Neurotransmitter and Receptor Theory

Agonist-to-antagonist Spectrum of Psychopharmacologic Agents

An agonist is a drug or molecule that binds to and activates its specific receptor to produce a desired biological response. Endogenous agonists are those synthesized within the body, whereas exogenous agonists are from external sources and include various medications that mimic the actions of the endogenous agonists. Agonists can be classified into various categories, namely full agonists, partial agonists, and inverse agonists, depending on the intrinsic efficacy.

Neurotransmitter and Receptor Theory

A full agonist has high intrinsic efficacy and thus produces maximal receptor activation with a resultant maximal intended response. A partial agonist has relatively lower intrinsic efficacy and thus produces sub-maximal receptor activation and resultant weaker biologic response. An inverse agonist, despite binding the same receptor site as the agonist, has a negative intrinsic efficacy in that it produces a biologic response that is antagonistic or opposite to that of the agonist (Berg & Clarke, 2018).

In contrast to an agonist, an antagonist does not have any intrinsic efficacy but has an affinity to receptors and acts to inhibit the effects of agonists. The agonist-to-antagonist spectrum has implications on the choice of psychopharmacological agents depending on the drug’s intrinsic activity and affinity, which translates to the desired therapeutic effect.

Comparison Of G Couple Proteins And Ion Gated Channels

G protein-coupled receptors (GPCRs) and ion gated channels (IGCs) are receptors that usually mediate cellular responses through the activation by stimuli. GPRCs function through second messenger systems and are more abundant compared to IGCs. Ligand-binding activation causes these receptors to bind to G-proteins, which facilitate the exchange of GTP for GDP, leading to a cascade of activities that cause a cellular response (Weis et al., 2018).

IGCs are trans-membrane proteins with a central pore that opens and close to control the movement of ions across the cell membrane (Phillips et al., 2020). Generally, response to a signal is slower in GPCRs due to the coupling and is activated by slower neurotransmitters such as serotonin. IGCs are activated by faster neurotransmitters such as acetylcholine, translating to a quicker response.

Role Of Epigenetics In Pharmacologic Action

Epigenetics is increasingly being adopted in the development of therapeutic pharmacological agents. Epigenetics is whereby DNA transcription is regulated through DNA methylation or histone modification without inflicting any changes to the DNA sequence (Kringel et al., 2021). This results in increased or decreased transcription of the target genes or exposure of desired parts of the DNA through conformational changes to transcription factors.

Drugs can thus be developed to target certain genes that contribute to the etiology of various diseases, including psychiatric illnesses. However, the efficacy of these therapeutic epigenetic pharmacologic agents and expected responses may depend on the presence or alteration of the target genes among individuals; thus, variability is expected in such instances.

Impact Of The Above Information On Prescription Of Medications To Patients

In light of the above information, it is important to know the genetic background of an individual before treatment. This is because certain genes are heritable, most commonly encountered within the hospital setting as a positive family history of a certain illness.

It is thus important to obtain a comprehensive medical and family history before treatment. Genetic testing should also be considered, especially with several treatment failures. Genetic and environmental factors influence epigenetics; thus, it is important for medical professionals to understand this. For example, similar illnesses in twins may not respond similarly to treatment hence the need to individualize care.

References

  • Berg, K., & Clarke, W. (2018). Making Sense of Pharmacology: Inverse Agonism and Functional Selectivity. International Journal Of Neuropsychopharmacology, 21(10), 962-977. https://doi.org/10.1093/ijnp/pyy071
  • Kringel, D., Malkusch, S., & Lötsch, J. (2021). Drugs and Epigenetic Molecular Functions. A Pharmacological Data Scientometric Analysis. International Journal Of Molecular Sciences, 22(14), 7250. https://doi.org/10.3390/ijms22147250
  • Phillips, M., Nigam, A., & Johnson, J. (2020). The interplay between Gating and Block of Ligand-Gated Ion Channels. Brain Sciences, 10(12), 928. https://doi.org/10.3390/brainsci10120928
  • Weis, W. I., & Kobilka, B. K. (2018). The Molecular Basis of G Protein-Coupled Receptor Activation. Annual Review of Biochemistry, 87, 897–919. https://doi.org/10.1146/annurev-biochem-060614-033910

Neurotransmitter and Receptor Theory Instructions

   NURS 6630 Module 2 Week 2: Neurotransmitters and Receptor Theory Receptors and neurotransmitters are like a lock-and-key system. Just as it takes the right key to open a specific lock, it takes the right neurotransmitter to bind to a specific receptor. Not surprisingly, as it concerns psychopharmacology, the pharmacotherapeutics that are prescribed must trigger the release of certain neurotransmitters that bind to the correct receptors in order to elicit a favorable response for the patient. The mechanism of this binding and the response that follows reflects receptor theory and lies at the foundation of pharmacology. This week, you will continue your examination of neuroanatomy and neuroscience as you engage with you colleagues in a Discussion. You will also explore the potential impacts of foundational neuroscience on the prescription of pharmacotherapeutics. Learning Objectives Students will: •	Analyze the agonist-to-antagonist spectrum of action of psychopharmacologic agents •	Compare the actions of g couple proteins to ion gated channels •	Analyze the role of epigenetics in pharmacologic action •	Analyze the impact of foundational neuroscience on the prescription of medications   Learning 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.    The University of British Columbia. (n. d.). Neuroanatomy videos. http://neuroanatomy.ca/videos.html Note: Please review all of the media under the neuroanatomy series.   Pathopharmacology: Disorders of the Nervous System: Exploring the Human Brain Dr. Norbert Myslinski reviews the structure and function of the human brain. Using human brains, he examines and illustrates the development of the brain and areas impacted by disorders associated with the brain. (15m) Accessible player --Downloads--Download Video w/CCDownload AudioDownload Transcript Introduction to Advanced Pharmacology In this media presentation, Dr. Terry Buttaro, associate professor of practice at Simmons School of Nursing and Health Sciences, discusses the importance of pharmacology for the advanced practice nurse. (6m) Accessible player --Downloads--Download Video w/CCDownload AudioDownload Transcript   Discussion: Foundational Neuroscience As a psychiatric and mental health nurse practitioner, it is essential for you to have a strong background in foundational neuroscience. In order to diagnose and treat patients, you must not only understand the pathophysiology of psychiatric disorders but also how medications for these disorders impact the central nervous system. These concepts of foundational neuroscience can be challenging to understand. Therefore, this Discussion is designed to encourage you to think through these concepts, develop a rationale for your thinking, and deepen your understanding by interacting with your colleagues.   Photo Credit: Getty Images/Cultura RF 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.  By Day 3 of Week 2 Post a response to each of the following: 1.	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. 2.	Compare and contrast the actions of g couple proteins and ion gated channels. 3.	Explain how the role of epigenetics may contribute to pharmacologic action. 4.	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.  Excellent  Point range: 90–100	Good  Point range: 80–89	Fair  Point range: 70–79	Poor  Point range: 0–69 Main Posting:  Response to the Discussion question is reflective with critical analysis and synthesis representative of knowledge gained from the course readings for the module and current credible sources.	40 (40%) - 44 (44%) Thoroughly responds to the Discussion question(s).  Is reflective with critical analysis and synthesis representative of knowledge gained from the course readings for the module and current credible sources.  No less than 75% of post has exceptional depth and breadth.  Supported by at least three current credible sources.	35 (35%) - 39 (39%) Responds to most of the Discussion question(s).  Is somewhat reflective with critical analysis and synthesis representative of knowledge gained from the course readings for the module.  50% of the post has exceptional depth and breadth.  Supported by at least three credible references.	31 (31%) - 34 (34%) Responds to some of the Discussion question(s).  One to two criteria are not addressed or are superficially addressed.  Is somewhat lacking reflection and critical analysis and synthesis.  Somewhat represents knowledge gained from the course readings for the module.  Post is cited with fewer than two credible references.	0 (0%) - 30 (30%) Does not respond to the Discussion question(s).  Lacks depth or superficially addresses criteria.  Lacks reflection and critical analysis and synthesis.  Does not represent knowledge gained from the course readings for the module.  Contains only one or no credible references. Main Posting:  Writing	6 (6%) - 6 (6%) Written clearly and concisely.  Contains no grammatical or spelling errors.  Adheres to current APA manual writing rules and style.	5 (5%) - 5 (5%) Written concisely.  May contain one to two grammatical or spelling errors.  Adheres to current APA manual writing rules and style.	4 (4%) - 4 (4%) Written somewhat concisely.  May contain more than two spelling or grammatical errors.  Contains some APA formatting errors.	0 (0%) - 3 (3%) Not written clearly or concisely.  Contains more than two spelling or grammatical errors.  Does not adhere to current APA manual writing rules and style. Main Posting:  Timely and full participation	9 (9%) - 10 (10%) Meets requirements for timely, full, and active participation.  Posts main Discussion by due date.	8 (8%) - 8 (8%) Posts main Discussion by due date.  Meets requirements for full participation.	7 (7%) - 7 (7%) Posts main Discussion by due date.	0 (0%) - 6 (6%) Does not meet requirements for full participation.  Does not post main Discussion by due date.