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Brain Res Bull. 2015 Feb;111:48-52. doi: 10.1016/j.brainresbull.2014.11.004. Epub 2014 Dec 16.

L-Ornithine intake affects sympathetic nerve outflows and reduces body weight and food intake in rats.

Author information

1
Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Shiga, Japan.
2
Healthcare Products Development Center, Kyowa Hakko Bio Co., Ltd., Tsukuba 305-0841, Ibaraki, Japan.
3
Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Ishikawa, Japan.
4
Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Shiga, Japan; Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Ishikawa, Japan. Electronic address: mtanida@kanazawa-med.ac.jp.

Abstract

Ingesting the amino acid l-ornithine effectively improves lipid metabolism in humans, although it is unknown whether it affects the activities of autonomic nerves that supply the peripheral organs related to lipid metabolism, such as adipose tissues. Thus, we investigated the effects of l-ornithine ingestion on autonomic nerves that innervate adipose tissues and the feeding behaviors of rats. Intragastric injection of l-ornithine (2.5%) in urethane-anesthetized rats activated sympathetic nerve activity to white adipose tissue (WAT-SNA), and stimulated sympathetic nerve activity to brown adipose tissue (BAT-SNA). In addition, WAT-SNA responses to l-ornithine were abolished in rats with ablated abdominal vagal nerves. l-ornithine ingestion for 9 weeks also significantly reduced rats' body weight, food intake, and abdominal fat weight. Proopiomelanocortin (POMC) levels in the hypothalamus and uncoupling protein 1 (UCP1) levels in brown adipose tissue were significantly increased in rats that ingested 2.5% l-ornithine for 9 weeks. These results suggested that ingested l-ornithine was taken up in the gastrointestinal organs and stimulated afferent vagal nerves and activated the central nervous system. Subsequently, increased hypothalamic POMC activated sympathetic neurotransmission to adipose tissues and accelerated energy expenditure.

KEYWORDS:

Adipose tissue; Afferent vagal nerve; Appetite; Autonomic nervous system; Electrophysiology; Hypothalamus

[Indexed for MEDLINE]

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