimulatory; Na and Ca
continuous agonist exposure on nicotonic Ach receptors causes __
desensitization
Is desensitization of nAch receptors reversible?
Yes
because of persistent depolarization, a cell cannot become active until an agonist is removed and the membrane is repolarized
depolarization blockade
__ Ach receptors are widely distributed in the CNS (cortex, hippocampus, thalamus, striatum, basal forebrain)
muscarinic
__ Ach receptor function is important in CNS for cognition (cortex and hippocampus), motor behavior (striatum), and drug reward (basal forebrain)
muscarinic
In the PNS, __ Ach receptors are ocated in heart, visceral smooth muscle, bronchioles, and secretory organs
muscarinic
