www.ijbcp.com International Journal of Basic & Clinical Pharmacology | December 2018 | Vol 7 | Issue 12 Page 2476 IJBCP International Journal of Basic & Clinical Pharmacology Print ISSN: 2319-2003 | Online ISSN: 2279-0780 Review Article Clonidine, dexmedetomidine: alpha-2 adrenergic receptor agonists in neuroscience Jabril B. Eldufani 1 *, Nyruz R. Elahmer 2 , Alireza Nekoui 1 , Gilbert A. Blaise 1,3 INTRODUCTION In the past, there was a scientific theory of adrenergic mechanisms: it was thought that adrenergic receptors consisted of two classes and the actions of these groups resulted in either excitation or inhibition of effector cells. 1 This theory was the accepted concept until Ahlquist demonstrated that there were subtypes of receptors in the class, which he termed α and β1. Researchers later discovered that one of α receptors inhibited neurotransmitter release from the presynaptic neuron (Figure 1). 2 The α-2 adrenergic agonists were developed for their use in clinical practice, including as anesthesia and analgesic adjuncts. The administration of α-2 AR agonists as adjuncts gained popularity, as reported by Brodsky and Bravo in 1976. 2 ABSTRACT The alpha-2 adrenergic receptor (α-2 AR) agonists have a long history of use in treating different clinical conditions, such as hypertension, psychiatric entities (e.g., attention-deficit hyperactivity disorder), chronic pain, panic disorders, and, lately, for treating opioid withdrawal syndrome. In recent years, α-2 AR medications have been administered as adjuncts for managing inflammatory conditions, depression, chronic pain, sleep and cognitive disorders. This review will provide some clinical applications in neuroscience for this class of drugs. Understanding the pharmacological mechanisms is essential to obtaining neurochemical data that demonstrate that α-2 AR agonists have potential clinical significance in neuroscience. Keywords: α-2 AR agonists, Cognitive, Depression, Immune system, Pain, Sleep DOI: http://dx.doi.org/10.18203/2319-2003.ijbcp20184870 1 Department of Medicine, 2 Department of Pharmacology and Physiology, University of Montreal, Montreal, Quebec, Canada 3 Department of Anesthesiology and Pain Management, Management, University Hospital of Montreal (CHUM), Montreal, Quebec, Canada Received: 14 September 2018 Revised: 08 October 2018 Accepted: 12 October 2018 *Correspondence to: Dr. Jabril B. Eldufani, Email: Jabril.Eldufani@ umontreal.ca Copyright: © the author(s), publisher and licensee Medip Academy. This is an open- access article distributed under the terms of the Creative Commons Attribution Non- Commercial License, which permits unrestricted non- commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.