BIOL 3370 Chemical Synapses - Neurotransmitters

These flashcards cover key concepts related to neurotransmitters and their functions, synthesis, and types based on the provided lecture notes.

What are ionotropic receptors?

Ligand-gated ion channels that cause direct graded potentials.

What are metabotropic receptors?

G-protein coupled receptors that can have modulatory effects on neurotransmitter functions.

May affect:

• Opening of ion channels

• Synthesis, release, degradation, and/or reuptake of neurotransmitter

• Number of receptors at synapse

What is the rate-limiting step in the synthesis of acetylcholine?

Choline acetyltransferase (ChAT, CAT).

What enzyme removes acetylcholine from the synapse?

Acetylcholinesterase (AChE).

What neurotransmitter is characterized by a combination of acetic acid and choline?

Acetylcholine.

Name two types of receptors for acetylcholine.

Nicotinic (nACh) receptors -ionotropic

Muscarinic (M) receptors -metabotropic

What role does serotonin play in the body?

Digestion, appetite, sleep, social behavior, and mood.

Which precursor is used to synthesize catecholamines?

Tyrosine.

What is the role of dopamine in the brain?

Reward and reinforcement, motivation, and motor control.

What are the two types of adrenergic receptors?

Alpha (α) and beta (β) receptors.

What function does glutamate have in the brain?

Main excitatory neurotransmitter, involved in learning, memory, and attention.

What characterizes GABA as a neurotransmitter?

It is the main inhibitory neurotransmitter of the brain.

Which neurotransmitter is derived from tryptophan?

Serotonin.

What is the primary site of melatonin synthesis?

The pineal gland.

What is the effect of caffeine on adenosine receptors?

Caffeine inhibits adenosine receptors, increasing alertness.

What is a significant function of endocannabinoids?

They play a role in motor control, learning, memory, and mood.

Where are endocannabinoids produced?

By enzymatic degradation of membrane lipids.

What neurotransmitter is the simplest amino acid?

Glycine.

What is the rate-limiting enzyme in the synthesis of GABA?

Glutamic acid decarboxylase (GAD).

What neurotransmitter is primarily associated with the sympathetic response?

Epinephrine and norepinephrine.

What effect does norepinephrine have on cardiac muscle?

It's excitatory.

What effect does norepinephrine have on the smooth muscle of the respiratory tract?

It's inhibitory.

What neurotransmitter is involved in the body's arousal and wakefulness?

Histamine.

What are the transporters that remove dopamine from synapses?

Dopamine transporters (DAT), monoamine oxidase (MAO), and catechol O-methyltransferase (COMT).

What role does serotonin play in disorders like anxiety and depression?

Imbalances in serotonin levels are linked to these disorders.

What are the main roles of glycine?

Processing of motor and sensory information and acting as a co-agonist at NMDA receptors.

What is the function of ATP in neurotransmission?

It acts as a neurotransmitter as a nucleotide.

What are the removal mechanisms for neurotransmitters?

Transporters and enzymes such as monoamine oxidase.

What are the functions of endocannabinoids?

Regulate pain, appetite, and mood.

What neurotransmitter is associated with opioid peptides?

Endorphins and enkephalins.

Which neurotransmitter affects learning and memory and is primarily excitatory?

Glutamate.

Name a neurotransmitter that plays a role in sleep regulation.

Melatonin.

What effect does serotonin increase have?

It can lead to serotonin syndrome.

What role does GABA play in mood regulation?

It helps regulate brain activity and can affect mood.

What neurotransmitter is involved in pain regulation and mood?

Endocannabinoids.

What is the function of adenosine in the brain?

Acts as an inhibitory neurotransmitter promoting sleep.

What is the defining characteristic of imidazoleamines?

They are derived from the amino acid histidine.

What are glutamate receptors primarily responsible for?

Excitation of neurons.

How does the receptor type affect neurotransmitter response?

It determines if the neurotransmitter has excitatory or inhibitory effects.

What is the connection between dopamine and addiction?

Dopamine plays a role in reward pathways and can affect addiction behaviors.

What are the 3 Monoamines?

Catecholamines

Indolamines

Imidazoleamines

Describe the structure of Catecholamines and what are 3 examples

Catecholamines are characterized by a benzene ring with two hydroxyl groups and an ethyl side chain that connects to an amino group. Three examples include dopamine, norepinephrine, and epinephrine.

What is the rate-limiting step in synthesis for catecholamines

Tyrosine hydroxylase (TH)

What’s the removal mechanism for catecholamines

Transporters

Monoamine oxidase (MOA)

Catechol O-methyltransferase (COMT)

-these are all enzymes that are important in the metabolism of catecholamines and help regulate their levels in the synaptic cleft.

What is the removal mechanism for acetylcholine

Acetylcholinesterase (AChE)

What are the functions of Acetylcholine?

Skeletal muscle response

Autonomic response-especially parasympathetic

Memory

What is the receptor/s for catecholamines?

Dopamine (D)

In Catecholamines what is the function of Dopamine and what disease does it play a role in?

Reward & reinforcement

Motivation

Extrapyramidal motor control- which helps modulate movement rather than initiate it

It has a role in Parkinson's disease, schizophrenia, bipolar disease, etc.

In Catecholamines, Epinephrine & norepinephrine receptors are…?

Adrenergic (alpha and beta) receptors- these are metabotropic

In Catecholamines, what are Epinephrine & norepinephrine functions?

Sympathetic response- fight or flight response, can increase heartrate

Arousal & attention

Has some effects on mood

Plays role in ADHD and anxiety

Classified as an Indolamine, ___________ is derived from decarboxylated trpptophan with an added hydroxyl group

Serotonin

The ______ gland is the primary site of melatonin synthesis

pineal gland

Tryptophan is first converted to serotonin then acetylated and methylated to produce _________.

Melatonin

Classified as an Indolamine, what are the Serotonin receptors?

5-HT3 receptors – ionotropic

5-HT1,2,4,5,6 receptors - metabotropic

Classified as an Indolamine, what is the rate-limiting step in the synthesis of serotonin?

Tryptophan hydroxylase (TPH)

Classified as an Indolamine, what is the removal mechanism for Serotonin?

Transporters

Monoamine oxidase (MOA)

Classified as an Indolamine, what is the function of serotonin?

Digestion, appetite, sleep, social behavior, and mood

• Plays a role in depression, anxiety disorders, sleep disorders

Drugs that increase levels of serotonin (e.g., SSRI) can cause __________ _________

Serotonin Syndrome

• causes confusion, rapid heart rate, high blood pressure, sweating, tremors, muscle rigidity, and seizures

Classified as an Indolamine, what are the Melatonin receptors?

MT receptors - metabotropic

Classified as an Indolamine, what is the rate-limiting step in the synthesis of melatonin?

Arylalkylamine N-acetyltransferase (AANAT)

Classified as an Indolamine, what is the removal mechanism for melatonin?

Unclear but its dispersed and broken down by the liver, acts similar to hormones

Classified as an Indolamine, what is the function of Melatonin?

Plays a role in circadian rhythms

Classified as an Imidazoleamine, ____________ is characterized by a single amino group connected to an imidazole ring by a ethyl chain

Histamine

What is this molecule?

Histamine

Classified as an Imidazoleamine, what are the histamine receptors?

H receptors- metabotropic

Classified as an Imidazoleamine, what is the rate-limiting step in the synthesis of histamine?

Histamine decarboxylase (HDC)

Classified as an Imidazoleamine, what are the removal mechanisms of histamine?

Transporters (haven’t yet narrowed them all down)

Classified as an Imidazoleamine, what is the function of histamine

Wakefulness

Inflammatory response

____________ is thought to be the most important for brain function, and is the main excitatory neurotransmitter in the central nervous system.

Glutamate

What amino acid is this image?

Glutamate

Classified as an amino acid, what are the glutamate receptors? (4 of them)

AMPA receptors- ionotropic

NMDA receptors-ionotropic

Kainate receptors- ionotropic

mGlu receptors- metabotropic

Classified as an amino acid, what is the rate-limiting step in synthesis of glutamate?

Glutaminase

Classified as an amino acid, what is the removal mechanism of glutamate?

Transporters (EAATs)

_______ metabolism can also be used to synthesize glutamate?

Glucose

Classified as an amino acid, what are the functions of glutamate?

Learning, memory, attention, mood regulation, and movement

• Imbalances play a role in anxiety, ADHD, seizures, and neurodegenerative diseases

________ is a main inhibitory neurotransmitter of the brain.

GABA (γ-aminobutyric acid)

Classified as an Amino Acid, what are the GABA receptors?

• GABA_A receptors – ionotropic

• GABA_B receptors – metabotropic

Classified as an Amino Acid, what is the rate-limiting step in synthesis of GABA?

Glutamic acid decarboxylase (GAD)

Classified as an Amino Acid, what is the removal mechanism for GABA?

Transporters (GATs)

Classified as an Amino Acid, what are the functions of GABA?

Regulation of brain activity, sleep, motor control, mood

Presynaptic inhibition of glutamatergic neurons

_______ is the main inhibitory neurotransmitter of the spinal cord

Glycine

What amino acid is the image?

Glycine

Classified as an Amino Acid, what are the glycine receptors?

Glycine receptors- ionotropic

Classified as an Amino Acid, what is the rate-limiting step in synthesis of glycine?

Phosphoserine phosphatase (PSP)

Classified as an Amino Acids, what is the removal mechanism of glycine?

Glycine transporters

Classified as an Amino Acids, what is the function of glycine?

Processing of motor and sensory information coming and going to the peripheral nervous system

• Interestingly, it also plays a role in excitatory neurotransmission as it is a co-agonist at NMDA receptors

• Plays a role in synaptic plasticity, learning, and memory

____________ is a purine nucleoside composed of adenine attached to ribose

Adenosine

Adenosine (A) receptors are _________

metabotropic

_________acts as an inhibitory neuron in the brain promoting sleep and suppressing arousal

Adenosine

__________inhibits adenosine receptors increasing alertness

Caffeine

Identify the amino acid

Adenosine

_______________ are small, lipid-derived molecules that are produced by enzymatic degradation of membrane lipids

Endocannabinoids

What are 2 examples of endocannabinoids?

• Anandamide (AEA)

• 2-arachidonoyglycerol (2-AG)

________________ are not stored in vesicles, production is stimulated by activation of G-protein-coupled receptors

Endocannabinoids

Endocannabinoids bind to ____________ receptors

cannabinoid

What are the 2 receptors of endocannabinoids? What role do they play? What are they responsible for?

• CB1 receptors – play a role in motor control, learning, memory, pain, appetite, mood

• Responsible for the psychoactive effects of cannabis

• CB2 receptors – regulate inflammation and pain

• mostly found in the spinal cord