Discussion 2: Foundational Neuroscience


Agonist to Antagonist Spectrum

Most drugs act as either agonists or antagonists at receptors in response to chemical messages in the brain.  An agonist, which can be described as partial or inverse, binds to the receptor to produce an effect.  Antagonists also bind to receptors but does not produce a response, rather blocks that receptor to a natural agonist (Pleuvry, 20004).  It is important to acknowledge that agonists and inverse agonists can be reversed by competitive antagonists.  In reference to atypical psychotropic drugs (APD), the blockade of serotonin receptors (5-HT2A) along with the weak antagonism of dopamine receptor (D2) is critical in potency and efficacy, as typical APD have tendency to antagonize D2 receptors more potently than 5-HT2A receptors (Kusumi, Boku, & Takahashi, 2014).

G-coupled Protein and Ion-gated Channels

G-protein linked receptors are important to clinicians with to target specific receptors with psychotropic drugs (Stahl, 2013).  Nonetheless, all agonists do not produce an active state of G-protein-coupled-receptors as in constitutive activity of receptors for benzodiazepines, serotonin, and other G-protein linked receptors.  Contrarily, ion channels function as a result of neurotransmitter ligands at receptors.  Numerous drugs act at ion-channel complexes altering flow of ions through the channels due to the transduction of the signal at receptors (Stahl, 2013).  As a result of the changes of flow of ions, drugs that act on ionotropic receptors tend to act immediately while G-protein linked receptors act at lower frequencies.

Epigenetics in Pharmacologic Action

The lack of response to standard therapies in certain individuals because of various molecular alterations can be due to genetic heterogenecity and epigenetic alterations (Rasool et al., 2015).  Epigenetic modifications can occur as a result of various chemical compounds in the biological system, changing gene expression.  Environmentally and biologically influenced alterations can lead to disorders, therefore clients with epigenetic alterations may require drugs used for personalized medicine based on their personal genomic profile.

Impact on How Medicine is Prescribed

Understanding the agonistic/antagonistic effects of medications along with the prescribing of medications specific to G-protein coupled receptors, and personalized medication profiles required by epigenetic alterations found in certain cases is important to PMHNP’s who may prescribe psychotropic medications to these clients.  Studies have found an existence of constitutive receptor activity in benzodiazepine receptors and G-protein coupled receptors and may be present in mutated strains exhibiting underactive behavior that can lead to inherited diseases such as congenital hypothyroidism and diabetes insipidus (Rasool et al., 2015).  For schizophrenic clients at greater risk for developing extrapyramidal symptoms (EPS), it is known that risperidone equally occupies D2 and 5-HT2A receptors increasing the frequency of EPS, while clozapine more potently occupies 5-HT2A receptors than D2 receptors, rarely producing EPS (Kusumi, Boku, & Takahashi, 2014).  It is the responsibility of the PMHNP to understand their clients’ profiles and medical histories in order to properly prescribe the most effective medications with the least adverse effects.

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