Most drugs act by being either agonists or antagonists at receptors that respond to chemical messengers such as neurotransmitters. Agonist and antagonists act in the opposite direction. In pharmacology, agonist binds to a receptor and produces a natural action within the cell. While the agonist is stimulating a response, the antagonist is always idle doing nothing. Agonists on the other are drugs that help in blocking the activity of receptors but do not alter the action or response. In some cases, the antagonism may be extreme and competitive hence requiring a high concentration of agonist to fight against it. Insurmountable antagonists, however, bind the receptors actively making it difficult for agonist to reverse the action. Pharmacological receptors are divided into four ligand-gated ion channels, G-protein, direct enzymes and intercellular receptors.
There exist some similarities and difference between the Ion channels and the G-protein depending on the function the receptor does in the cell. The ligand ion gated channels are proteins that contain pores allowing the regulation of selected ions into the plasma membrane ( Alexander et al., 2013). When the nerves send various signals into the body, the ion channels are used in signaling the travel. This effect is accomplished by utilizing the ligand ion channel to mediate fast synaptic transmission from a pre-synaptic neuron to other post-synaptic neurons located in the receptors. G-protein, on the other hand, works by binding a ligand and later releasing a molecule to counter reactions in the body. Mostly, this kind of responses promotes specific activities in the cell. In the heart, for example, the norepinephrine binds its G-protein by activating the adenylate cyclase. This activity helps in the activation of protein kinase hence increasing the contraction strength of the heart. With both the ion gated channels and the G-protein, the ligand always remains outside the cell. Nonetheless, the ion gated channels allow transportation of ions across the plasma membrane while the G-proteins bind any molecules that the nerves do not signal. There is no movement of anything across the plasma membrane in the G-proteins.
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Epigenetics refers to the study of genetic but reversible changes in the genetic composition of a person without modifying the primary DNA sequence ( Ivanov, Barragan, & Ingelman-Sundberg, 2014) . Modification in gene expression is controlled by three main epigenetic mechanics namely; histone modifications, DNA methylation, and microRNAs. These mechanisms play an essential role as they act as regulatory molecules. To achieve this role, they regulate biological functions that relate to homeostasis and allostasis as well as gene expression. Depending on an individual gene composition, epigenetic modifications may lead to various diseases such as autoimmune disorders associated with the skin, cancer, and neurodegenerative diseases such as schizophrenia (Laureate Education, 2012).
Over the years, psychiatrist illnesses are associated with a high prevalence of drug-associated effects and ineffective therapies. The study of the genome and other related information has been crucial in the treatment of psychiatric illnesses. Specific drugs are being used by those patients not responding to traditional therapies due to their genetic composition. This personalized /genomic drug is given to the patients after collecting their genomic information, proteins and their levels of RNA ( Stahl, 2013). The genomic approaches include identification of DNA sequence variations, metabolomics, and others for disease management. In the management of depression, for example, tricyclics are seldom prescribed to patients as it is associated with adverse reactions leading to extreme phenotyping.
References
Alexander, S. P., Peters, J. A., Kelly, E., Marrion, N., Benson, H. E., Faccenda, E., ... & CGTP Collaborators. (2015). The Concise Guide to PHARMACOLOGY 2015/16: Ligand ‐ gated ion channels. British journal of pharmacology , 172 (24), 5870-5903.
Ivanov, M., Barragan, I., & Ingelman-Sundberg, M. (2014). Epigenetic mechanisms of importance for drug treatment. Trends in pharmacological sciences , 35 (8), 384-396.
Laureate Education (Producer). (2012). Introduction to advanced pharmacology [Video file]. Retrieved from https://www.youtube.com/watch?v=lxGB_6EPps4
Stahl, S. M. (2013). Stahl's essential psychopharmacology: neuroscientific basis and practical applications . Cambridge university press.
