Lecture 5 - Receptor Pharmacology Flashcards
Question: What is an agonist?
Answer: An agonist is a substance, whether it be a drug or a naturally occurring body substance, that directly causes a measurable response when it binds to a receptor. This response can be either excitatory or inhibitory.
Question: Define affinity in the context of receptor binding.
Answer: Affinity refers to the binding strength or attraction between an agonist (or any drug) and its receptor. It determines how likely the agonist is to bind to the receptor.
Question: What is efficacy regarding agonists?
Answer: Efficacy refers to the ability of an agonist (or any drug) to activate the receptor once it is bound, leading to the elicitation of a response. In other words, efficacy determines how well the agonist can produce the desired effect upon binding to the receptor.
Question: What does agonist quantification allow for?
Answer: Agonist quantification enables the comparison of EC50 values, where the lower the value, the more potent the drug is considered to be.
What is an antagonist?
Answer: An antagonist is a substance, whether it be a drug or another chemical compound, that counteracts the actions of an agonist by binding to the same receptor type without eliciting a response.
Question: What is pharmacological antagonism?
Answer: Pharmacological antagonism occurs when drugs counteract each other by acting on the same receptor type.
Question: Describe the concept of affinity in the context of antagonists.
Answer: Affinity refers to the binding strength or attraction between an antagonist (or any drug) and its receptor. It determines how likely the antagonist is to bind to the receptor.
Question: What are the two types of antagonism?
Answer: The two types of antagonism are chemical antagonism, where one drug antagonizes the action of another by chemically combining with it, and physiological antagonism, where two drugs counteract each other by producing opposing effects on different receptors.
Question: How could you relate antagonism to neurotransmission?
Answer: Antagonism in neurotransmission occurs when a substance binds to a receptor without activating it, thereby inhibiting the actions of an agonist. This can result in the reduction or blocking of the normal physiological effects of neurotransmitters.
Question: What would a glutamate antagonist do to overall synaptic activity?
Answer: A glutamate antagonist would reduce overall synaptic activity by blocking the action of glutamate, the primary excitatory neurotransmitter in the central nervous system. This would lead to a decrease in excitatory signaling and potentially affect processes such as learning, memory, and neuronal excitability.
Question: What would a GABA antagonist do to overall synaptic activity?
Answer: A GABA antagonist would increase overall synaptic activity by blocking the action of gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the central nervous system. This would lead to a decrease in inhibitory signaling, resulting in heightened neuronal excitability and potentially causing seizures or other hyperexcitability-related phenomena.
Question: What is competitive antagonism?
Answer: Competitive antagonism occurs when a substance (the antagonist) competes with an agonist for binding to the same receptor site. Increasing the concentration of the agonist can restore the response because the antagonist can be displaced from the receptor by higher concentrations of the agonist.
Question: What are other types of antagonism besides competitive antagonism?
Answer:
1. Irreversible-competitive antagonism: In this type of antagonism, the bond between the antagonist and the receptor is so strong that even increasing concentrations of agonists cannot displace the antagonist. This is often due to covalent bonding.
2. Non-competitive antagonism: These antagonists act at sites other than the agonist binding site on the receptor.
Can antagonists and agonists have the same physiological effect?
Answer: Yes, antagonists and agonists can have the same physiological effect, depending on the location of the receptor they target. For example, if both an agonist and an antagonist bind to different receptors that ultimately lead to the same downstream effect, they can produce similar physiological outcomes despite their opposing mechanisms of action.
Give an example where this occurs.
Activation of the μ opioid receptor can inhibit pain signaling in the spinal cord. Both agonists and antagonists acting on this receptor can result in the inhibition of pain signaling, despite their different mechanisms of action.
