Dietary Fat Preferences Are Inversely Correlated with Peripheral Gustatory Fatty Acid Sensitivitya

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Abstract
We previously demonstrated that taste receptor cells (TRCs) respond to cis-polyunsaturated fatty acids (PUFAs) through an inhibition of delayed rectifying K channels (KDR), which may represent the transduction mechanism for dietary fat. To determine if there is a link between the sensitivity of fungiform TRCs to PUFAs and dietary fat preferences, we compared the PUFA-sensitivity of TRCs using patch clamp techniques from Osborne-Mendel (O-M) and S5B/Pl rats, which display dietary preferences for fat over carbohydrate and carbohydrate over fat, respectively. In isolated TRCs, the PUFAs, linoleic (C18:2), linolenic (C18:3) and arachidonic acid (C20:4) inhibit KDR in a concentration-dependent manner in both strains, while the unsaturated lauric acid (C12:0) was ineffective. KDR from TRCs of S5B/Pl rats were significantly more sensitive to inhibition by all three PUFAs (10 microM) than were TRCs from O-M rats. We are currently investigating whether this differential responsiveness is due to (i) the relative affinity of the interaction between cis-PUFAs and the delayed rectifying K channels or (ii) the relative density of delayed rectifying K channels in the two rat strains. Whatever the mechanism, these data suggest an inverse correlation between peripheral gustatory sensitivity to PUFAs and the dietary preference for fat. This finding may provide insight into the mechanism for sensing dietary fat that allows the S5B rats to reduce fat intake on a high-fat diet and avoid the obesity which results when O-M rats eat a high-fat diet.
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