• Chemical or?drugs?can have a major impact on the functioning of the brain and nervous system
• Some prescription drugs can have a?beneficial effect?on those suffering from neurological disorders while recreational drugs can have a?damaging?or even fatal effect
• Many drugs have been found to produce a specific effect on?synaptic transmission
• They can have?different modes of action?such as:
  • Stimulating the release of a neurotransmitter
  • Providing the chemicals needed to synthesise neurotransmitters
  • Acting in the same way as a neurotransmitter by binding to the same specific receptor
  • Preventing the reuptake of the neurotransmitter by the presynaptic neurone

   

• Research is ongoing to further understand how several drugs work in the hopes that they can be used to?treat nervous disorders

Dopamine

• There are?many different neurotransmitters?that bind to?specific?receptor molecules
• They are often restricted to certain regions of the brain so that they have a specific function
• Some are excitatory and some are inhibitory
  • Excitatory neurotransmitters result in the?production?of an action potential
  • Inhibitory neurotransmitters?prevent?the production of an action potential. They do this by causing?potassium ions to leave the postsynaptic membrane

   

• Dopamine is a neurotransmitter involved in?muscle control
• Individuals that suffer from Parkinson's disease produce?insufficient amounts?of dopamine
• There are two types of drugs that are used to treat this disease
  • A dopamine?agonist?- produces the same effect as dopamine by binding to the same receptors
  • A dopamine?precursor?- this can be used to synthesise dopamine in the neurones

   

Morphine

• Dopamine also plays a vital role in?pain relief
• Chemicals called?endorphins?which are produced in the brain can stimulate the release of dopamine
• The endorphins attach to?opioid receptors?found on?presynaptic?neurones that release dopamine molecules
  • Exercise is a natural way to cause the release of endorphins

   

• Morphine?is a chemical very similar in structure to endorphins and so it can provide pain relief by stimulating the release of dopamine

Cocaine

• Cocaine also affects levels of dopamine
• It binds to the?dopamine transporter protein
• This prevents dopamine from binding to the transporter so it is?not able to move through the membrane?back into the presynaptic neurone
• As a result dopamine builds up in the synapses which can lead to feelings of?pleasure

Cannabinoids

• Cannabinoids are compounds found in cannabis
• Cannabinoid receptors are located in the?pre-synaptic?membrane?of?neuromuscular junctions
• When a cannabinoid molecule binds to its specific receptor, it?closes the calcium ion channels
• This leads to?decreased muscle contraction
• There is currently research investigating whether cannabinoids could be an effective drug in treating?multiple sclerosis?(MS)
  • MS is a disease that involves damage to the myelin sheaths of neurones. Sufferers struggle to control muscle contraction

   

MDMA

• MDMA?stimulates the release?of multiple neurotransmitters most notably,?serotonin
• Serotonin can affect people in many ways including their?mood, anxiety and sleep
• When an individual takes MDMA they may feel?extreme euphoria?and enhanced touch and bodily sensations