Research, current brain

Introduction - In last year s chs terl, ray late colleague. Dr. Giaiman and 1 atten te3 to characterize the current status of research on brain neurotransmitter substances. The major topics of that chapter were the basic biochemistry and physiology underlying chemical neurotransmission in the central nervous system (CNS), including a criti of the recent technical ad ces. Because of the emphasis upon the basics of neurotransmitters, we could not dwell vpon the status of information regarding any core neurotransmitter or any one synaptic junction. Therefore, this chapter will deal with the current status of specific central neurotransmitters for particular neuronal junctions. 

Researchers at the MoneU Center (Philadelphia, Pennsylvania) are using a variety of electrophysical and biochemical techniques to characterize the ionic currents produced in taste and olfactory receptor cells by chemical stimuli. These studies are concerned with the identification and pharmacology of the active ion channels and mode of production. One of the techniques employed by the MoneU researchers is that of "patch clamp." This method aUows for the study of the electrical properties of smaU patches of the ceU membrane. The program at MoneU has determined that odors stimulate intraceUular enzymes to produce cycUc adenosine 3, 5 -monophosphate (cAMP). This production of cAMP promotes opening of the ion channel, aUowing cations to enter and excite the ceU. MoneU s future studies wiU focus on the connection of cAMP, and the production of the electrical response to the brain. The patch clamp technique also may be a method to study the specificity of receptor ceUs to different odors, as weU as the adaptation to prolonged stimulation (3). 

There are multiple mechanisms known to underlie the neuronal cell damage associated with injury or disease that at least theoretically could be targeted for pharmaceutical intervention. Currently however, there is no clinically available therapeutic agent that can reliably protect the brain from progressive neurodegenerative processes for sustained periods. Due to the extensive amount of preclinical research that has been conducted in recent years, there is a basis for optimism, however, it appears likely that some of these approaches will result in clinically effective therapeutic modalities in the near future. A short overview of some of the investigational approaches to combat neurodegeneration appears below. 

The epilepsies constitute a common, serious neurological disorder in humans, affecting approximately 60 million people worldwide. Well in excess of 40 distinct epileptic syndromes have been identified to date. Current treatment is only symptomatic except in uncommon instances when surgical treatment is possible. While available antiseizure medications target ion channels such as the y-amino-butyric acid (GABA)a receptor and voltage activated sodium (Na+) channels, current research seeks to elucidate the cellular and molecular mechanisms by which a normal brain becomes epileptic. Hopefully, this research will lead to the identification of new targets for which small molecules can be identified and used for prevention or cure of epilepsy. 

One of the most promising helds of drug research is the search for chemical compounds that can relieve pain. Although the hiomo-lecular process by which pain is produced is not fully understood, scientists now have some important clues. One currently popular hypothesis ties the transmission of pain to a chemical compound known as substance P. Evidence suggests that substance P is a neurotransmitter that carries a "pain message from one neuron to an adjacent neuron. It may he responsible for the transmission of such messages from neurons in the peripheral nervous system to the brain. 

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