L25 SAQ - Biogenic Amines and Neurotransmitters Quiz

Dopamine Transporter and Degradation

• The dopamine transporter is responsible for the reuptake of dopamine from the synapse, terminating the signal.
• Inhibition of the dopamine transporter can be achieved through cocaine and other psychostimulants.
• Dopamine degradation occurs through two mechanisms: enzymatic degradation and reuptake.
• Enzymatic degradation involves the breakdown of dopamine by two enzymes: monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT).

Monoamine Oxidase (MAO)

• MAO enzymes are located in the outer mitochondrial membrane and are responsible for the breakdown of dopamine.
• MAO has two forms: MAO-A and MAO-B, with different substrate specificities.

Catechol-O-Methyltransferase (COMT)

• COMT is responsible for the transfer of a methyl group to dopamine, inactivating it.
• COMT is found in the synaptic cleft and is involved in the degradation of dopamine.

Diseases Associated with Dopamine System

• Diseases associated with the dopamine system include Parkinson's disease, schizophrenia, and attention deficit hyperactivity disorder (ADHD).

Parkinson's Disease

• The main pathology in Parkinson's disease is the degeneration of dopamine-producing neurons in the substantia nigra, leading to motor symptoms.
• The neural projections involved in motor control are the cortico-striatal-thalamo-cortical circuit and the basal ganglia.

Treatments for Parkinson's Disease

• The sites of action of common treatments for Parkinson's disease include the dopamine transporter, dopamine receptors, and monoamine oxidase (MAO) inhibitors.

Biogenic Amines and Catecholamines

• Biogenic amines are a class of neurotransmitters that include dopamine, norepinephrine, and serotonin.
• Catecholamines are a subclass of biogenic amines that include dopamine, norepinephrine, and epinephrine, characterized by a catechol group.
• Dopamine is a catecholamine neurotransmitter.

Biosynthetic Pathway for Catecholamines

• The biosynthetic pathway for catecholamines involves the conversion of tyrosine to L-dopa by tyrosine hydroxylase.
• L-dopa is then converted to dopamine by aromatic L-amino acid decarboxylase.

Tyrosine Hydroxylase

• Tyrosine hydroxylase is the rate-limiting enzyme in the biosynthetic pathway of catecholamines.

Norepinephrine and Epinephrine

• Norepinephrine and epinephrine are catecholamine neurotransmitters involved in the sympathetic nervous system.

Vesicular Transport and Storage

• The vesicular monoamine transporter (VMAT) mediates the uptake of dopamine into vesicles for storage.

Dopamine β-Hydroxylase (DBH)

• Dopamine β-hydroxylase (DBH) is an enzyme involved in the conversion of dopamine to norepinephrine in vesicles.

Dopamine Receptors

• The main types of dopamine receptors are D1-like receptors and D2-like receptors.
• D1-like receptors are involved in the activation of adenylyl cyclase, increasing cAMP levels.
• D2-like receptors are involved in the inhibition of adenylyl cyclase, decreasing cAMP levels.

Test your knowledge on biogenic amines, bioactive amine neurotransmitters implicated in various behaviors such as movement, reward, addiction, depression, and sleep. Learn about the catecholamines and their role as neurotransmitters like dopamine and norepinephrine. Explore the pharmacological drugs that affect their neurotransmission.