may 13 - drug dependence

types of dependence

1. physical

   1. physiological change in brain

   2. pharmacological adaptation leads to tolerance

2. psychological

   1. involves emotions/motivation

drug addiction definition

drug0use is compulsive + out of control; component of physical dependence

heroin modifications

synthetically made to be more lipophilic = access to blood-brain barrier quicker

heroin/morphine moa

1. binds to neighbouring nerve

2. inhibits release of GABA

3. dopamine regulation disturbed and is increased

cocaine moa

1. blocks dopamine reuptake transporter

2. excess dopamine doesn’t go back to neuron

3. increases dopamine concentration

amphetamine moa

1. interferes with vesicular monoamine transporter

2. dopamine isn’t packaged correctly

3. leaves transporter unregulated and crosses synapse in unregulated ways

nicotine effect

cardiovascular vessels constrict initially then dilate = decrease in BP

nicotine moa

1. activates nicotinic acetylcholine receptors

2. causes receptor desensitisation + upregulation of nicotine receptor numbers

3. increases dopamine in nucleus accumbens

ethanol effects on brain

• down regulation of GABAa receptor = decreased Cl- output

• general depressant

• allows flow of dopamine in nucleus accumbens

• inhibits release of antidiuretic hormone

cannabis moa

1. binds to endogenous receptors (CB1 and CB2)

2. CB1 = dependent on site and most abundant in hippocampus

3. CB2 = exist in immune tissues and modulates pain