AO1

• What does nicotine do?

  Stimulates the release of dopamine, increasing the level of dopamine in the brain and stimulating dopamine receptors on neurons. This provides feelings of pleasure and reception
• What happens once the dopamine is removed from the synapses?

  Feeling of pleasure and relaxation disappears. IN order to regain it, the person wants to take more of the substance
• If nicotine’s taken regularly, the body expects it and reduces the amount of dopamine that’s released naturally
• Nicotine is a psychoactive chemical in cigarettes
• Nicotine enters the blood when it is inhaled and when it arrives in the brain it activates nicotine acetylcholine receptors (nAChR)
• When nAChRs are activated by nicotine molecules, the neuron transmits dopamine
• What happens after nAChRs are activated by nicotine molecules and neurons transmit dopamine?

  Immediately followed by shutdown. Within miliseconds nAChRs shut down and temporarily cannot respond to any neurotransmitters .
• What happens during shutdown?


  The neuron is said to be desensitised. This leads to downregulation, a reduction in the number of active neurons because fewer of them are available
• What is the desensitisation hypothesis?

  Nicotine stimulates nicotinic receptors primarily located in ventral tegmental area (VTA) of the brain. This causes dopamine to be transmitted along the mesolimbic and mesocortical pathways to the nucleus accumbens and the frontal cortex. Dopamine is then released into the frontal cortex creating rewarding effects
• What is the first step of dopamine creating a pleasurable effect?

  nAChRs are concentrated in the ventral regimental area (VTA) of the brain. When these naChRs are stimulated by nicotine, dopamine is transmitted along the mesolimbic pathway to the nucleus accumbens (NA). This triggers the release of more dopamine from the NA into the frontal cortex
• What is the second step of dopamine creating a pleasurable effect?

  At the same time, dopamine is also transmitted along the mesocortical pathways to be released directly into the frontal cortex. The mesolimbic and mesocortical pathways are part of the brain’s dopamine reward system.
• What is the third step to dopamine creating a pleasurable effect?

  Nicotine powerfully activates the brain‘s dopamine reward system and results in pleasurable effects. These effects become associated with smoking through operant condition
• What happens as long as a person is smoking?

  nAChRs are continually desensitised
• When a person does not smoke for a prolonged period (e.g. when they are asleep) nicotine disappears from their body . Then nAChRs become functional again, so dopamine neurons resensitise and more become available (upregulation)
• Explanation for withdrawal

  During resensitisation nAChRs become overstimulated by ACh (because there is no nicotine to bind with them). nAChrs are at their most sensitive at this point. This is why smokers often describe the first cigarette of the day as the most enjoyable as it strongly reactive the dopamine reward system
• How does dependence and tolerance develop?

  The smoker avoids unpleasant physiological and psychological withdrawal states by having another cigarette. But this means there is a constance cycle of daytime downregulation and night-time upregulation and this creates long-term desensitisation of nAChRs. Continuous exposure of nAChRs to nicotine causes permanent changes to brain neurochemistry- a decrease in the number of active receptors. Tolerance develops as a smoker has to smoke more to get the same effects
• What neurotransmitter plays a key role in all nervous system activity?

  Acetycholine (ACh). This means there are ACh receptors on the surfaces of many neurons in the central nervous system. One subtype of ACh receptors is called nicotine acetycholine receptor (nAChR). Thesse receptors are special because they can be activated by ACh or nicotine