neural pathways

Question 1

examples of DSM5 criteria for substance abuse disorder

Answer 1

use in larger amounts or during longer periods than initially intended

Persistent desire or unsuccessful attempts to restrict use

Great deal of time devoted to procuring, consuming, and recovering from use

Craving, strong desire to use

Recurrent use resulting in failure to fulfill obligations at work, school, or home

Continued use despite persistent social problems caused by use

Important social or professional activities given up in favor of use

Recurrent use in situations in which it is physically hazardous

Continued use despite knowledge of substance-related problems

Tolerance

Withdrawal

Question 2

Examples of historical development of animal models of reward and addiction

Answer 2

1950s - animals repeated acts that were associated with electrical stimulation of the brain

1960s - rat brain regional studies and role of catecholamine turnover

1970s - link between catecholamines and reward

Question 3

5HT synthesis pathway

Answer 3

Tryptophan to 5-hydroxy-L-tryptophan by tryptophan hydroxylase (TPH)

to 5-HT by amino acid decarboxylase (AADC)

to N-acetylserotonin by SNAT

to melatonin by ASMT

Question 4

Catecholamine enzyme pathways

Answer 4

L-tyrosine to L-DOPA by tyrosine hydroxylase (TH)

to dopamine by AADC

to adrenaline by DBH

to L-noradrenaline by PNMT

Question 5

Transporters involved

Answer 5

NET
DAT
SERT

PMAT

VMAT1
VMAT2

Question 6

Dopaminergic pathways in reward

Answer 6

Dopaminergic cell bodies from the ventral tegmental area and substantia nigra pars compacta

VTA acts on the nucleus accumbens shell which is particularly implicated in reward pathways associated with addiction. also acts on pre-frontal cortex

SNC acts on the dorsal striatum (caudate nucleus and putamen)- dysfunction of which is associated with PD

Dopamine acts at caudate nucleus/putamen for locomotor control, pre-frontal cortex for emotion and executive function, and NAc for anticipation of reward and addiction.

Question 7

Rodent model of drug addiction

Answer 7

rodent conditioned place preference.

animals are habituated in a box split in two with a removable partition. one side of the box they are given drug, and other side vehicle. after 2 days, partition is removed and the animal is placed in the middle.

the time each animal spends in each chamber is then recorded.

Drug self administration is another model. drug is administered after the animal performs a task (e.g., lever press). can also be done with drug discrimination, where one lever press gives vehicle and different lever gives drug. can assess dose dependant abuse potential