Dopamine in CNC Abdulelah Nuqali Intern

Overview Introduction Biochemistry Dopamine receptors Dopaminergic pathways Summary 2

Introduction Dopamine belongs to the family of catecholamines Hormones Epinephrine and Norepinephrine (other catecholamines) are derived from Dopamine Significant role in learning, goal-directed behavior, regulation of hormones, motor control 3

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Synthesis DOPA is converted so rapidly into Dopamine 5 Rate Limiting Step

Metabolism In primates and human – HVA major metabolite Accumulation of HVA in brain or CSF used as index of function of dopaminergic neurons 6

Dopamine Receptors D 1 – like family: – Includes subtypes D 1 and D 5 – Activation is coupled to G αs ; activates adenylyl cylcase which leads to increase in concentration of cAMP D 2 – like family: – Includes D 2, D 3 and D 4 – Activation is coupled to G αi ; inhibits adenylyl cyclase leading to decrease in concentration of cAMP 7

Dopamine Receptors 8

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Dopamine Receptors 11

Dopaminergic Neurons 12

Dopaminergic Pathways Mesolimbic Pathway Mesocortical Pathway Nigrostriatal Pathway Tuberoinfundibular Pathway Incertohypothalamic Pathway Medullary Periventricular Retinal Olfactory bulb 13

Dopaminergic Pathways 14 Moore et al. 1978

Significance of Dopaminergic Pathways Mesolimbic Pathway – Associated with pleasure, reward and goal directed behavior Mesocortical Pathway – Associated with motivational and emotional responses Nigrostriatal Pathway – Involved in coordination of movement (part of basal ganglia motor loop) 15

Summary Neurotransmitter that acts as a modulator 2 family of receptors for dopamine 3 main pathways of action 16

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