cannabisnews.com: Researchers Study Brain Receptors Linked To Memory





Researchers Study Brain Receptors Linked To Memory
Posted by FoM on December 13, 2000 at 08:07:22 PT
Internet Wire via Comdex
Source: Internet Wire
Cannabinoid receptors in the brain, the point of action for marijuana, don't need that mind-altering substance or any other to activate, according to researchers at the Medical College of Georgia. Dr. Deborah L. Lewis, who is studying CB1, a cannabinoid receptor in the brain, has found that the receptor that can interfere with memory and suppress pain is spontaneously active. 
She's also found that these receptors often dominate other receptors in the cell by hoarding G proteins, which are critical to receptor activation. Now she's trying to find out why. The neuroscientist is studying cannabinoid receptors - so named because, like nicotinic receptors, the scientists who identified them found the environmental substances they react to before finding the endogenous ones - in order to learn the basic steps cells take to communicate. Also, information on how these receptors work may define points of action for drugs that improve memory and control pain. "I am fascinated by how we think and how we have different moods and how we learn," said Dr. Lewis, and also by the cannabinoid receptor CB1, one of the brain's most plentiful receptors for neurotransmitters. "I am interested in how the brain signals, how neurons get their signal and how they process that signal and how they communicate with one another and modulate each other," she said. Neurons communicate by secreting neurotransmitters that bind to receptor proteins on another cell and so forth to rally those cells to enable you to act or think. Cannabinoid receptors are involved in a wide variety of functions, including suppressing memory, pain and the immune system as well as stimulating the appetite and controlling nausea. It was believed that these receptors were inactive until the right neurotransmitter came along to trigger activity. "But we have found we have a different situation where some CB1 receptors already are stimulated so instead of being down at zero, it is signaling at 30 to 40 percent," Dr. Lewis said. She suspects the spontaneous activity is related to the structure of the receptor itself or possibly body heat. Whatever the cause, the fact that the receptor is tonically active means its activity could be turned up or down, depending on the desired result. "The idea this tonic receptor activity leads you to is that if you put a drug on it that's an agonist, to stimulate the receptor, you get more signal. If you put on an antagonist that decreases activity, you could improve memory," Dr. Lewis said. CB1's dominance among receptors may come from its sheer quantity. "Our hypothesis is since they are high density, it's probably likely that they are going to sequester those G proteins to prevent other receptors from signaling but we don't know that yet," Dr. Lewis said. The process begins when the CB1 receptor links with the G protein which then shuts down the calcium channel. Left open, the calcium channel would enable calcium to move from outside the cell inward where it could trigger the release of the neurotransmitter and make it possible for one cell to communicate with the next. However, in the case of CB1 which is working to decrease activity - in a good way to reduce pain but with a negative result by reducing memory - the G protein produces the opposite effect by blocking the calcium channel and keeping the neurotransmitter inactive within the cell. Dr. Lewis, a faculty member in the MCG Department of Pharmacology and Toxicology, has research funding from the National Institute on Drug Abuse. Complete Title: Researchers Study Brain Receptors Linked To Memory, Pain SuppressionContact: Toni BakerMedical College of Georgia706-721-4421Contact: Christine DMedical College of Georgia706-721-4421Source: Internet WirePublished: Wednesday, December 13, 2000 Copyright 2000 Internet WireWebsite: http://www1.internetwire.com/iwire/homeCannabisNews Medical Marijuana Archiveshttp://cannabisnews.com/news/list/medical.shtml
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