How Nicotine Interacts with the Brain

1
Lesson 3

• How Nicotine Interacts with the Brain

2
A look at the brain

• Different parts of the brain are involved in
  different functions, like vision, movement,
  thinking, memory.

3
The Reward Pathway

• The reward pathway is a neural pathway used for
  reinforcing behaviors that are important for
  survival.

Nicotine also stimulates the reward pathway.
This feels good!
VTA
NA
4
Dopamine is the neurotransmitter in the reward
pathway

• Stimulation of neurons in the VTA area results in
  release of dopamine in the NA (emotional center)
  and the prefrontal cortex (thinking).

VTA
NA
5
How does nicotine affect neurotransmission?

• Nicotine binds special receptors on the dendrites
  of certain neurons.
• An electric impulse travels down the axon.
• Dopamine is released at the axon terminals into
  the synapse.
• Dopamine binds receptors on the next neuron.
• This may lead to an electric impulse down second
  neuron.

nicotine
Synapse
6
How does nicotine interact with the reward
pathway?
This feels good!
Nicotine binds to receptors on neurons in the VTA.
An electrical impulse travels down the neuron
axon.
Dopamine is released at axon terminals in the NA
and prefrontal cortex.
VTA
NA
Dopamine binds to dopamine receptors on other
neurons.
This leads to the rewarding effects of smoking,
such as relaxation, a buzz, or an increased
ability to focus.
7
What is the impact of nicotine interacting with
the reward pathway?

• Addiction!

8
What genes might be involved in variation in
smoking behavior?
Nicotine receptors
Dopamine receptors enzymes that make or break
down dopamine
Enzymes involved in nicotine breakdown
9
What genes are included in the smoking behavior
study?

• Two regions in the dopamine receptor gene (DRD2),
  which codes for a protein that binds dopamine,
  found on the dendrites of receiving neurons
• One region in the dopa decarboxylase gene (DDC),
  which codes for a protein involved in dopamine
  synthesis, found in the axons of neurons that
  release dopamine

DRD2