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High-fat diet decreases tyrosine hydroxylase mRNA expression irrespective of obesity susceptibility in mice

Journal Article


Abstract


  • Tyrosine hydroxylase is the rate-limiting enzyme in the synthesis of dopamine, a key neurotransmitter in the regulation of food intake. This study examined tyrosine hydroxylase mRNA expression in obese mice fed a high-fat diet. After 8 week feeding of high-fat diet mice were classified as diet-induced obese and obese-resistant according to body weight gain. They were then placed on different dietary interventions including a high-fat diet, a low-fat diet and an energy-restricted high-fat diet for six weeks. The control group was fed a low-fat diet. The results revealed that tyrosine hydroxylase mRNA expression was significantly decreased in the ventral tegmental area (VTA), ventromedial hypothalamic nucleus (VMH), and substantia nigra (SN) of the high-fat diet-induced obese (ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 29%, ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 26% and ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 26%) and obese-resistant mice (ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 21%, ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 24% and ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 18%) compared to controls. After switching the diet from high to low-fat diet tyrosine hydroxylase mRNA was increased in the VTA, VMH, and SN of the diet-induced obese mice and in the VMH, and SN of the obese-resistant mice. Energy restriction, even with high-fat feeding, reduced tyrosine hydroxylase mRNA expression in the VTA, VMH, and SN compared to controls. In addition, tyrosine hydroxylase mRNA expression in the VTA, VMH, and SN showed a significant negative correlation with plasma leptin levels. This study suggests that the up- or down-regulation of tyrosine hydroxylase mRNA expression in the VTA, VMH, and SN is mainly due to the intake of macronutrient type rather than body weight.

Authors


  •   Li, Yulin (external author)
  •   South, Timothy (external author)
  •   Han, Mei
  •   Chen, Jiezhong
  •   Wang, Rui (external author)
  •   Huang, Xu-Feng

Publication Date


  • 2009

Citation


  • Li, Y., South, T., Han, M., Chen, J., Wang, R. & Huang, X. (2009). High-fat diet decreases tyrosine hydroxylase mRNA expression irrespective of obesity susceptibility in mice. Brain Research, 1268 181-189.

Scopus Eid


  • 2-s2.0-64549162774

Ro Metadata Url


  • http://ro.uow.edu.au/hbspapers/2170

Has Global Citation Frequency


Number Of Pages


  • 8

Start Page


  • 181

End Page


  • 189

Volume


  • 1268

Abstract


  • Tyrosine hydroxylase is the rate-limiting enzyme in the synthesis of dopamine, a key neurotransmitter in the regulation of food intake. This study examined tyrosine hydroxylase mRNA expression in obese mice fed a high-fat diet. After 8 week feeding of high-fat diet mice were classified as diet-induced obese and obese-resistant according to body weight gain. They were then placed on different dietary interventions including a high-fat diet, a low-fat diet and an energy-restricted high-fat diet for six weeks. The control group was fed a low-fat diet. The results revealed that tyrosine hydroxylase mRNA expression was significantly decreased in the ventral tegmental area (VTA), ventromedial hypothalamic nucleus (VMH), and substantia nigra (SN) of the high-fat diet-induced obese (ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 29%, ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 26% and ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 26%) and obese-resistant mice (ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 21%, ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 24% and ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÿ 18%) compared to controls. After switching the diet from high to low-fat diet tyrosine hydroxylase mRNA was increased in the VTA, VMH, and SN of the diet-induced obese mice and in the VMH, and SN of the obese-resistant mice. Energy restriction, even with high-fat feeding, reduced tyrosine hydroxylase mRNA expression in the VTA, VMH, and SN compared to controls. In addition, tyrosine hydroxylase mRNA expression in the VTA, VMH, and SN showed a significant negative correlation with plasma leptin levels. This study suggests that the up- or down-regulation of tyrosine hydroxylase mRNA expression in the VTA, VMH, and SN is mainly due to the intake of macronutrient type rather than body weight.

Authors


  •   Li, Yulin (external author)
  •   South, Timothy (external author)
  •   Han, Mei
  •   Chen, Jiezhong
  •   Wang, Rui (external author)
  •   Huang, Xu-Feng

Publication Date


  • 2009

Citation


  • Li, Y., South, T., Han, M., Chen, J., Wang, R. & Huang, X. (2009). High-fat diet decreases tyrosine hydroxylase mRNA expression irrespective of obesity susceptibility in mice. Brain Research, 1268 181-189.

Scopus Eid


  • 2-s2.0-64549162774

Ro Metadata Url


  • http://ro.uow.edu.au/hbspapers/2170

Has Global Citation Frequency


Number Of Pages


  • 8

Start Page


  • 181

End Page


  • 189

Volume


  • 1268