Dopamine Pathways in the brain by Tosin

Dopamine Pathways in the brain by Tosin

1. Mesolimbic

   • Physiology: Projections from VTA (A10) to N. Ac (the Olf Bulb and Amgydala also)
     • Motivation, Emotion, REWARD!
       • Regulates these behaviours
       • Overactivity = Positive Symptoms of Szh
         • These include Delusions, Hallucinations and Thought Disorder and other Psychosis (reality testing is impaired) Furthermore = Catatonia (immobility/ non-purposeful movement)
   • D2 Antagonism Here = Alleviate Positive symptoms in Szh
     • Underactivity of this results = Antipsychotic Drug MOA

2. Mesocortical

   • Physiology: Projections from VTA (A10) to Prefrontal Cortex (PFC)
     • Dorsal Lateral PFC = Cognitive Functions
       • Cognitive Deficits in Szh
     • Ventral Lateral PFC = Emotions and Affect
       • Overactivity = Negative Symptoms of Szh
   • D2 Antagonism here = Alleviate Szh Symptoms

3. Nigrostriatal Pathway

   • Physiology = Projections from Substantia Nigra (A9) to Striatum (caudaute nuclues and putamen)
     • Controls Movement indirectly - Overactivity = Tardive Dyskinesia & Underactivity = Parkinsonism
       • See Basal Ganglia Pathways! Involved in preventing non-purposeful movement
       • Parkinsonism = Movement disorder & clinical syndrome caused by lesions/damage to Basal ganglis'a Substantia Nigra
   • D2 Block = Antipsychotic use side affects
     • In particular the Extrapyramidal side effects = movement disorders
     • These disorders involve involuntary movements 

4. Tuberoinfundibular

   • Physiology = Projections from Hypothalamus (arcuate and periventricular nuclei) to infundibular region in medial eminence
     • From one part of the hypothalamus to the other
     • Portal circulation between Medial eminence and Anterior pituitary = Dopamine released here
     • Dopamine inhibits Prolactin release
     • Hyperactivity = Too little Prolactin
     • Underactivity = Too much Prolactin
       • So D2 Blockade = Hyperprolactineamia
       • This is another side effect of Antipsychotic Drugs