Explain the agonist-to-antagonist spectrum of action of psychopharmacologic agents, including how partial and inverse agonist functionality
For this Discussion, review the Learning Resources and reflect on the concepts of foundational neuroscience as they might apply to your role as the psychiatric mental health nurse practitioner in prescribing medications for patients.
- Explain the agonist-to-antagonist spectrum of action of psychopharmacologic agents, including how partial and inverse agonist functionality may impact the efficacy of psychopharmacologic treatments.
- Compare and contrast the actions of g couple proteins and ion gated channels.
- Explain how the role of epigenetics may contribute to pharmacologic action.
- Explain how this information may impact the way you prescribe medications to patients. Include a specific example of a situation or case with a patient in which the psychiatric mental health nurse practitioner must be aware of the medication’s action.
******* REQUIRED READINGS/RESOURCES
-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 (pp. 1–19). Elsevier.
Neurotransmitters and Receptor Theory
Agonist-To-Antagonist Spectrum of Action of Psychopharmacologic Agents
An agonist is a chemical that fixes a receptor and activates it to yield a biological response. However, an antagonist is a group of institutions, characters, or concepts representing or stands in opposition and must be contended by the protagonist (Wager et al., 2017). In other words, the antagonist is an individual or group of persons opposing a protagonist.
The agonist and antagonist’s difference is that agonist causes an action while antagonist opposes an action of the former. Inverse agonist produces a biological response opposite from that of agonist. In pharmacology, partial agonists are medications that fit themselves on a given receptor and activate them. Their efficacy is partial compared to full agonists (Camprodon & Roffman, 2016).
Partial agonists can be used to activate the receptors so that they can respond to medications. Inverse agonists can be used to induce a pharmacological response of the agonist.
Actions of G-Couple Proteins and Ion Gated Channels
G couple proteins receptors, also known as &TM receptors or serpentine receptors, are part of evolutionarily-related proteins, the largest and diverse class of membrane receptors found in the eukaryotes (Meng, Kang & Zhou, 2018). The g couple proteins function as an inbox for messages in peptides, light energy, sugars, lipids, and proteins.
On the other hand, ion gated channels are a group of proteins known as transmembrane ion-channel, which open to permit ions, such as sodium, calcium, potassium, or chloride, to pass through the cell membrane in response to the action of a ligand. The key difference between the two elements is that G protein-coupled receptors have a wide variety of functions, including transmitting signals from many stimuli outside the cell into the cell.
However, ion gated channels are pores in the cell membrane that allow the passage of in and out of the cell. The similarity is that these two elements are fundamental in pharmacology in that they determine how humans respond to certain medications.
Impact of Epigenetics Role in Pharmacologic Action
Epigenetics is the study of how environment and behavior can cause transitions that impact the functions of one’s genes. Unlike genetics, epigenetics changes cannot alter the DNA sequence and are reversible but can change how the body sees the DNA sequence. The role of epigenetics may have a huge contribution to pharmacologic action, especially pharmacokinetics or drug metabolism.
The changes in the expression of enzymes involved in drug metabolism can impact the pharmacokinetic process. For instance, Mestre-Fos et al. (2018) report that minRNAs can help medication behavior by changing the drug’s distribution of metabolism.
Impact of the Information in Drug Prescription
Epigenetic alterations are fundamental in both disease and normal state of a patient. The alterations include phosphorylation, acetylation, methylation, and ubiquitylation of the histone chromatin and the DNA (Mestre-Fos et al., 2018). Few patients respond to standard therapies because of various gene alterations in their cells.
Therefore, when prescribing medications, a caregiver should evaluate the patient’s epigenetics. In mental health, epigenetics can determine the side effects of medications and identify new pharmaceutical targets for treatment (Camprodon & Roffman, 2016). For instance, a drug such as aripiprazole can have an epigenetic effect on a patient’s gene. Hence, when prescribing it, psychiatric mental health should be aware of its action.
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 (pp. 1–19). Elsevier.
Meng, X. Y., Kang, S. G., & Zhou, R. (2018). Molecular mechanism of phosphoinositides’ specificity for the inwardly rectifying potassium channel Kir2. 2. Chemical science, 9(44), 8352-8362. DOI: 10.1039/C8SC01284A
Mestre-Fos, S., Penev, P. I., Suttapitugsakul, S., Ito, C., Petrov, A. S., Wartell, R. M., … & Williams, L. D. (2018). Dynamic G-quadruplexes on the surface of the human ribosome. bioRxiv, 435594. doi: 10.1016/j.jmb.2019.03.010
Wager, T. T., Chappie, T., Horton, D., Chandrasekaran, R. Y., Samas, B., Dunn-Sims, E. R., … & Schmidt, C. J. (2017). Dopamine D3/D2 receptor antagonist PF-4363467 attenuates opioid drug-seeking behavior without concomitant D2 side effects. ACS chemical neuroscience, 8(1), 165-177. https://doi.org/10.1021/acschemneuro.6b00297
Agonist-Antagonist Spectrum of Action of Psychopharmacologic Agents
Foundational neuroscience is one of the crucial backgrounds that mental health practitioners should have. Knowledge in this field allows to increase the understanding of the pathophysiology of mental conditions as well as how the medications affect the central nervous system (Saleh et al., 2016).
An agonist is a chemical or biomolecule which interacts with a cell receptor to produce relevant reaction while an antagonist is substance which reduces or opposes the action of an agonist (Saleh et al., 2016). A drug that has the agonist characteristics often ties to the site of reception and causes the required response. On the other hand, antagonists bind with the receptors and limit such action by reducing the number of sites available for the agonist to bind.
Comparison of Actions of G Couple Proteins and Ion-gated Channels
Due to their charge in them, it is impossible for ions to naturally penetrate membranes. The selective control of ions out of and into neurons is made possible with the decoration of membranes with ion channels (Zamponi, Han, & Waxman, 2016). Binding of a neurotransmitter to a receptor results in the conformational changes that bring about opening of the ion channels.
Ligand gated ion channels are those that are linked to the receptors to allow this opening and closing of the channels (Zamponi, Han, & Waxman, 2016). When patients take up drugs, these drugs often bind with the receptor and ion channel complexes t all the necessary modifications of the ion channels to take place. In a similar way, G-protein receptors activate intracellular signaling pathways to allow for the modulation of the ion channel activities (Zamponi, Han, & Waxman, 2016). G Couple Proteins are known to be the most versatile and largest protein families in the genome of all mammals.
A major difference between the ion-gated channels and the G Couple proteins is the fact that the ion channels work by inducing rapid modifications in the membrane potentials so as to bring about the necessary action potentials, while the G Couple Proteins activate hosts of the diverse signaling cascades so as to produce the necessary action (Stahl, 2013).
The G Couple proteins have the potential to regulate other cellular functions that help in the release of the hormones (Stahl, 2013). On the other hand, ion-gated channels, after generating the required action potentials initiate the process of exocytosis and eventually the release of hormones (Stahl, 2013).
Role of Epigenetics in Pharmacologic Action
Epigenetics is a system of gene regulation in which the expression of genes in an organism is successfully repressed without having to alter its genetic code. This alters the gene expression while the genome sequence remains intact (Younus & Reddy, 2017). In pharmacology, epigenetics can be used to alter the body of patients to make them compatible with rare but effective drugs in the treatment of their conditions (Younus & Reddy, 2017).
How this Information may Impact my Prescriptions to Clients
Among the primary ways in which this information may impact my prescriptions to clients is that I will have higher levels of confidence when dictating various instructions to the patients I have. Specifically, for the patients who have neurology defects, I will be sure to give them relevant background knowledge about the drugs, which may increase their levels of compliance. Also, in case of a condition in which epigenetics could increase the chances of compatibility of the client with various drugs, I will be sure to recommend them to the necessary procedures of epigenetics so as to improve the outcomes of the care process.
Saleh, N., Saladino, G., Gervasio, F. L., Haensele, E., Banting, L., Whitley, D. C., … & Clark, T. (2016). A three‐site mechanism for agonist/antagonist selective binding to vasopressin receptors. Angewandte Chemie, 128(28), 8140-8144.
Stahl, S. M. (2013). Stahl’s essential psychopharmacology: Neuroscientific basis and practical applications (4th ed.). New York, NY: Cambridge University Press *Preface, pp. ix–x
Younus, I., & Reddy, D. S. (2017). Epigenetic interventions for epileptogenesis: a new frontier for curing epilepsy. Pharmacology & therapeutics, 177, 108-122.
Zamponi, G. W., Han, C., & Waxman, S. G. (2016). Voltage-Gated Ion Channels as Molecular Targets for Pain. In Translational Neuroscience (pp. 415-436). Springer, Boston, MA.
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agonist to antagonist spectrum of action of psychopharmacologic agents ncbi
agonist and antagonist drugs example
inverse agonist example
inverse agonist vs antagonist
agonist and antagonist neurotransmitters
partial agonist pharmacology
Agonist and antagonist drugs example
- Morphine - a painkiller that works by activating opioid receptors in the brain and spinal cord.
- Epinephrine - a hormone and neurotransmitter that activates adrenergic receptors to increase heart rate and blood pressure.
- Nicotine - a chemical found in tobacco products that activates nicotinic acetylcholine receptors in the brain, producing feelings of pleasure and alertness.
- Albuterol - a bronchodilator drug that activates beta-2 adrenergic receptors in the lungs, helping to open up airways and ease breathing.
- Insulin - a hormone that activates insulin receptors in cells, promoting the uptake of glucose from the bloodstream to be used for energy.
- Naloxone - an opioid antagonist drug that blocks the effects of opioids by binding to opioid receptors and preventing their activation.
- Propranolol - a beta-blocker drug that blocks beta-adrenergic receptors, reducing heart rate and blood pressure.
- Flumazenil - a benzodiazepine antagonist drug that blocks the effects of benzodiazepines by binding to their receptors in the brain.
- Cimetidine - a histamine H2 receptor antagonist drug that reduces stomach acid production by blocking H2 receptors in the stomach lining.
- Naltrexone - an opioid and alcohol antagonist drug that blocks the effects of opioids and alcohol by binding to their respective receptors in the brain.
Inverse agonist example
- Diphenhydramine (also known as Benadryl) - Diphenhydramine is an antihistamine drug that is used to treat allergies, hay fever, and other conditions caused by histamine release. Diphenhydramine is also a potent inverse agonist at the H1 histamine receptor, which reduces the basal activity of the receptor, leading to sedation and reduced wakefulness.
Inverse agonist vs antagonist
- Buprenorphine - Buprenorphine is a partial agonist at the mu-opioid receptor and is used to treat opioid addiction. Buprenorphine produces less euphoria and respiratory depression than full agonists like heroin or morphine.
- Aripiprazole - Aripiprazole is a partial agonist at the dopamine D2 receptor and is used to treat schizophrenia and bipolar disorder. Aripiprazole produces weaker dopamine receptor activation than full agonists like cocaine or amphetamine.
- Buspirone - Buspirone is a partial agonist at the serotonin 5-HT1A receptor and is used to treat anxiety. Buspirone produces less sedation and fewer side effects than full agonists like benzodiazepines.
Agonist and antagonist neurotransmitters
- Dopamine - Dopamine is a neurotransmitter that is involved in reward and motivation, as well as movement and coordination. Drugs that increase dopamine activity, such as amphetamines or cocaine, act as dopamine agonists and can produce feelings of euphoria and increased energy.
- Serotonin - Serotonin is a neurotransmitter that is involved in regulating mood, appetite, and sleep. Drugs that increase serotonin activity, such as selective serotonin reuptake inhibitors (SSRIs), act as serotonin agonists and are used to treat depression, anxiety, and other mood disorders.
- GABA - GABA is a neurotransmitter that is involved in regulating anxiety and sleep. Drugs that block GABA receptors, such as benzodiazepines, act as GABA antagonists and can produce feelings of relaxation and sedation.
- Acetylcholine - Acetylcholine is a neurotransmitter that is involved in muscle movement, attention, and memory. Drugs that block acetylcholine receptors, such as anticholinergic drugs, act as acetylcholine antagonists and can produce side effects like dry mouth, blurred vision, and cognitive impairment.
- Norepinephrine - Norepinephrine is a neurotransmitter that is involved in the "fight or flight" response, as well as attention and arousal. Drugs that block norepinephrine receptors, such as beta blockers, act as norepinephrine antagonists and can be used to treat high blood pressure, anxiety, and other conditions.