general Flashcards
Which AA is dopamine synthesized from?
Tyrosine
Which two enzymes convert tyrosine to dopamine, in correct order?
-which one is rate limiting?
tyrosine hydroxylase (rate limiting), DOP decarboxylase
Which enzymes can destroy dopamine?
- intracellular?
- extracellular?
- intra = MAO-A, MAO-B (mitochondrial enzymes)
- extra = COMT
presynaptic D2 receptor: functions?
“gatekeeper”
- allow DA release when they are not occupied by DA.
- inhibit DA release when DA builds up in synapse.
* negative feedback input
5 dopamine pathways in brain:
- mesolimbic
- mesocorticol
- nigrostriatal
- tuberoinfundibular
- innervates thalamus
tuberoinfundibular pathway
- from where to where?
- controls what?
hypothalamus to ant. pit controlling prolactin secretion.
mesolimbic pathway.
-projects from where to where?
ventral tegmental area of brainstem to limbic areas (ie. nucleus accumbens in ventral striatum).
mesolimbic pathway
-which roles?
- positive Sxs of schizo
- motivation, pleasure, reward
mesocorticol
-dorsolateral prefrontal cortex (DLPFC): function?
cognitive and some negative sxs of schizo
-from deficit of DA
mesocorticol
-ventromedial prefrontal cortex (VMPFC): function?
affective and other negative sxs of schizo
-from deficit of DA
prefrontal cortex
-how much D2 receptors?
very little
Two possible causes of neg. sxs in schizo?
- inadequate reward mechanisms (mesolimbic)
- inadequate DA in mesocorticol
Some people may lack mesolimbic reward center DA so they’ll use drugs to compensate but then too much dopamine in other mesolimbic pathways which lead to positive schizo sxs.
see front
nigrostriatal pathway
-axons from where to where
substantia nigra to basal ganglia/striatum
striatum composed of?
caudate and putamen
