Perceptual differences and TAS2R gene polymorphisms

Bitter taste perception is highly individualized in humans (Bartoshuk 2000) and differs among strains of rats (Tobach et al. 1974). These taste differences may influence the diet and health (Tepper 1998) and have therefore attracted much attention. In humans the best-studied example of taste variation is the tasting of PROP and PTC (Guo and Reed 2001). The abilities to taste these two bitter compounds are bimodally distributed in humans, and thresholds of tasting PROP and PTC differ about...

Different Between A8 Fiber And C Fiber Nociceptor

Our bodies sense potentially tissue-damaging stimuli using specialized nerve cells called nociceptors. These are thinly myelinated or unmyelinated slowly conducting C and AS nerve fibers, which connect the peripheral tissue with the central nervous system (CNS). Whenever a noxious stimulus hits such a nociceptor, a generator potential is elicited, which, if it exceeds a certain threshold, evokes an action potential that travels along the peripheral nerve to the spinal cord dorsal horn. Here,...

Synaptic disinhibition in the dorsal horn as a possible source of neuropathic pain

Neuropathic pain results from the damage of neurons or nerves through trauma, poisoning, or metabolic diseases. Damage of peripheral nerves through mechanical injury or metabolic diseases is probably the most frequent cause of neuropathic pain. As in inflammatory pain, the initial focus of research was on peripheral processes. It could be demonstrated that damaged nerves become spontaneously active (Sheen and Chung 1993) and that irregular electric contacts may be formed between nerve fibers...

Identification of TAS2R bitter taste receptor genes

Common knowledge about bitter taste shaped the search strategies of two groups who finally succeeded in cloning the long sought-for genes encoding putative bitter taste receptors (Adler et al. 2000 Matsunami et al. 2000). Firstly, based on the observation that bitter taste transduction is mediated by the G protein a-gustducin (McLaughlin et al. 1992 Wong et al. 1996a, b Ming et al. 1998, 1999 Ruiz-Avila et al. 2000), bitter taste receptors must belong to the GPCR family and expressed in...

A common mechanism in inflammatory and neuropathic pain

Pain Pathway Feedback Loops Spinal Cord

As outlined above, AMPA and NMDA receptors are critically involved in activity-dependent changes in spinal nociceptive processing. Their contribution to the pathogenesis of inflammatory pain or to pain originating from peripheral nerve damage, however, is less clear. Accordingly, recent evidence points to a critical role of disinhibition that is, a reduction in the activity of glycinergic and GABAergic neurons and receptors rather than direct exaggerated excitation as the dominant source of...

Special Issue on Sensory Systems Edited by S Offermanns

Bamberg, Frankfurt S. Grinstein, Toronto S.C. Hebert, New Haven R. Jahn, G ttingen W.J. Lederer, Baltimore R. Lill, Marburg A. Miyajima, Tokyo H. Murer, Zurich S. Offermanns, Heidelberg G. Schultz, Berlin M. Schweiger, Berlin With 16 Figures, 4 in color and 5 Tables Library of Congress-Catalog-Card Number 74-3674 ISSN 030-4240 ISBN-10 3-540-30384-7 Springer Berlin Heidelberg New York ISBN-13 978-3-540-30384-8 Springer Berlin Heidelberg New York This work is subject to...

Transduction mechanisms

The discovery of a-gustducin in the laboratory of Robert F. Margolskee was a milestone in the elucidation of taste transduction mechanisms (McLaughlin et al. 1992). This G-protein subunit, which is closely related to transducin, the G protein of visual sensory transduction, was specifically detected in a subset of taste receptor cells of rodents and humans (McLaughlin et al. 1992 Takami et al. 1994), making it an attractive candidate for transducing taste stimuli. In fact, the participation of...

Tissue distribution

Taste buds occur in the three types of lingual papillae and other parts of the oral cavity. The palate is particularly rich in taste buds in a region called geschmacksstreifen. RT-PCR studies clearly demonstrated the presence of selected rodent and human TAS2R mRNAs in these taste tissues Matsunami et al. 2000 Ueda et al. 2001 Bufe et al. 2002 Behrens et al. 2004 . Fully consistent with the proposed role of the TAS2Rs as taste receptors subsequent in situ hybridization experiments unambiguously...

Phylogeny of TAS2Rs

Sequence comparisons of the human TAS2R genes revealed that genes present on the same chromosome are more closely related to one another than to genes on different chromosomes and the presence of a subfamily of eight TAS2R genes showing particularly high sequence conservation Bufe et al. 2002 . Phylogenetically closer TAS2R genes are also closer in their chromosomal location in mice Shi et al. 2003 , supporting the idea that tandem gene duplications account for the generation of new TAS2Rs....