Lecture Notes: Dopamine Pathways and Antipsychotic Drugs

Introduction

• Presenter: Charlotte
• Topic: Dopamine pathways in the context of antipsychotic drugs
• Objective: Understanding how antipsychotics work to control schizophrenia symptoms and their side effects

Dopamine and Antipsychotics

• Dopamine: Primary neurotransmitter targeted by antipsychotics
• Antipsychotics: Generally dopamine antagonists (reduce dopamine levels)

Dopaminergic Pathways in the Brain

There are four dopaminergic pathways affected by antipsychotic drugs:

1. Mesolimbic Pathway

• Function: Transmits dopamine from the midbrain to the ventral striatum
  • Includes the nucleus accumbens
  • Associated with motivation, emotions, rewards
• Role in Schizophrenia:
  • Overactivation leads to positive symptoms (hallucinations, delusions, thought disorder)
• Antipsychotic Action: Reduces dopamine in this pathway to alleviate positive symptoms

2. Mesocortical Pathway

• Function: Transmits dopamine from the midbrain to the prefrontal cortex
• Role in Schizophrenia:
  • Hypo function (reduced firing) is linked to negative symptoms (apathy, low motivation, social withdrawal, self-neglect)
• Pathway Visual: Seen running from the ventral tegmental area to the prefrontal cortex

3. Nigrostriatal Pathway

• Function: Transmits 80% of the brain’s dopamine
  • Runs from the pars compacta of the substantia nigra to the caudate nucleus and putamen
• Side Effects: Inhibition can lead to extrapyramidal side effects, especially with first-generation antipsychotics
  • Side effects include dystonia, akathisia, Parkinsonism, tardive dyskinesia

4. Tuberoinfundibular Pathway

• Function: Transmits dopamine from the hypothalamus to the pituitary gland
• Role: Dopamine inhibits prolactin
• Side Effects: Blocking dopamine results in hyperprolactinemia
  • Side effects include breast enlargement, galactorrhea, reduced libido, erectile dysfunction

Conclusion

• Overview: Understanding the dopamine pathways helps comprehend the effects and side effects of antipsychotic drugs in treating schizophrenia.
• Further Engagement: Encouragement to connect on social media and subscribe to learn more about brain-related topics.