NURS – 6630 Discussion: Foundational Neuroscience
Agonist-to-Antagonist Spectrum of Action
According to Indian Health Service (IHS, 2020), an agonist is any drug that activates specific brain receptors, thus causing the full effect of the drug to take place (p. 1). A partial agonist is a drug that acts as an agonist but the degree of receptor activation is reduced. When a drug is classified as an antagonist, it means that the drug blocks the receptors so they are not able to bind to the agonist. In the realm of opioids, an example of an agonist is Heroin, the antagonist is Naloxone, and a partial agonist is Buprenorphine. To expand on this example, Heroin is an addictive agonistic substance. In the case of a Heroin overdose, Naloxone, an antagonist, can be used to reverse the binding and block receptors from binding with free-floating Heroin. Pharmacological treatment for Heroin addiction often includes the partial agonist, Buprenorphine. Buprenorphine allows partial binding to opioid receptors, thus reducing withdrawal symptoms and curving drug cravings (IHS, 2020, p. 2).
Compare and Contrast: Ion Gated Channels and G-couple-proteins
Ion Gated Channels (IGCs) and G-protein-coupled receptors (GPCRs) are two classes of postsynaptic receptors. IGCs, also referred to as ligand-gated ion channels, have two domains. One domain functions to bind neurotransmitters (extracellular) and the other that forms the ion channel. GPCRs work via second messenger systems that are slower and rely on a variety of metabolic steps (Camprodon & Roffman, 2016, p. 47). GPCRs are also called metabotropic receptors. When the neurotransmitter binds to the metabotropic receptors, the G-proteins are activated. The G-proteins then separate from the receptor and directly interact with the ion channels or pair with effector proteins to control the ion channels via intracellular messengers (McEnery & Siegel, 2014, p. 552).
Epigenetics and Pharmacological Action
Epigenetics can be defined in many ways, but the basis is that gene function can be altered without changing the DNA and RNA code. This functional change in the gene can also be inherited (Camprodon & Roffman, 2016, p. 64). As a result, epigenetics can determine how a medication works and what illnesses an individual may develop. If a medication works on a specific gene, but that gene has an altered function, the drug’s efficacy may change. For example, individuals with altered dopamine formation and receptor binding may have an affinity towards drug addiction or a degree of natural tolerance (Saad et al., 2019, p. 1534). For non-addictive substances, this logic holds true as to why some medications work for one person, but not another individual.
Best Practice
It is essential to gather a thorough medical and family history before prescribing medications. Currently, the clinic I work in considers the patient’s familial medication history when prescribing medications, as well as genetic testing for patients where multiple psychotropics drugs have failed to treat their symptoms. As previously stated, some genes that affect medication efficacy may be inherited. In knowing what medications have worked for close relatives in the patient’s family, the patient may find success in using the same medication because of epigenetics.
Genetic Testing One of the reasons the genetic testing is performed is to assess if the patient has normal Methylenetetrahydrofolate reductase gene function and is able to convert Folate to L-Methyl-Folate (LMF). LMF is necessary for the production of serotonin, dopamine, and norepinephrine (Shelton, Manning, Barrentine, & Tipa, 2013, p. 2). If this is impaired, even with medication, the patient’s body is not appropriately producing enough of the LMF cofactor to produce the necessary neurotransmitters for a stable mood- hence drug-resistant depression. Medication prescribing is not “cookie-cutter.” Modern science gives prescribing providers greater insight into what is going on in the very foundation of their patient’s being, their DNA. Although some are skeptical of genetic testing for psychotropic medications, I have first-hand seen the benefits in my employer’s clinic by using this resource as a means of guided prescribing.
References
Camprodon, J. A., & Roffman, J. L. (2016). Psychiatric neuros
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