| If animals can alleviate hunger, malnutrition or other causes of visceral discomfort after intaking food of a certain taste characteristics, they will increase the intake of this taste stimulus, thus forming conditioned taste preference of this taste(CTP). Behavioral studies have shown that taste stimuli associated with gastric perfusion of energy substances (flavor– Energy associated ) or no-delicious taste stimuli associated with delicious taste stimuli(the flavor - flavor of the association) can make animals form CTP. The use of flavor - the flavor when combined Methods CTP, there are time delay method and the same method when combined Methods established CTP using the flavor-flavor associative method. The former is non-delicious and delicious taste stimuli presented to the animals in accordance with the order. The later is mixture with two kinds of taste stimuli presented to the animals. In experiments of this type, non-delicious taste as the conditioned stimulus, delicious taste as non-conditioned stimulus. Although the animals are given CTP in different ways, but the differences of brain mechanisms are still not clear. Additionally, after animal obtain CTP.It has been not reported that the change of non-conditioned stimuli preference affect the prefence of conditioned stimulus.This experiment use SD rats as experimental subjects, so that rats drink the mixture of citric acid and sucrose method (simultaneous method ) and drink sucrose solution with citric acid solution a (delayed method), respectively.We make rats get sour CTP.And then using drinking sucrose solution and injecting intraperitoneally LiCL combined method, the rats received conditioned taste aversion (CTA).We observe the affect of sweet taste aversion to acid preference. Using immunohistochemistry, we detect the sweet and sour stimuli and observe different influences of c-fos in rat's brain obtained through different methods CTP. The main results are as follows:1. Using given citric acid and sugar mixture with the method (simultaneous method), or given to citric acid solution and drinking sucrose solution methods (delayed method), we could establish CTP of sour in rats. CTP was established by the simultaneous method, the establishment of CTP before and after the sour taste preference ratios were 8.74%±3.27% and 77.36%±12.09%; the ratios of sour preference before and after the establishment of CTP which CTP were established by the delayed method were 7.20%±4.47% and 67.70%±9.09%. CTP established by the delayed method is faster and the average is 20.33±6.22 days, while CTP established by the simultaneous method is slower and the average is 35.86±22.78 days. But the difference between the two was not statistically significant. 2. After CTP of sour is established in rats, when they obtain CTA of sweet, the ratio of the sour preference declines. The ratio of the sour preference established CTP using simultaneous method was 51.03%±12.93%.The ratio of the sour preference established CTP using delayed method was 44.37%±11.00%. The difference was more significant (p <0.01) than before CTA. The same phenomenon also appears in the acid congenital preference rats. The ratio of sour preference declined from 72.45%±11.78% to 55.08%±19.71% after obtained CTA of sweet. The difference was significant. It indicates that the formation of sour preference is related to the sweet analysis system plasticity change of sweet.3. Immunohistochemistry showed that stimulation of sour and sweet taste stimuli can cause a wide range of Fos expression in the brain, including the LPBC, MPBE, LPBE, BLA, Arc, ECu, Pa, PV, etc., suggesting that these brain regions are related to identification of the taste quality, reward evaluation , and related information of sensory information and the integration of behavioral and expressed information ,also shows that the formation of CTP has complex neural mechanism.4. After the establishment of CTP, the expression of Fos induced by sour stimulation in LPBC was an increasing trend.Before the establishment of CTP, fos expression in LPBC induced by the sweet level was significantly higher than fos expression induced by the acid. But after the establishment of CTP, fos expression induced by the sweet and sour is almost the same. It shows that LPBC plays a important role in the identification of taste, reward evaluation and expression of acts.5. Sour stimulation on expression levels of Fos in BLA and Arc is different because of the establishment of CTP in different ways, suggesting different ways obtained CTP is different in the brain mechanism. BLA and the Arc play the different role in the process obtained CTA in different ways.
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