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
What membrane ion channel / receptors does ethanol decrease
Ca2+
Glutamate
NMDA
Ethanol has depressant action true/false
True
What effect does ethanol have on dopamine
Enhanced dopamine release in reward pathway
- DA released from ventral tegmental area and nucleus accumbens
Effects of acute ethanol intoxication
Slurred speech
Motor incoordination
Increased confidence
Effects of higher levels of intoxication
Euphoria & melancholy
Aggression & submission
Driving risk
What neurological syndrome can ethanol cause
Dementia
Partly due to thiamine deficiency
What is the cardiovascular effect of ethanol
Heat loss
What is the gastric mucosa effects of ethanol
Chronic gastritis
What is the diuresis effects of ethanol
Inhibition of ADH secretion
What is ethanols effect on the liver
Increased fat accumulation
Hepatitis
Hepatic necrosis & fibrosis
Why does ethanol cause fat accumulation in the liver
Release of fatty acids from adipose tissue
Impaired fatty acid oxidation due to metabolic loss by ethanol
What is used in aversion therapy for alcohol abuse
Disulfiram
Has a severe reaction with ethanol by preventing conversion of acetaldehyde to acetic acid (build up of acetaldehyde)
Causes flushing, panic, tachycardia
What are the beneficial effects of ethanol
Protective against atheroma formation
Increased plasma HDL
