Shibata Ryoko, Kameishi Makiko, Kondoh Takashi, Torii Kunio
Physiology and Nutrition Group, Institute of Life Sciences, 1-1, Suzuki-Cho, Kawasaki-Ku, Kawasaki 210-8681, Japan.
Physiol Behav. 2009 Mar 23;96(4-5):667-74. doi: 10.1016/j.physbeh.2009.01.002. Epub 2009 Jan 13.
The role of the dopaminergic cells in the ventral tegmental area (VTA) in response to natural rewards is important in understanding palatability-induced feeding behavior. In this study, we first investigated whether dopaminergic lesions in the VTA would influence the taste preferences of rats for sodium chloride (NaCl), monosodium glutamate (MSG), disodium inosine-5'-monophosphate (IMP), disodium guanine-5'-monophosphate (GMP) and sucrose. Among these taste stimuli, only the preference of sucrose solutions decreased significantly in the VTA lesioned rats, preferences for the other taste stimuli were unaffected. Secondly, we tested whether VTA lesioned rats made slightly deficient in the amino acid lysine (by feeding rats a lysine deficient diet for five days) would detect the deficient amino acid in a choice test. Both the VTA lesioned rats and the control rats chose to consume the lysine solution and there was no difference between these two groups. These results suggest that the dopaminergic neurons in the VTA influence sucrose consumption, but do not alter the consumption of palatable umami compounds and salt. They also do not inhibit the animal's ability to recognize the essential amino acid lysine when the animal is deficient in it. Different central pathways must underlie sucrose preference and preferences for these amino acids and ribonucleotides.
腹侧被盖区（VTA）中的多巴胺能细胞对自然奖赏的反应在理解美味诱导的摄食行为方面具有重要意义。在本研究中，我们首先调查了VTA中的多巴胺能损伤是否会影响大鼠对氯化钠（NaCl）、味精（MSG）、5'-肌苷酸二钠（IMP）、5'-鸟苷酸二钠（GMP）和蔗糖的味觉偏好。在这些味觉刺激中，只有VTA损伤大鼠对蔗糖溶液的偏好显著降低，对其他味觉刺激的偏好未受影响。其次，我们测试了VTA损伤大鼠（通过给大鼠喂食五天赖氨酸缺乏饮食使其略缺氨基酸赖氨酸）在选择试验中是否能检测到缺乏的氨基酸。VTA损伤大鼠和对照大鼠都选择饮用赖氨酸溶液，两组之间没有差异。这些结果表明，VTA中的多巴胺能神经元影响蔗糖的消耗，但不会改变美味鲜味化合物和盐的消耗。当动物缺乏必需氨基酸赖氨酸时，它们也不会抑制动物识别赖氨酸的能力。蔗糖偏好以及对这些氨基酸和核糖核苷酸的偏好必定有不同的中枢途径作为基础。
