NURS 6630 UMES Wk 2 Foundational Neuroscience Psych Treatment Discussion

Week 2 Discussion Main Post

Agonist-to-Antagonist

When a drug works as an agonist, it binds to the receptors and copies the body’s molecules (Rosenthal & Burchum, 2020). This increases the effects of the neurotransmitter on the postsynaptic neuron of a cell (Rosenthal & Burchum, 2020). Lorazepam, a benzodiazepine, acts as an agonist at the specific receptor and assists the gamma-aminobutyric acid (GABA) (Kowalski et al., 2017). An antagonist is a drug with an affinity for a particular receptor site but does not have intrinsic activity (Rosenthal & Burchum, 2020). Antagonists have no effect by themselves on receptor function. However, just because they do not cause activation, they still produce pharmacologic effects. Antagonists cause effects by preventing the activation of the receptors (Rosenthal & Burchum, 2020). Keep in mind, the response to an antagonist is determined by the amount of the agonist present. Flumazenil is a benzodiazepine antagonist(Kowalski et al., 2017). Nothing happens unless a benzodiazepine is present. When a benzodiazepine is present, flumazenil reverses the activity and returns the cell’s ion channel to its resting state and why it is used in benzodiazepine overdose (Kowalski et al., 2017). Agonists can also be partial agonists which only have moderate intrinsic activity. This results in the maximum effect of a partial agonist are less than that of a full agonist, as one would expect (Rosenthal & Burchum, 2020). Partial agonists can sometimes act as antagonists and are sometimes referred to as agonist-antagonists(Rosenthal & Burchum, 2020). Buspirone is a partial agonist on serotonin 1a receptors (Kowalski et al., 2017). An inverse agonist has the opposite effect of an agonist and depends on the receptor continuing to fire in the absence of an agonist (Kowalski et al., 2017). Kowalski et al. (2017) state that if an agonist opens a channel, an inverse agonist will close it. Naloxone is an example of an inverse agonist (Kowalski et al., 2017).

G Coupled Proteins and Ion Gated Channels

G-protein coupled receptors (GPCR) are the largest class of membrane protein receptors. GCPRs share a common architecture and sense molecules outside the cell and activate signal transduction inside the cell, which produced a cellular response (Alexander et al., 2019). They are made up of receptors for hormones such as calcitonin and neurotransmitters like serotonin and dopamine (Alexander et al., 2019). They are the frequent target of medication. Ion gated channels regulate cellular excitability (McCance & Huether, 2019). They contain calcium, sodium, and potassium channels, which open and close depending on the action of the neurotransmitter, drug, or hormone (McCance & Huether, 2019).

Both GPCRs and ion gated channels are present in the plasma membrane and are essential in intracellular signaling. The most significant difference between the two is the amount of time it takes to produce the action onset (Stahl, 2013). Ion channel medications cause the ion to attach to the receptor triggering the ions’ movement, causing an immediate reaction to the drug (Stahl, 2013). GCPR medications cause a chemical to bind to the receptor triggering changes altering which genes are expressed and which proteins are created (Stahl, 2013). This type of response occurs over time and have a more prolonged onset of action (Stahl, 2013).

Epigenetics

While epigenetics has various meanings, the overall idea is that gene function can be changed by an individual’s behavior and environment (CDC, 2020). Unlike genetic changes, epigenetic changes are reversible and do not affect the DNA sequence directly. However, they can change how your body reads a sequence of DNA (CDC, 2020). Genetic changes alter how a protein is made, epigenetics change on/off switch of the way genes are expressed. Medications are one-way switch gets flipped or not (CDC, 2020). Changes caused by medications do not affect the receptor alone but can cause a widespread response to regulate the genes (CDC, 2020).

Impact

As healthcare providers, it is crucial to understand how a medication will affect the patient. There are many medications prescribed to treat psychiatric disorders—however, only a few sites of action where a drug triggers a reaction in the brain. The advanced practice nurse must have a strong knowledge of neuroscience, which will provide a clearer understanding of psychiatric disorders, the medication used to treat the disease, and the expected clinical outcomes.

References

Alexander, S. H., Christopoulos, A., Davenport, A. P., Kelly, E., Mathie, A., Peters, J. A., Veale, E. L., Armstrong, J. F., Faccenda, E., Harding, S. D., Pawson, A. J., Sharman, J. L., Southan, C., Davies, J. A., Abbracchio, M. P., Alexander, W., Al-hosaini, K., Bäck, M., Beaulieu, J.,…Yao, C. (2019). The concise guide to pharmacology 2019/20: G protein‐coupled receptors. British Journal of Pharmacology, 176(S1). Retrieved December 6, 2020, from https://doi.org/10.1111/bph.14748

CDC. (2020, December 7). What is epigenetics? cdc.gov. Retrieved December 7, 2020, from https://www.cdc.gov/genomics/disease/epigenetics.htm

Deichmann, U. (2016). Epigenetics: The origins and evolution of a fashionable topic. Developmental Biology, 416(1), 249–254. Retrieved December 7, 2020, from https://doi.org/10.1016/j.ydbio.2016.06.005

Kowalski, P. C., Dowben, J. S., & Keltner, N. L. (2017). My dad can beat your dad: Agonists, antagonists, partial agonists, and inverse agonists. Perspectives in Psychiatric Care, 53(2), 76–79. https://doi.org/10.1111/ppc.12208

Rosenthal, L. D., & Burchum, J. (2020). Lehne’s pharmacotherapeutics for advanced practice nurses and physician assistants (2nd ed.). Saunders.

Stahl, S. M. (2013). Stahl’s essential’s psychopharmacology: Neuroscientific basis and practical applications (4th ed.). Cambridge University Press.

Stern, T. A., Fava, M., Wilens, T. E., & Rosenbaum, J. F. (2016). Massachusetts general hospital: Psychopharmacology and neurotherapeutics (1st ed.). Elsevier.

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