About what percentage of dry tobacco weight is nicotine?
What was nicotine first used as, and what was the problem with this?
A pesticide. However, people absorbed it through their skin and became ill.
The delivery system for nicotine is fast due to…
Attached tar molecules which make the acidity suitable for absorption across lung alveoli.
In inhalators, why does nicotine have to be at such a high dose?
Because there’s no tar, so less of it is absorbed.
What criteria does the DSM use to define nicotine dependence?
Tolerance, withdrawal, dose escalation, difficulty cutting down, reduce other activities, use despite problems.
About what percentage of current smokers meet the DSM criteria for dependence, according to Donny and Dierker (2007)?
What are chippers?
Long term low-rate smokers (10% of smokers, according to Hyland (2005)).
At what age are people most likely to smoke?
What did Levin et al. (2003) find?
That adolescent rats self-administered more nicotine than adult rats.
Why might teenagers be more susceptible to nicotine addiction?
Perhaps the developing nervous system is particularly sensitive.
What does nicotine do to dopamine?
It’s an indirect dopamine agonist.
What did Gourlay and Benowitz (1997) find about the concentration of nicotine in arterial and venous blood?
It’s higher in arterial blood, which goes straight to the brain, meaning that it has a potent effect.
What pathways does nicotine primarily act on?
Cholinergic pathways - ACh.
Where are the major cholinergic projections?
The nucleus basalis and the peduculopontine nucleus (PPN) in the brainstem.
What are the functions of the nucleus basalis?
It regulates global functions in the cortex such as attention, arousal, motivation, memory and consciousness.
Where does the nucleus basalis project to?
What is the role of the pedunculopontine nucleus in the brain?
It regulates level of arousal, motivation, and processing of incoming information.
Where does the PPN project to?
How does nicotine interfere with acetylcholine transmission?
Nicotine has the correct molecular shape to act on ACh receptors - nicotinic cholinergic receptors.
What is ACh?
What does ACh play an important role in?
Learning and intellectual function.
In what disease is there degeneration of the ACh system?
How are ACh receptors believed to become desensitised?
Through chronic coupling, leading to withdrawal when nicotine is stopped.
What is thought to drive the rewarding effects of nicotine?
Increased activity in the target cells, particularly dopamine.