Drug Dependence [9] Flashcards
What neurones are involved in the reward pathway
The mesolimbic dopaminergic neurones
What contributes to the reward feeling
Increase release or prevent uptake of DA in nucleus accumbens
There is evidence for a separate opioid-mediated pathways involving
5-HT and GABA
What is habituation
Withdrawal affects
What is the habituation mechanisms
Increased adenylate cyclase activity to compensate for acute inhibitory effect on cAMP
In habituation - what other pathways are increased
G-proteins & protein kinases
Increased activity of ion channels
Cells are more excitable
How is smoking addictive
Activation of nicotinic Ach receptors
Channel opening
Neuronal excitation
What is the difference in consequence with small / large doses of nicotine
Small doses - arousal
Large doses - the reverse
How do peripheral side effects of nicotine occur
Stimulation of autonomic ganglia & peripheral sensory receptors mainly in heart + lung
Causes autonomic responses
- tachycardia, increased GI output, increased arterial pressure etc
How does tolerance of nicotine arise
Desensitisation of nicotinic Ach receptors
How does dependence of nicotine arise
It causes excitation of the mesolimbic pathway & increased DA release in nucleus accumbens
What are the physical withdrawal symptoms of nicotine
Irritability, aggressiveness, sleep disturbance
- these can persist for 2-3 weeks but cravings last much longer
Harmful effects of smoking
Cancer
Coronary heart disease
Chronic bronchitis
3 treatments for smoking addiction
Nicotine replacement therapy
Varenicline
Clonidine
What membrane ion channel / receptors does ethanol increase
GABA
Nicotinic Ach
5-HT3
