Papillae circumvallate

The importance of lipophilicity to bitterness has been well established, both directly and indirectly. The importance of partitioning effects in bitterness perception has been stressed by Rubin and coworkers, and Gardner demonstrated that the threshold concentration of bitter amino acids and peptides correlates very well with molecular connectivity (which is generally regarded as a steric parameter, but is correlated with the octanol-water partition coefficient ). Studies on the surface pressure in monolayers of lipids from bovine, circumvallate papillae also indicated that there is a very good correlation between the concentration of a bitter compound that is necessary in order to give an increase in the surface pressure with the taste threshold in humans. These results and the observations of others suggested that the ability of bitter compounds to penetrate cell membranes is an important factor in bitterness perception. 

Fig. 1 Human bitter taste receptor cells express subsets of TAS2R genes. Dual labelling in situ hybridization of one taste bud in human circumvallate papillae reveals that cells a and b express hTAS2Rl (upper panel). Of the two cells, cell a contains also hTAS2R10 messenger RNA (mRNA), whereas cell b tests negative for hTAS2R10 mRNA...

Dotson CD, Roper SD, Spector AC (2005) PLCbeta2-independent behavioral avoidance of prototypical bitter-tasting ligands. Chem Senses 30 593-600 Farbman AI (1980) Renewal of taste bud cells in rat circumvallate papillae. Cell Tissue Kinet 13 349-357... 

TRC from fungiform papillae and some of the anterior foliate papillae establish synaptic contacts with the chorda tympani (CT) nerve, whereas the posterior parts of the foliate and circumvallate papillae are innervated by the glossopharyngeal (GL) nerve. The possible involvement of gustatory nerves in the LCFA-mediated fat preference has recently been explored in rodents, by studying the impact of bilateral transection of the CT nerve (CTX) and/or bilateral transection of the GL nerve (GLX). 

Guth L. 1957. The effects of glossopharyngeal nerve transection on the circumvallate papilla of the rat. Anat Rec 128 715-731. 

Yang R, Crowley HH, Rock ME, Kinnamon JC. 2000. Taste cells with synapses in rat circumvallate papillae display SNAP-25-like immunoreactivity. J Comp Neurol 424 205-215. 

Fukuwatari, T., Kawada, T., Tsuruta, M., Hiraoka, T., Iwanaga, T., Sugimoto, E. Fushiki, T. Expression of the putative membrane fatty acid transporter (FAT) in taste buds of the circumvallate papillae in rats. 

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