Expl for nic add: brain neurochem

Question 1

Nicotine effects:

Answer 1

Tranquilisation, decreased irritability, increased aletrness and improved cognitive functioning.

Less evident in regular smokers who develop a tolerance

Nicotine paradox: it has both stimulant and relaxation effect

Question 2

Dopamine and the brain’s reward pathways

Answer 2

Nicotine is absorbed through the lining of the mouth and nose and by inhalation in the lungs.
After inhalation, nicotine reaches peak levels in the bloodstream and the brain in less than 10 seconds.

Nicotine becomes addictive because it activates areas of the brain that regulate feelings of pleasure (the reward pathways of the brain)

Nicotine attaches to neurons in a region of the brain called the ventral tegmental area (VTA)
These neurons trigger release of the neurotransmitter dopamine in a nearby brain region called the nucleus accumbens (NAc).
As well as directly influencing the NAc to release dopamine, nicotine also stimulates the release of the neurotransmitter glutamate, which triggers additional release of dopamine. This release of dopamine produces pleasure and a disposition to repeat the behaviours that led to it. It is this pleasure and the drive to repeat the process that leads to addiction.

Question 3

Glutamate, GABA, MAO

Answer 3

Glutamate: speeds up the activity of neurons
GABA: slows down neuron activity

Nicotine causes glutamate to speed up dop release, but nicotine also prevents GABA from slowing it down after dop levels have been raised

This combo of dopamine release and inhibition of GABA results in an increase in dopamine and amplification of the rewarding properties of nic

Cigarette smoke also contains an unknown substance that blocks the action of an enzyme called MAO.

MAO: responsible for breaking don dopamine after it has had its effects
Blocking MAO results in even higher dopamine levels, strengthening the smoking habit by maintaining the feelings of pleasure.

Question 4

The development of nicotine addiction

Answer 4

Bc the effects of nicotine disappear within a few minutes, creates a need to continue the intake of nic throughout the day in order to get the dopamine rush.

However, continued activation of the dopamine-enhancing neurons changes their sensitivity to nic, resulting in tolerance, dependence and addiction.

Question 5

AO3: brain neurochem nic add

Answer 5

str: support for nic-dop link
str: support for glutamate and GABA
str: parkinsons
lim: gender

Question 6

brain neurochem nic add str: support for nicotine-dopamine link

Answer 6

Support for the link between nicotine and dopamine comes from research on the effects of an epilepsy drug (gamma-vinyl GABA - GVG)

Paterson and Markou: found that GVG reduces the surge of dopamine in the NAc that occurs after taking nicotine. This reduces the addictive tendencies of nicotine and other drugs that boost the brain levels of dopamine, such as cocaine and heroin.

By counteracting any pleasurable experiences that may be gained by the increase in dopamine, this drug may offer an alternative way of treating nicotine addiction.

Question 7

brain neurochem nic add str: support for glutamate and GABA

Answer 7

The role of glutamate and GABA in nicotine addiction is supported by a study of nicotine-dependent rats

D’Souza and Markou: blocked transmission of the neurotransmitter glutamate, which resulted in a decrease in nicotine intake and nicotine seeking in the animals.This is because glutamate usually enhances the dopamine-releasing effects of nicotine. Nicotine intake and nicotine seeking aso decreased when GABA neurotransmission was enhanced. This is because the inhibition of GABA typically keeps the dopamine effect going for longer.

These findings are consistent with explanations of the action of these two neurotransmitters during smoking and reinforce their role in the development of nicotine addiction.

Question 8

brain neurochem nic add str: nic and Parkinson’s

Answer 8

Further support for the link between nicotine and dopamine comes from the treatment of Patients with Parkinson’s disease

PD is a progressive neurodegenerative disorder, characterised by a gradual loss of dopamine-Producing nerve cells.

Fagerstrom: treated two elderly PD patients with nicotinessed and patches. They found significant changes in symptoms that were attributed to the increase levels of dopamine caused by the nicotine administration.

This suggests that nicotine may have a neuroprotective function against the development of PD and may also be beneficial in its treatment

Question 9

brain neurochem nic add lim: gender diffs

Answer 9

Nicotine affects men and women differently

Cosgrove: studied the brains of men and women using PET scans in order to measure the changing levels of dopamine when smoking.

They observed the dopamine levels of 16 long-term cigarette smokers (eight men and eight women) while smoking a cigarette.

For women, there was a rapid and strong dopamine effect in an area of the brain called the dorsal putamen, whereas men only had moderate to low activation in this area.

Men had a rapid and strong activation effect in the ventral striatum, whereas women were only mildly affected.

Cosgrove et al. concluded that this finding supports the claim that men and women smoke for different reasons - men for the nicotine effect itself, and women to relieve stress and manage mood.