L13 - Socially used and abused drugs

Question 1

Social drugs:

Answer 1

Are a pharmacologically heterogeneous group so act on a wide variety of receptors.
Have pleasurable effects.

Question 2

How do they evoke pleasure:

Answer 2

Activates dopaminergic reward pathways in brain that run from VTA to nucleus accumbens. (in forebrain).

Question 3

Activation of reward pathway:

Answer 3

Can be direct or indirect. Direct activation where increase dopamine in nucleus accumbens. Indirect activation by disinhibiting GABA which inhibit NT. So dopamine can fire at high rate as they are disinhibited so no longer inhibited by GABA.

Question 4

Problems with drugs:

Answer 4

1. Addiction
2. Psychological so craving
3. Desire for drug can dominate lifestyle
4. Criminal behaviour as habit.
5. Harms individual - toxicity

Question 5

Cigarette Smoking:

Answer 5

Psychoactive stimulant and relaxant. 
Aiming for euphoria, increased alertness and concentration. Relaxation. 
Natural plant source. 
Has nicotine which causes addiction.
Has many toxic chemicals in it.

Question 6

Nicotine:

Answer 6

Agonist at nicotinic ACh receptors. Configuration changes and pore opens. Causes Na influx.
In periphery: Excite autonomic ganglia and cause adrenaline release from adrenal medulla. Causes vasoconstriction and increases blood pressure.
In CNS: causes neuronal excitation. Releases many NT including dopamine, ACh and serotonin (causes relaxation).

Question 7

Toxic effects of smoking:

Answer 7

CO displaces oxygen forms carboxyHb. Causes ischaemic heart disease.
Nicotine is a vasoconstrictor and increases platelet aggregation. Increased risk of thrombosis. Poor blood circulation.
Tar and irritants - contains toxic chemicals like formaldehyde and benzopyrene. Increased chances of lung cancer, Parkinson’s, premature births.

Question 8

Morbidity:

Answer 8

Greatest incidence of morbidity is due to smoking.

Question 9

Cannabis:

Pharmacology:

Toxicity:

Answer 9

Most used illegal drug. Can be stimulant, depressant or hallucinogenic. Euphoria, relaxation, heightened sensory awareness. Made from natural product.

Pharmacology:
delta-9-THC activate endogenous CB1 and CB2 receptors in brain and periphery. Inhibit GPCR so leads to inhibition of Ca channels opening. So inhibits NT release (e.g. Ach, GABA and NA).

Toxicity:
Vasodilation (bloodshot eyes), drowsiness and confusion.
Cancer, confusion and memory impairment, psychosis, reduced immune responses, growth retardation in foetus. No. of related deaths per annum = 1

Question 10

Ecstasy:

Pharmacology:

Toxicity:

Answer 10

Stimulant and empathogenic drug. Aim for euphoria, arousal, empathy, endurance, self confidence. Made synthetically. MDMA is an amphetamine.

Pharmacology:
Displaces 5-HT from vesicle so leak out. Also blocks reuptake pump to prolong 5-HT action. Increase in NA and DA. 5-HT can stimulate receptors elsewhere.

Toxicity:
Inability to regulate body temp. Reduced blood Na. Increases ADH secretion so water retained. Post ecstasy, exhaustion, irritable, low mood (low 5-HT).
Damage 5-HT terminals and can cause depression and anxiety.