User:Bilalabualrub/Agonist-antagonist

 Agonist-antagonist draft 

Background

An agonist is a compound that increases the effect of a neurotransmitter by increasing the amount of time the neurotransmitter is in the synaptic cleft acting upon receptors of the post synaptic dendrite. An antagonist is a compound that has the opposite effect of an agonist. It decreases the effect of a neurotransmitter by decreasing the amount of time the neurotransmitter is in the synaptic cleft. These actions can be achieved via multiple mechanisms. A common mechanism for agonists is re-uptake inhibition, meaning that the agonist blocks neurotransmitters from reentering the pre-synaptic axon terminal. This gives the neurotransmitter more time in the synaptic cleft to act on the synaptic receptors. Conversely, antagonists often bind directly to receptors in the synaptic cleft, effectively blocking neurotransmitters from binding.

One of the essential reasons Agonist-antagonists are safer to use than full opioid agonists is because they have a ceiling effect on respiratory depression. This is the cause of mortality in opioid overdoses, so this limits risk of abuse for recovering opioid addicts. [1]

Examples

Buprenorphine is an example of an agonist-antagonist. It is a partial agonist meaning, it activates opioid receptors, but to a much lesser degree than a full agonist, like morphine or fentanyl. It acts as an antagonist by blocking other opioids from binding, while still partially activating the mu opioid receptor. [1] The mu opioid receptor s are a class of opioid receptors that have a high affinity for enkephalins and beta-endorphin.Thus, this specific compound illustrates one importance aspect of agonist-antagonists; They can be used to treat opioid addiction.

Sources


 * 1) Kumar, Rachna. “Buprenorphine.” StatPearls [Internet]., U.S. National Library of Medicine, 12 Feb. 2019, https://www.ncbi.nlm.nih.gov/books/NBK459126/.

Corrections

-Change sigma to sigma 1 throughout, outdated info

-Title could be considered misleading and the opioid examples don't necessarily change action, consider changing?