NURS 6630 Foundational Neuroscience
NURS 6630 Foundational Neuroscience
NURS 6630 Foundational Neuroscience
Pharmacological agents produce both agonist and antagonist actions in different receptors in the human body. The agonist and antagonist actions of pharmacological agents work against one another. The agonists combine with the receptor to produce an action in the body. On the other hand, antagonist action hinders or opposes the action by a receptor, thereby, leading to a failure of an occurrence of an event. The effect of agonists is attributed to the combination it has with compounds or chemical substances to promote the desired action while that of antagonist entails the combination with chemicals or blockage of neurotransmitters to cause interference with action. Partial and inverse agonists have an effect on the efficacy of psychopharmacological agents. Partial agonists bind to a specific receptor to produce partial efficacy at that receptor that is relative to the effect of full agonist. The partial enhancement of the actions of the receptor results in a net decline in the activation of the receptor hence, average activity of the receptor in producing the desired action. Inverse agonists work by binding to a receptor as an antagonist to produce an action that is opposite to that of the agonist (Demler, 2019). Inverse agonists mimic the agonist activity of the receptors, hence, the desired therapeutic activity of psychopharmacological agents.
G-couple proteins and ion-gated channels are the mechanisms in which cells communicate to produce actions. They comprise of the cell-surface receptors that play the roles of signal transfer in multicellular organisms. The two however differ in a number of aspects. Ion-gated channels have receptors that bind to a ligand to cause opening of channels via membranes to allow the passage of specific ions. Ion-gated channels do not allow the passage of fatty acids and amino acids because they are hydrophobic in nature. Ion-gated channels therefore mediate rapid, post-synaptic responses. G-proteins channels on the other hand have receptors that bind and active G-protein on cell membranes. The activation of G-proteins results in cyclic series that cause entry of proteins such as amino acids and fatty acids into the cell to produce action (Hood & Khan, 2020). The G-proteins therefore mediate slow post-synaptic responses.
Epigenetics has a role in pharmacologic actions of drugs. Firstly, changes in the expression of enzymes that metabolize drugs may affect the action as well as metabolism of a drug. For example, changes in enzymes due to aspects such as DNA methylation affects the metabolism of drugs, leading to their altered effectiveness. The addition of methyl group to the cytosine pyrimidine ring causes silencing of transcription, thereby, hindering the binding of co-activators and transcription factors that are needed for metabolism and action of drugs. The second influence of epigenetics is the genetic variations in the transporters of drugs. A genetic change in the transporters of drugs such as ATP binding cassette transporters and solute carrier transporter affect the binding and action of pharmacological agents (Castelo-Branco & Jeronimo, 2020).
The above information will affect my prescribing of medications to patients. For instance, it will translate into my understanding of the disease process and the targets of the medications that I prescribe to the patients. The implication of the information also entails the need for comprehensive patient assessment to identify any relevant patient history that may affect the effectiveness of the prescribed medications. I should also be aware of the contraindications of specific medications to patients with history of allergies or comorbid conditions (Hood & Khan, 2020). Therefore, the information will inform my safe prescribing in my professional role as an advanced practice nurse.
References
Castelo-Branco, P., & Jeronimo, C. (2020). Histone Modifications in Therapy. Elsevier Science.
Demler, T. L. (2019). Pharmacotherapeutics for Advanced Nursing Practice, Revised Edition. Jones & Bartlett Learning.
Hood, P., & Khan, E. (2020). Understanding Pharmacology in Nursing Practice. Springer Nature.
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In pharmacodynamics, the main considerations are medication effects and mechanisms in the body. Therefore, for any medication to interact with the body, these drugs must get to their target cell to bind with a receptor. According to Rollema and Hurst (2018), receptors refer to specialized proteins within cells that bind to a ligand, a signal molecule, where they can easily alter their activity or shape. Such changes are crucial since they lead to cell behaviors and activity changes. Hence, depending on the drug’s effect on the receptor, these drugs usually exist in two categories, the antagonist and the agonists.
As the discussion post explains, agonists refer to drugs or medications that usually mimic signal ligand actions in terms where it binds and activates the receptor. For the antagonist, it refers to the medications that can easily bind to receptors with no activation. Still, in return, they decrease the receptor’s ability to be activated by an agonist. Within the classification, there are still medications under the partial agonists, which tend to resemble an agonist, but the difference is that its receptor activation is minimized. Hence, the maximal response associated with an agonist can be determined by receptors’ intrinsic activity or receptors’ numbers linked with the agonist, which mainly depends on provided agonist amount (Coleman et al., 2019).
In elaborating on the reactions between an agonist, antagonist, and partial agonist, these reactions happen mostly in individuals who use opioids. For instance, a drug like methadone is an agonist; it binds to receptors and becomes addictive. On the other hand, Naloxone presents itself as an antagonist, while an example of a partial agonist is the Buprenorphine. Therefore, if a patient has had a methadone overdose the clinician can opt for an antagonist like Naloxone to reverse binding and block any chance of methadone binding with the receptors (Mégarbane et al., 2020).
References
Coleman, R. A., Woodrooffe, A. J., Clark, K. L., Toris, C. B., Fan, S., Wang, J. W., & Woodward, D. F. (2019). The affinity, intrinsic activity and selectivity of a structurally novel EP2 receptor agonist at human prostanoid receptors. British journal of pharmacology, 176(5), 687-698. https://doi.org/10.1111/bph.14525
Mégarbane, B., Chevillard, L., & Vodovar, D. (2020). Naloxone should remain the appropriate antidote to treat opioid overdose. Critical Care, 24(1), 1-3. https://doi.org/10.1186/s13054-020-2835-5
Rollema, H., & Hurst, R. S. (2018). The contribution of agonist and antagonist activities of α4β2* nAChR ligands to smoking cessation efficacy: a quantitative analysis of literature data. Psychopharmacology, 235(9), 2479-2505. https://doi.org/10.1007/s00213-018-4921-9
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The agonist/antagonist spectrum represents how drugs can act on specific receptors. In psychophamacotherapy, G-protein-linked receptors are often targeted by medications using this spectrum (Stahl et al., 2021). On one side, you have an agonist. It is meant to fully activate a specific receptor (Stahl et al., 2021). Without an agonist, you still have the potential for particular receptors to be acted on naturally, but more weakly; this is called constitutive activity (Stahl et al., 2021). Agonists, as stated previously, can fully activate a receptor. They can do this both directly, by binding to a neurotransmitter site, or indirectly, by blocking both inactivation processes and eliminating neurotransmitters (Stahl et al., 2021). In sort of the middle of the spectrum are antagonists. Antagonists may erroneously be categorized as the opposite of an agonist. But, antagonists are simply silent security that lay in wait to block the specific neurotransmitter agonist they’ve been set for (Stahl et al., 2021).
Between agonist and antagonist, you have a partial agonist. An antagonist also blocks partial agonists. They act more strongly than no agonist but less than a full one. They can be used when less action is needed or if stabilization is the goal (Stahl et al., 2021). Lastly, we have inverse agonist, which is actually on the opposite end of the spectrum from agonist. There is more than just something blocking the receptor to specific agonists with an inverse agonist. An inverse agonist can decrease signal transduction and completely stop an agonist from working on a receptor to the point of causing an opposite reaction (Stahl et al., 2021).
Both ion-gated channels and G-couple proteins use receptors to collect ligands from extracellular space (though there are rare exceptions where the receptors are in the intracellular area). Specific ligands fit perfectly into their bio channel receptor, changing their shape (Weir, n.d.) How they do this, though, is entirely different. Ion channels are closed until a specific ligand attaches to an allosteric site; from there, it can control the opening of the channel (Weir, 2010). The permeability of the plasma membrane is changed, and ions are free to move through. They can cause either hyperpolarization or depolarization (Weir, 2010).
On the other hand, G-couple proteins have seven transmembrane alpha helixes that bind to GTP and GDP. A specific ligand binds to the receptor and causes a conformational change. The GPCR exchanges GDP for GTP, which causes the alpha subunit to separate from beta and gamma, and then they can both interact with target proteins (Weir, 2010.) The alpha unit can activate selected protein and relay signals until the process is stopped by the hydrolysis of GTP, forming GDP and ending the loop (Weir, 2010)
Epigenetics studies molecularly mediated interaction between genomes and the environment (DeSocio, 2016). The mechanism of epigenetics works by altering chromatin, which can then control the expression of a gene (Stahl et al., 2021). The critical distinction between epigenetics and genetics is that epigenetic changes are reversible (Camprodon & Roffman, 2016). Epigenetic studies supply evidence that supports the combination approach of medication, therapy, and education in psychiatry (DeSocio, 2016). This means that epigenetics can help to guide pharmaceutical strategies.
All of this information is valuable to a Nurse Practioner. Being conscious of how the drug class works on the receptor and what pathway we are targeting can be vital to care. Epigenetics also proves crucial as it helps establish a multifaceted approach as ideal in psychiatric care. There are many instances in which this knowledge could be beneficial. One particular example that comes to mind would be in the case of schizophrenia. Dopamine is thought to be the primary neurotransmitter involved (Camprodon & Roffman, 2016). Antipsychotics are typically antagonists that target dopamine receptors, but some are different, like ariprpazole, a partial agonist. So if we find that a typical antipsychotic isn’t working well to control symptoms or causes unwanted side effects, we might try something like aripiprazole that will work a little differently and perhaps help regulate dopamine more evenly.
References
Camprodon, J. A., & Roffman, J. L. (2016). Psychiatric neuroscience: Incorporating pathophysiology into clinical case formulation. In T. A. Stern, M. Favo, T. E. Wilens, & J. F. Rosenbaum. (Eds.), Massachusetts General Hospital Psychopharmacology and Neurotherapeutics. Elsevier.
DeSocio, J. (2016) Epigenetics: An emerging framework for advanced practice psychiatric nursing. Perspectives in Psychiatric Care, 52(3), 201-207. https://doi.org/10.1111/ppc.12118
Stahl, S. M., Grady, M. M., & Muntner, N. (2021). Stahl’s essential psychopharmacology neuroscientific basis and practical applications. Cambridge University Press.
Weir, C. J. (2010). Ion channels, receptors, agonists, and antagonists. Anaesthesia & Intensive Care Medicine, 11(9), 377–383. https://doi.org/10.1016/j.mpaic.2010.06.002
Thanks for your contribution on this week’s topic. Your explanation of the questions was amazing. It is
obvious that it is imperative that the advanced mental health nurse practitioner have full Knowle on
foundational neuroscience. The agonist to antagonist spectrum of action of psychopharmacologic
agents describes the range of effects that these drugs can have on the body. Agonists are drugs that
bind to and activate receptors, while antagonists are drugs that bind to and block receptors (Stahl,
2013). Partial agonists are drugs that bind to and partially activate receptors, while inverse agonists are
drugs that bind to and actually decrease the activity of receptors. The effects of these different types of
drugs on the body can vary widely. For example, an agonist may cause the body to produce more of a
certain chemical, while an antagonist may block the production of that chemical. A partial agonist may
have a weaker effect than an agonist, while an inverse agonist may have the opposite effect of an
agonist (Stahl, 2013).
Ion channels are made up of pores that open and close depending on whether or not a ligand is bound
to the channel, whereas G protein-coupled receptors are made up of a single polypeptide that is
threaded through the membrane. Ion channels are responsible for regulating the flow of ions, while G
protein coupled receptors interact with a wide variety of proteins to produce an intracellular response
(Lian, 2015).
G-protein-joined receptors are contained in seven different transmembrane regions, each of which
contains the neurochemical nebulium receptor (Meaney, 2014).
The degree to which a nerve cell is involved determines the role that epigenetics plays in the functioning
of a medicinal drug (such as therapeutic medications). In the past, the genes that had been inactive for a
long time were made active again, and the genes that had been active for a long time were made
inactive. This led to every favorable and unfavorable growth in the neurological characteristics
(Zhong & Leeder, 2013).
This information is crucial because healthcare professionals will use it to contribute to the development
of new treatments and to better understand the medicine’s short-term and long-term efficacy (Glue et
al., 2020). It is possible to enhance certain circumstances and the patient’s quality of life by beginning
the proper medications as soon as possible; nevertheless, the use of a drug that is not appropriate may
result in damage. They are remembering the effects of the medications, which is essential to the
evaluation of the mental condition and the subsequent course of therapy.
References
Lian, J. B. (2015). undefined. Bone, 81, 731-732. https://doi.org/10.1016/j.bone.2015.05.036.
Meaney, S. (2014). Epigenetic regulation of cholesterol homeostasis. Frontiers in
Genetics, 5. https://doi.org/10.3389/fgene.2014.00311.
Stahl, M. Stephen, (2013). Essential Psychopharmacology. Retrieved from
Paul Glue, Natalie J. Medlicott, Shona Neehoff, Peter Surman, Fred Lam, Noelyn Hung, & Cheung-tak
Hung. (2020). Safety and efficacy of extended-release ketamine tablets in patients with treatment-
resistant depression and anxiety: an open-label pilot study. Therapeutic Advances
Zhong, X., & Leeder, J. (2013). Epigenetic regulation of adme-related genes: Focus on drug metabolism
and transport. Drug Metabolism and Disposition, 41(10), 1721- 1724.