L8 - catecholamines and psychomotor stimulants

what are the three main catecholamines

dopamine

norepinephrine/noradrenaline

epinephrine/adrenaline

tyrosine hydroxylase

the rate-limiting enzyme in catecholamine synthesis. it converts tyrosine into L-dopa (which then goes into dopamine then norepinephrine and epinephrine)

what is the difference between d1 type and d2 type dopamine receptors

d1 stimulate activity but d2 inhibit acticity

dopamine transporter

A transporter on dopamine nerve terminals that removes dopamine from the synapse by reuptaking it into the presynaptic neuron.

how does cocaine increase dopamine transmission

cocaine blocks DAT, this prevents dopamine reuptake and increases the amout and duration of dopamine in the synapse

how does amphetamine increase dopamine transmission?

amphetamine enters through DAT as it has a similar structure to dopamine. disrups dopamine storage through VMAT and causes DAT to work in reverse, releasing dopamine into the synapse

nigrostriatal pathway

dopamine pathway from substantia niagra to dorsal striatum. involved in movement and psychostimulant - induced stereotyped behaviours.

mesolimbic pathway

dopmaine pathway from VTA to the nucleus accumbens. involved in reward, locomotor activity and drug-self administration.

what dopamine transporter occupancy is associated with experiencing a subjective cocaine high

approx 40 to 60% DAT occupancy

MDPV

a synthetic cathinone found in some bath salts. has powerful cocaine like stimulant effects and can produce greater dopamine increases and behavioural activation than cocaine.