Lecture 17- Nicotine 1 Flashcards
(16 cards)
What are the health and economic impacts of Nicotine?
Can lead to premature death, Gov spends +£17 billion on treating related illnesses.
What is involved in the tobacco substance
Nicotine biosynthesis takes place in the roots of tobacco plant and accumulates in the leaves.
-The toxicity of nicotine helps prevent the plant from being eaten
What is the pharmacology of Nicotine?
-Cigarette contains 6-11mg but only 1-3mg is absorbed.
-Nicotine attaches to tar molecules which are acidic and make conditions more suitable for nicotine absorption across lung alveoli into blood stream.
What form of nicotine reaches brain fastest and why?
Inhalation (smoking) due to rapid lung absorption and direct arterial transport.
Is nicotine an antagonist or agonist and at which receptor?
Agonist
At nicotinic acetylcholine receptors (nAChRs).
What is the neurotransmitter acetylcholine (ACh) ?
It is a ‘neuromodulator’ which can influence activity in target cells and plays role in learning and intellectual function.
What happens with Nicotine in the neural pathway?
When nicotine activates ACH neurons in the pedunculopontine nucleus (PPT) this excites the dopamine-producing cells in the VTA. As a result ,nicotine increases dopamine release in the mesolimbic pathway, specifically from the VTA to nucleus accumbens.
-This dopamine surge is believed to play a role in the development of addiction.
What did Fa et al (2000) say about dopamine activity in VTA?
Rats were administered tobacco smoke and found increased activity, but dopamine activity reduced when administered with nicotinic receptor (nAChRs) antagonist Mecamylamine.
What are the 2 susceptibility factors?
Metabolism
Age of first exposure
How is nicotine metabolism a susceptibility factor?
Differences in metabolism due to genetic variations. Slower metabolism means need to smoke less cigarettes so less likely to develop dependence.
How is age of first exposure a susceptibility factor?
Usage is higher in those who adopted habit earlier. Levin et al (2003)- Adolescent rats worked harder for nicotine and took larger amounts than adult rats.
What is the rate of nicotine dependence and why?
60% of current smokers meet DSM criteria for dependence.
But dependence is not inevitable from exposure, you need interaction between exposure and individual vulnerability.
What impacts withdrawal effects?
ACh receptors become desensitised after prolonged exposure which leads to effects when stopping: Cravings, irritability, concentration + sleeping difficulties
How do you relapse with nicotine?
Almost 100% of relapses occurred when cigarettes were available and allowed suggesting situational cues for drug availability and acceptability play role in maintenance drug use.
What is nicotine replacement therapy?
Provides nicotine in an alternative form to help reduce withdrawal effects, making it easier to quit smoking.
Does this by maintaining ACh receptor occupancy but may lead to transfer of dependence rather than completely eliminating addiction.
What is bupropion in nicotine replacement therapy?
Reduces emotional effects of withdrawal by inhibiting reuptake of dopamine and noradrenaline.
