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Introduction to Neuroscience

Introduction to Neuroscience

Psychiatric mental health nurse practitioners play a fundamental role in the management of psychiatric disorders. Undeniably, their knowledge regarding the pathophysiology of multifarious mental disorders need to be top notch. However, in addition to the pathophysiological knowhow, PMNHPs need to understand the various mechanisms of action of relevant medications and the manner in which they influence the central nervous system to stabilize the neurochemicals responsible for the existence of these conditions. Thus, PMNHPs require to have knowledge concerning the impact of psychopharmacological medications from their agnostic-to-antagonist spectrum of action. In addition, knowing about the roles of g-coupled proteins and ion gated channels in the entire process of managing mental health conditions becomes an important tool for these nurses. Further, other factors such as epigenetics also influence the pharmacologic action of drugs. As such, a collation of the above information may be fundamental in the prescription of medications to clients; hence, their analysis becomes important.

Agonist-To-Antagonist Spectrum of Action of Psychopharmacologic Agents

            The prescription of psychopharmacological agents occurs based on the mechanisms of action of each molecule. Fundamentally, pharmacological actions of antipsychotics such as agonism and antagonism principally influences neurotransmitters or receptors. According to scholarship on the matter, agonists are referred to as the kinds of drugs or receptor ligands that bind to certain receptors in order to produce the desired therapeutic effect (Lee & Barron, 2017). Specifically, agonists bind to receptors and modulate the activation of the receptors in order to produce the requisite action. The modulation occurs when the agonists alter the conformation of the receptor in order to optimally open the ion channel as well as induce the maximum frequency of the receptors for binding purposes. As a consequence, a maximum downstream signal transduction that has the capacity to be mediated by a receptor occurs.

The above spectrum then moves to antagonists, which are utilized to stabilize the receptor to the resting phase. In other words, the antagonists are used to return ta receptor to its state when the agonists were not available. However, the resting state occasioned by the antagonists still has certain levels of ion flowing through the channel since the ion channel is not fully closed. Therefore, the agonist-to-antagonist spectrum of pharmacological agents entails agonists that open a receptor channel to maximal frequency and amount via antagonists that retain the resting state of a receptor, and lastly to inverse agonists that close and inactivate the receptor ion channel (Stahl, 2013). In between the antagonists and agonists are partial agonists that partially influences the receptor ion channels in comparison to the two. Further, antagonists have the potential to block everything within the agonist spectrum thus ensuring that the ion channel returns to its resting state. Thus, psychopharmacological agents assume this spectrum when addressing certain mental health conditions.

Comparison of the Actions of G Couple Proteins and Ion Gated Channels

            Ion channels are important as regards the selective movement of particular ions across the membrane. One of the types of ion channels include the G couple proteins and ion gated channels. According to studies, both channels are proteins in nature and are embedded within cell membranes and they allow for the passage of ions. G Couple Proteins are composed of a continuous chain having 7 lipophilic helical segments inside the membrane, which allows it to become activated by numerous chemical messengers (Stahl, 2013). Further, the G Protein Couple Receptors are affected by two signal transduction pathways entailing Phosphatidylinositol signal pathway and cAMP signal pathway (Li, Wong, & Liu, 2014). On the other hand, whereas ion channels similarly comprise lipophilic helices in their structures, they attach to different chains hence numerous variants exist. Also called ligand gated channels, ion gated channels experience conformation alteration when a ligand is attached to them leading to the opening of a channel along the membrane to permit the passage of a specific molecule. Thus, unlike the g coupled proteins, the ion gated channels only activates certain ion neurotransmitters to allow for the conductance of specific ions.

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Role of Epigenetics in Pharmacologic Action

            The pharmacology of epigenetics has assumed significance when it comes to the management of brain disorders. The concept refers to the alterations that result in heritable changes regarding the expression of the gene independent of alterations in the genetic sequence. Studies have demonstrated that epigenetics modulates methylation, ubiquitylation, phosphorylation, as well as acetylation of the deoxyribonucleic acid (DNA) (Valor, 2015). As a consequence, the manner in which the body reacts to standard therapeutic interventions via pharmacological agents is affected. Other studies have revealed that epigenetics changes the remodeling of the chromatin affecting both the response of a patient’s body to a prescription drug as well as diagnostic testing for various conditions.

How This Information Impact the Way Medications are Prescribed

            The information above plays a crucial role in the manner in which PMNHP selects medicines for psychiatric patients. During such an exercise, the genetic makeup of a patient as it relates to their ethnicity as well as drug interactions become important. The decision to choose a certain drug will be influenced by the response of a patient as some of them may develop allergies alongside adverse reactions to a drug. For instance, while prescribing lithium 1200mg/day for a patient with type 1bipolar disorder, one must be aware of associated side effects that might impede compliance during care management. Hamlat, O’Garro-Moore, Alloy, and Nusslock (2016) posit that in as much lithium carbonate medication stabilizes manic episodes for patients with bipolar disorder, it can also aggravate vomiting, bilateral hand tremors, and ataxia which can comprise self-medication.

 

 

References

Hamlat, E. J., O’Garro-Moore, J. K., Alloy, L. B., & Nusslock, R. (2016). Assessment and Treatment of Bipolar Spectrum Disorders in Emerging Adulthood: Applying the Behavioral Approach System Hypersensitivity Model. Cognitive and behavioral practice23(3), 289-299.

Lee, S., & Barron, M. G. (2017). Structure-Based Understanding of Binding Affinity and Mode of Estrogen Receptor α Agonists and Antagonists. PLoS ONE, 12(1), 1–14. https://doi.org/10.1371/journal.pone.0169607

Li, S., Wong, A. H., & Liu, F. (2014). Ligand-gated ion channel interacting proteins and their role in neuroprotection. Frontiers in cellular neuroscience, 8, 125. doi:10.3389/fncel.2014.00125

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

Valor, L. M. (2015). Epigenetic-based therapies in the preclinical and clinical treatment of Huntington’s disease. International Journal of Biochemistry & Cell Biology, 67, 45–48. https://doi.org/10.1016/j.biocel.2015.04.009

 

The Agonist-to-Antagonist Spectrum of Action of Psychopharmacologic Agents

The agonist-to-antagonist spectrum is made up of two words that are important to be understood singly. An agonist is a chemical that binds to a receptor thereby activating it to trigger a biological response.  Antagonist, on the other hand, blocks the response mediated by the agonist. Antagonist causes an action opposite to that of the agonist, which reaction is called reverse agonist, to occur (Stahl, 2013). Once an agonist binds to a receptor, a full/conventional or partial agonist reaction may occur. As the concentration of the agonist increases, the occupancy of receptors also increases, consequently increasing the response (Stahl, 2013). The antagonist effect of a drug occurs when the antagonist increases in concentration thereby surmounting the activation effect of the agonist and inhibiting their response. A full agonist produces the maximal response system while a partial agonist produces a submaximal one.

The Actions of G-Couple Proteins and Ion-Gated Channels

There are two broad families of protein receptors involved in the opening and closing of the postsynaptic ion channels, namely g-couple proteins and ion-gated channels (Laureate Education Producer, 2016i). G protein-coupled receptors/seven transmembrane (7-TM) receptors form the largest protein family (about 600 – 1000 members) and are involved in many normal biological and pathological conditions (Inanobe & Kurachi, 2014). They have a diverse function and recognize many ligands including proteins, small molecules, and photons (Stahl, 2013). They specifically maintain the electrochemical gradient across the cell.

Ligand-gated ion channels (LGICs), on the other hand, are transmembrane ion channels found in the cellular membrane. They help in the opening and closing of the membrane to allow for the passage of ions such as Na+, K+, Ca2+, and/or Cl−. The human genome has over 400 genes for ion channels. Their opening and closing are dependent on the attachment of a chemical messenger, a ligand, such as a neurotransmitter (Inanobe & Kurachi, 2014).

The Role of Epigenetics in Pharmacologic Action

Different patients respond differently to various medications due to the genetic alterations that occur at an individual level. Epigenetic allows the understanding of these modifications in gene expressions that occurs in the DNA sequence of a gene for some patients. These genetic modifications are called epigenetic alterations. They include methylation, phosphorylation, acetylation, and ubiquitylation of DNA (Swathy & Banerjee, 2017). These alterations make many patients not to respond to standard therapies. The alterations not only regulate gene expression but also other cellular and biological functions related to allostasis, homeostasis, and disease (Rasool et al., 2015). These processes generally influence pharmacogenetics activities such as the contribution of receptors, drug transporters, and drug-metabolizing enzymes.

Impacts of Epigenetics in Pharmacologic and Examples of Psychiatric Mental Health Cases

The epigenetic alterations that occur at individual levels require doctors to provide personalized treatments to patients. Since epigenetic alterations differ from one patient to the other, physicians should do genetic screenings of patients to guide disease prediction and prevention and decision making on the medical recommendations and lifestyle and disease management practices that are best at an individual level (Rasool et al., 2015). For instance, in the case of Schizophrenia, the genetic modifications occur in the histones or DNA such as DNA methylation. For histone modification, HDAC (histone deacetylase) inhibitors drugs are recommended because they up-regulate the levels of reelin and GAD67. HMT (histone demethylase) inhibitors also prevent the demethylation of the H3K4 histone protein. As for DNA methylation, DNMT (DNA Methyltransferases) inhibitors are recommended because they raise the reeling levels of proteins and protein and GAD67 (Swathy & Banerjee, 2017). This requires physicians to make an individual genetic screening of a patient to determine the particular epigenetic alteration they experience before recommending drug prescriptions that are best and specific to them.

References

Inanobe, A., & Kurachi, Y. (2014). Membrane channels as integrators of G-protein-mediated signaling. Biochimica Et Biophysica Acta (BBA)-Biomembranes, 1838(2), 521-531.

Laureate Education (Producer). (2016i). Introduction to psychopharmacology [Video file]. Baltimore, MD: Author.

Rasool, M., Malik, A., Naseer, M. I., Manan, A., Ansari, S. A., Begum, I., & Kamal, M. A. (2015). The role of epigenetics in personalized medicine: challenges and opportunities. BMC medical genomics, 8(S1), S5.

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

Swathy, B., & Banerjee, M. (2017). Understanding epigenetics of schizophrenia in the backdrop of its antipsychotic drug therapy. Epigenomics, 9(5), 721-736.