Les. Author Manuscript Author Manuscript Author Manuscript Author Manuscript Results A significant main effect of strain and diet was observed for body weight with no significant interaction between the two variables. The body weight of the OM rats was greater than the S5B/Pl rats when fed regular chow and both the OM rats and the S5B/Pl rats fed the high-fat diet gained more weight than their regular chow cohorts. To determine whether or not exposure to a high-fat diet for 5-weeks affected the orosensory sensitivity to fatty acids of rats, we examined their 
avoidance of linoleic acid during brief-access gustatory tests following three conditioning days. There was no difference in linoleate BCTC consumption across the 3 conditioning days for the saline-injected groups. The latency until the first lick did not significantly differ between the experimental groups or across J Mol Genet Med. Author manuscript; available in PMC 2015 June 17. Pittman et al. Page 4 concentration or test day indicating that rats did not use olfactory cues to avoid approaching and licking any specific stimuli. As shown in Author Manuscript Author Manuscript Author Manuscript Author Manuscript Discussion The ability of a prolonged high-fat diet to increase fatty acid sensitivity in S5B/Pl rats following a conditioned taste aversion was predicted based on previously reported effects of high-fat diet exposure on the expression of DRK channels in S5B/Pl taste receptor cells. We had also previously reported that OM rats maintained on a normal diet showed stronger taste aversions and slower extinction times than S5B/Pl rats on a normal diet. This behavioral difference corresponded with a reduction in the ratio of fatty acid-sensitive to insensitive DRK channels for OM rats compared to S5B/Pl. Whereas, prolonged exposure to a high-fat diet altered the S5B/Pl ratio of fatty acid-sensitive to insensitive DRK channels such that this strain now expressed a lower ratio of fatty acid sensitive DRK channels than the OM rats on a normal diet. This change in DRK channel expression corresponds with behavioral results showing that when S5B/Pl rats are maintained on a high-fat diet their sensitivity to avoiding linoleate MedChemExpress GLYX13 increases in a manner surpassing the normal-diet OM rats. Specifically, the initial aversion was stronger and more resistant to extinction on the second day of testing for the S5B/Pl rats on the high-fat diet compared to S5B/Pl and OM rats fed a normal diet. Interestingly, there was no observed effect of the high-fat diet on the avoidance of linoleate for the OM rats; however, there was an increase in the innate preference for linoleate in the high-fat diet OM rats receiving saline injections. This control group of OM rats fed the highfat diet licked on average 12% more to the linoleate stimuli than water during testing, whereas their normal-diet cohorts licked the linoleate stimuli 5% less than water. This suggests that exposure to a high-fat diet may influence the preference for fatty acids without affecting the physiological mechanisms underlying the detection sensitivity for fatty acids in the OM 
strain. J Mol Genet Med. Author manuscript; available in PMC 2015 June 17. Pittman et al. Page 5 Our findings are the initial exploration into the ability PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/1985460 of dietary fat content to manipulate fatty acid orosensory detection thresholds with the potential to alter ingestive responses to fatty acids. No observed effects on the latency to lick and our brief-access testing meth.Les. Author Manuscript Author Manuscript Author Manuscript Author Manuscript Results A significant main effect of strain and diet was observed for body weight with no significant interaction between the two variables. The body weight of the OM rats was greater than the S5B/Pl rats when fed regular chow and both the OM rats and the S5B/Pl rats fed the high-fat diet gained more weight than their regular chow cohorts. To determine whether or not exposure to a high-fat diet for 5-weeks affected the orosensory sensitivity to fatty acids of rats, we examined their avoidance of linoleic acid during brief-access gustatory tests following three conditioning days. There was no difference in linoleate consumption across the 3 conditioning days for the saline-injected groups. The latency until the first lick did not significantly differ between the experimental groups or across J Mol Genet Med. Author manuscript; available in PMC 2015 June 17. Pittman et al. Page 4 concentration or test day indicating that rats did not use olfactory cues to avoid approaching and licking any specific stimuli. As shown in Author Manuscript Author Manuscript Author Manuscript Author Manuscript Discussion The ability of a prolonged high-fat diet to increase fatty acid sensitivity in S5B/Pl rats following a conditioned taste aversion was predicted based on previously reported effects of high-fat diet exposure on the expression of DRK channels in S5B/Pl taste receptor cells. We had also previously reported that OM rats maintained on a normal diet showed stronger taste aversions and slower extinction times than S5B/Pl rats on a normal diet. This behavioral difference corresponded with a reduction in the ratio of fatty acid-sensitive to insensitive DRK channels for OM rats compared to S5B/Pl. Whereas, prolonged exposure to a high-fat diet altered the S5B/Pl ratio of fatty acid-sensitive to insensitive DRK channels such that this strain now expressed a lower ratio of fatty acid sensitive DRK channels than the OM rats on a normal diet. This change in DRK channel expression corresponds with behavioral results showing that when S5B/Pl rats are maintained on a high-fat diet their sensitivity to avoiding linoleate increases in a manner surpassing the normal-diet OM rats. Specifically, the initial aversion was stronger and more resistant to extinction on the second day of testing for the S5B/Pl rats on the high-fat diet compared to S5B/Pl and OM rats fed a normal diet. Interestingly, there was no observed effect of the high-fat diet on the avoidance of linoleate for the OM rats; however, there was an increase in the innate preference for linoleate in the high-fat diet OM rats receiving saline injections. This control group of OM rats fed the highfat diet licked on average 12% more to the linoleate stimuli than water during testing, whereas their normal-diet cohorts licked the linoleate stimuli 5% less than water. This suggests that exposure to a high-fat diet may influence the preference for fatty acids without affecting the physiological mechanisms underlying the detection sensitivity for fatty acids in the OM strain. J Mol Genet Med. Author manuscript; available in PMC 2015 June 17. Pittman et al. Page 5 Our findings are the initial exploration into the ability PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/1985460 of dietary fat content to manipulate fatty acid orosensory detection thresholds with the potential to alter ingestive responses to fatty acids. No observed effects on the latency to lick and our brief-access testing meth.
