Inverse Agonism and Functional Selectivity

Inverse Agonism and Functional Selectivity

Agonist-Antagonist

The use of psychopharmacological agents is to help correct a suspected imbalance of chemicals within our brain, and to do this the medications either enhance, suppress, or help transport with the help of signals and receptors. To help achieve these processes, the medications produce either an agonist or antagonist to achieve the desired response. An agonist action locates target receptors and bind and alter the activity at the receptor to achieve the desired response from the receptor, using affinity and intrinsic efficacy properties (either full or partial) (Berg & Clark, 2018). An Antagonist action does not have any intrinsic efficacy but does have affinity and may not produce a response but will till bind to the target receptor and thus will reduce the available presence and response for target binding of an agonist (Berg & Clark, 2018). Inverse Agonism and Functional Selectivity  By increasing the occupancy at the receptor with additional agonist, it would cause a blocking effect of the antagonist (Berg & Clark, 2018). For referral of maximal response would be a full agonist (which does not always require maximum number of receptors to provide achieved response) and a partial agonist does just that, provide a partial response with the use of all required receptors, if the intrinsic efficacy is greater is another agonist, it will require less occupancy of receptors (Berg & Clark, 2018). Inverse agonist binds to target receptors and provide negative intrinsic efficacy which decreases the activity at that receptor and can vary from either partial (which are weak) or strong agonists (responses) (Berg & Clark, 2018). Competition can exist between different agonists at target receptor sites and can only hold one ligand at each receptor. Inverse Agonism and Functional Selectivity

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G Protein Couple and Ion Gated Channels

Neurotransmitter receptors have two responses, rapid and slow. The rapid response is facilitated with the use of ion gated channels and happens within milliseconds and is referred to as an ionotropic receptor (Berk, Lodish, & Zipursky, 2000). Ion gated channels are responsible for the electrical excitation of neurons by facilitating the conversion of ion flux from chemical signals to across the membrane that are responsible for memory and attention (Li, Liu, & Wong, 2014). Ion gated channel allow specific ions to pass through the membrane to bind a ligand (Li, Liu, & Wong, 2014). The slow post synaptic response is facilitated with the use of G protein couple receptors that indirectly monitor the opening and closing of ion channels which occur at slower rates over seconds to minutes and is considered a metabotropic receptor (Berk, Lodish, & Zipursky, 2000). G coupled proteins are responsible for the psychological responses to hormones as well as neurotransmitters (Kobilka, Rassmussen, & Rosenbaum, 2014). Interactions between g protein coupled receptors and ion gated channels involve different dopamine receptors including D5-GABAa, D1-NMDA, and D2-AMPA (Li, Liu, & Wong, 2014). G protein coupled receptors bind ligand and activates the membrane protein that interacts with ion channel (Li, Liu, & Wong, 2014). Inverse Agonism and Functional Selectivity

Epigenetics

Epigenetics refers to the change that can be made to alter gene expression activity without making any changes to the sequencing of DNA by outside factors, and has been found to be passed on to future generations (Weinhold, 2006). Epigenetics can be done with a few processes, one of them being methylation which will delete one of the two alleles present on a gene (Weinhold, 2006). Although it may seem that this could be helpful in ridding of certain conditions, it has been found that it can also predispose the affected population with other medical and mental health concerns (Weinhold, 2006). Changes to genes may be caused by different factors, including chemical and environmental. One study by Michael Skinner at the University of Washington exposed pregnant rats to high levels of methoxychlor (insecticide) and fungicide vinclozolin and found that in male pups born from the affected mothers, they showed that for the next four generations there was decreased sperm production and infertility due to the exposure of chemicals and changes to gene expression (Weinhold, 2006). Inverse Agonism and Functional Selectivity

Medication Prescription Awareness

It is important for a prescriber to be aware of the short-term and long-term goals of medication prescribing to patients. One thing to consider is the effects within the body, and how that certain medication is going to be beneficial or possibly harmful in the present or future. Opioids are a good example of a medication that can have good effects, with increased tolerance, and possibly detrimental consequences. Many patients with pain management issues end up having to take an opioid for pain relief, however, tolerance to opioids can happen quickly, and this unfortunately will lead to addiction however that is not the primary concern. A primary concern with prescribing opioids and the increased tolerance quickly achieved, the resort would be to increase the pain medication to achieve pain relief. This however can lead to consequential effects such as respiratory depression, coma, and possibly even death (Christie & Morgan, 2011). Over prescribing, or adding an additional opioid or other type of medication such as a benzodiazepine could increase the risk for injury therefore the prescriber must ensure that medications being prescribed will not do harm versus good. Inverse Agonism and Functional Selectivity

References:

Berg, K. A., & Clarke, W. P. (2018). Making sense of pharmacology: Inverse agonism and functional selectivity. International Journal of Neuropsychopharmacology, 21(10), 962-977. doi:10.1093/ijnp/pyy071

Berk, A., Lodish, H., & Zipursky, S. (2000). Molecular Cell Biology 4th edition. ., .: W H Freeman &.

Kobilka, B. K., Rasmussen, S. G., & Rosenbaum, D. M. (2009, May 21). The structure and function of g-protein-coupled receptors. Retrieved March 11, 2021, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3967846/

Li, S., Liu, F., & Wong, A. H. (2014, May 9). Ligand-gated ion channel interacting proteins and their role in neuroprotection. Retrieved March 11, 2021, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4023026/

Weinhold, B. (2006, March). Epigenetics: The science of change. Retrieved March 11, 2021, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1392256/ Inverse Agonism and Functional Selectivity