成瘾研究与治疗杂志

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Effects of Perinatal 2,3,7,8-Tetrachlorodibenzo-P-Dioxin Exposure on Development of Taste Preference in Rat Offspring

Nishijo M, Tran NN, Nakagawa H, Hori E, Torii K, Takashi K and Nishijo H

Perinatal 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (TCDD) exposure affects various motivated behaviors controlled by limbic system of the brain in offspring. In this study, effects of perinatal TCDD exposure on taste preference were investigated in the rat offspring whose dams were orally exposed to TCDD on the 15 gestational days. After weaning, offspring were given free access to six amino acid solutions with different tastes (sweet, umami, or bitter), saline (salty taste), and distilled water in a choice paradigm. In the TCDD exposed males, daily food intake was significantly decreased on Postnatal Day (P.D.) 33, whereas no differences of total fluid and any kind of solution intake were found between TCDD exposure and control groups in males. In the exposed females, daily intake of MSG was significantly lower on P.D. 32-34 respectively. Moreover, mean MSG intake rates during P.D. 29-35 was significantly decreased in TCDD exposure females. These results suggest that the TCDD-exposed females need less protein than the control females because of poorer growth than the control females, because MSG has “umami” taste, which reflects preference protein intake. In contrast, daily histidine intake on P.D. 34 was significantly increased in TCDD exposed females, and mean lysine intake rate during PND 29-35 was significantly higher than that of control group. These results suggest that rats preferred bitter taste of histidine and lysine solutions under the chemical stress of TCDD exposure. In conclusion, perinatal TCDD exposure affected development of taste preference of offspring female rats, and more study to clarify neural mechanisms is necessary in future.