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Questions and Answers
What is the primary function of neurotransmitters in the CNS?
What is the primary function of neurotransmitters in the CNS?
How do neuromodulators differ from neurotransmitters?
How do neuromodulators differ from neurotransmitters?
Which of the following best describes neurohormones?
Which of the following best describes neurohormones?
What role do neurotrophic factors play in the CNS?
What role do neurotrophic factors play in the CNS?
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The classification of CNS drugs according to WHO ATC primarily bases itself on what criterion?
The classification of CNS drugs according to WHO ATC primarily bases itself on what criterion?
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Which receptor subtype is primarily responsible for fast inhibitory postsynaptic potentials (IPSPs)?
Which receptor subtype is primarily responsible for fast inhibitory postsynaptic potentials (IPSPs)?
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What is the primary inhibitory neurotransmitter in the central nervous system (CNS)?
What is the primary inhibitory neurotransmitter in the central nervous system (CNS)?
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Which of the following statements about acetylcholine receptors is true?
Which of the following statements about acetylcholine receptors is true?
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What is one key effect of activating GABAB receptors?
What is one key effect of activating GABAB receptors?
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Which of the following accurately describes a role of acetylcholine?
Which of the following accurately describes a role of acetylcholine?
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What type of neurotransmitter is glutamate classified as?
What type of neurotransmitter is glutamate classified as?
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Which group of metabotropic glutamate receptors is primarily located postsynaptically?
Which group of metabotropic glutamate receptors is primarily located postsynaptically?
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What is a primary role of glutamate in the central nervous system (CNS)?
What is a primary role of glutamate in the central nervous system (CNS)?
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Which of the following receptors does NMDA act upon?
Which of the following receptors does NMDA act upon?
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How do Group II and III metabotropic receptors affect synaptic transmission?
How do Group II and III metabotropic receptors affect synaptic transmission?
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Which neurotransmitter acts as the primary inhibitory neurotransmitter in the CNS?
Which neurotransmitter acts as the primary inhibitory neurotransmitter in the CNS?
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What consequence can result from excessive activation of glutamate receptors?
What consequence can result from excessive activation of glutamate receptors?
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What is the role of glycine concerning glutamate receptors?
What is the role of glycine concerning glutamate receptors?
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Which pathway is primarily involved in motor control?
Which pathway is primarily involved in motor control?
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Dopamine receptor activation leads to which of the following effects?
Dopamine receptor activation leads to which of the following effects?
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Which system does serotonin primarily influence in terms of behavioral responses?
Which system does serotonin primarily influence in terms of behavioral responses?
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What is the function of the mesolimbic pathway?
What is the function of the mesolimbic pathway?
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What role do dopamine antagonists play in the management of vomiting?
What role do dopamine antagonists play in the management of vomiting?
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Which medication class inhibits the reuptake of serotonin?
Which medication class inhibits the reuptake of serotonin?
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What is the most likely effect of the mesocortical pathway dysfunction?
What is the most likely effect of the mesocortical pathway dysfunction?
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What common characteristic do triptans share in their pharmacological action?
What common characteristic do triptans share in their pharmacological action?
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What is the primary function of Ca2+ in neurotransmitter release?
What is the primary function of Ca2+ in neurotransmitter release?
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Which of the following accurately describes unconventional neurotransmitters?
Which of the following accurately describes unconventional neurotransmitters?
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What is a necessary condition for a chemical to be classified as a neurotransmitter?
What is a necessary condition for a chemical to be classified as a neurotransmitter?
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Which type of neurotransmitter is synthesized and stored at the terminal for fast release?
Which type of neurotransmitter is synthesized and stored at the terminal for fast release?
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Which proteins are primarily involved in the fusion of synaptic vesicles with the cell membrane during neurotransmitter release?
Which proteins are primarily involved in the fusion of synaptic vesicles with the cell membrane during neurotransmitter release?
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What process is responsible for the termination of neurotransmitter action at the synaptic cleft?
What process is responsible for the termination of neurotransmitter action at the synaptic cleft?
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What distinguishes peptide neurotransmitters from small molecule transmitters?
What distinguishes peptide neurotransmitters from small molecule transmitters?
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How does nitric oxide differ from conventional neurotransmitters?
How does nitric oxide differ from conventional neurotransmitters?
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Stimulating 5-HT autoreceptors will primarily lead to which of the following effects?
Stimulating 5-HT autoreceptors will primarily lead to which of the following effects?
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What role does noradrenaline play in the central nervous system?
What role does noradrenaline play in the central nervous system?
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Which statement regarding endocannabinoids is true?
Which statement regarding endocannabinoids is true?
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Activation of CB1 receptors is linked to which of the following effects?
Activation of CB1 receptors is linked to which of the following effects?
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Which of the following neurotransmitters is primarily associated with CNS depression when imbalanced?
Which of the following neurotransmitters is primarily associated with CNS depression when imbalanced?
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What might result from excitatory neurotransmission being overly active?
What might result from excitatory neurotransmission being overly active?
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Which drug class primarily affects noradrenaline transmission in the CNS?
Which drug class primarily affects noradrenaline transmission in the CNS?
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The imbalance of which neurotransmitter is primarily associated with seizures and cognitive impairment?
The imbalance of which neurotransmitter is primarily associated with seizures and cognitive impairment?
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Study Notes
Introductory Neuropharmacology
- This presentation covers introductory neuropharmacology
- The presenter is Robert Peter Biney, PhD, from the School of Pharmacy and Pharmaceutical Sciences, University of Cape Coast, Ghana
- The CNS is the most complex system
- Drug effects are difficult to understand
- There's a complex relationship between individual cellular behavior and whole-organ behavior
Learning Objectives
- Describe specific events at the neuronal synapse, relating to synthesis, storage, and release of neurotransmitters
- Identify major neurotransmitter types and receptors
- Explain the importance of specific neurotransmitters in health and disease.
- Describe how neurochemical imbalances may lead to neurological disorders.
Neuropharmacology
- Drugs affect behavior by influencing cellular function and neural mechanisms in the nervous system
- CNS drugs cross the blood-brain barrier (BBB) to affect brain function
- CNS drugs can selectively modify CNS function, and may stimulate or depress the CNS
- Drugs can alter mood, perception, consciousness, and behavior
Goals of Neuropharmacology
- Develop drugs to correct pathophysiological changes in the abnormal CNS
- Develop/use drugs as probe compounds to elucidate and manipulate the normal CNS
Neuropharmacology – Issues and Challenges
- The CNS is a very complex system
- Understanding drug effects is difficult
- The observed relationship between individual cellular behavior and whole-organ behavior is not direct.
- CNS-active drugs may act at multiple sites with disparate and opposing effects
- Many CNS disorders involve multiple brain regions and pathways, making a single therapeutic agent difficult
Classification of CNS Drugs – WHO ATC 1976
- An indication-based classification of CNS drugs that is primarily neurologically focused.
- Subdivided by indication, like analgesics (pain), anesthetics (surgery), etc.
- Detailed structure of the classification with specific types and categories of drugs, for example, antidepressants (N06A) to Anti-dementia drugs (N06D) are given.
Classification of CNS Drugs
- A table showing classes (e.g., general anesthetic agents), definitions (what the drugs do), and examples (specific types of drugs)
- Includes specific examples like opiates, benzodiazepines, and anti-depressants
Neurochemical Messengers
- Neurotransmitters: Cause changes in postsynaptic cells (excitation via depolarization or inhibition via hyperpolarization). Examples include acetylcholine.
- Neuromodulators: Affect a large population of neurons through slow synaptic actions. They can enhance or inhibit the effects of classical neurotransmitters. Example: Histamine.
- Neurohormones: Neuroendocrine cells release hormones into the bloodstream, acting at distant sites. Example: Oxytocin
- Neurotrophic factors: Assist neurons in repair, derived from neurons, astrocytes, microglia, or immune cells. Brain-derived neurotrophic factor is an example.
Neurotransmitters
- Endogenous chemicals in the brain that enable signaling across synapses
- Carry and modulate signals between neurons or other cell types
- Act on various targets to produce biological functions
- Cause electrical changes in postsynaptic cells, which can be excitation via depolarization or inhibition via hyperpolarization
History
- Otto Loewi and the discovery of chemical signaling in the nervous system (vagus stuff)
- Nobel Prize for this work in 1936, along with Henry Dale.
Neurotransmitters (Conventional vs. unconventional)
- Conventional: Stored in vesicles, released upon calcium influx, acting by binding to receptors on the postsynaptic cell membrane.
- Unconventional: Not stored in vesicles, can carry messages from postsynaptic to presynaptic neuron (retrograde), crossing the cell membrane to directly act inside the cell. Examples include endocannabinoids and nitric oxide.
Identification as a neurotransmitter
- Location within the presynaptic terminal of the neuronal pathway of interest.
- Release (in response to neuronal activity) must be calcium-dependent.
- Synaptic mimicry: The chemical should produce a response that mimics the transmitter released during nerve stimulation; this response should be blocked by a selective antagonist.
- Exceptions such as nitric oxide; not stored, synthesized on need, and diffuses across the membrane.
Synthesis and Storage
- Two main categories of neurotransmitters:
- Small molecule transmitters: Synthesized and stored in the terminal–fast release
- Neuropeptides: Synthesized in the cell body transported to the terminal-slower release.
- A neuron typically synthesizes and releases only one type of small molecule, while releasing multiple neuropeptides
Release
- Translocation/mobilization: Calcium influx phosphorylates synapsin, promoting translocation.
- Fusion and release: SNARE proteins guide and promote fusion with the cell membrane. Synaptobrevin, SNAP-25, Syntaxin, and Synaptotagmin.
- Target for neurotoxins.
Neurotransmitter Actions
- Ionotropic receptors: Ligand-gated channels
- Metabotropic receptors: G-protein coupled receptors (GPCRs)
Neurotransmitter Clearance
- Necessary for appropriate neural signalling, achieved through:
- Neuronal transport
- Degradation by enzymes
Learning Objectives (revisited)
- Appreciate how neurochemical imbalance leads to neurological disorders
Small Molecule Neurotransmitters
- Two classes: Amino Acids (e.g., glutamate, GABA, glycine, acetylcholine.)
- Biogenic Amines (e.g., dopamine, noradrenaline, serotonin, histamine)
Glutamate
- Primary excitatory neurotransmitter in the CNS
- Excitatory synaptic transmission is mediated by glutamate binding to ionotropic receptors.
Glutamate
- Acts on 3 ionotropic receptors subtypes (AMPA, Kainate, NMDA).
- Also acts on 8 metabotropic receptor subtypes.
- Effects may be excitatory or inhibitory.
AMPA and NMDA Receptors
- Synaptic plasticity
- Excitotoxicity
Glutamate (metabotropic receptors)
- 8 metabotropic receptors (mGlu1-8)
- Regulate cell excitability and synaptic transmission
- Group I—typically located postsynaptically, is largely excitatory
- Group II and III—typically located presynaptically, tend to reduce synaptic transmission and neuronal excitability
GABA
- Primary inhibitory neurotransmitter in the CNS
- Release from local interneurons
- Ubiquitous
GABA Receptor
- Ionotropic receptors (GABAA) : Gates Cl–, fast IPSP, and are blocked by picrotoxin and bicuculline, these are convulsants
- Metabotropic receptors
- Localized to perisynaptic regions
- Inhibits Ca2+ channels
- Also inhibits adenylyl cyclase
- Selectively inhibited by baclofen and is a spasmolytic
Acetylcholine
- First compound identified pharmacologically as a transmitter in the CNS
- Primary role in autonomic nervous system
- Important neurotransmitter at neuromuscular junction
- Important in memory
- Degeneration of cholinergic pathways is a hallmark of Alzheimer's disease
- Acts on two receptor subtypes: Nicotinic (ionotropic), and Muscarinic (metabotropic)
Dopamine
- Generally exerts a slow inhibitory action
- Four main dopaminergic pathways: Nigrostriatal, Mesolimbic, Mesocortical, and Tuberoinfundibular.
- Acts on 5 receptor subtypes (all metabotropic)
Serotonin
- 5-HT is involved in neurological responses, including behavioral responses, feeding behavior, mood, sleep, and vomiting
- Antidepressants (SSRIs, triptans) affect serotonin transmission
Noradrenaline
- Noradrenaline transmission is critical to the arousal system and control of mood
- Involved in functional deficiency contributing to depression
- Key psychotropic and antihypertensive drugs
Cannabinoids
- Endocannabinoids act as retrograde synaptic messengers
- Synthesized and secreted in response to intracellular Ca²⁺ increase
- Two receptor types (CB₁ and CB₂), linked to G-protein and inhibition of adenylate cyclase activity
- CB₁ primarily in CNS; CB₂ primarily in periphery
- Therapeutic potential for vomiting, pain, muscle spasms, and multiple sclerosis.
One minute papers
- Several different one minute papers appear to be presented covering various topics within neuropharmacology.
Note that some slides are visually engaging, but lack direct, substantive information; this summary is highly condensed and assumes essential details and relationships are easily understood from the illustrations and organization.
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Description
Test your knowledge on neurotransmitters, neuromodulators, and neurohormones in the central nervous system (CNS). This quiz covers their functions, classifications, and the specific roles they play in neurophysiology. Challenge yourself with questions on receptor subtypes, inhibitory neurotransmitters, and acetylcholine.
