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- Title
Monoamine Oxidase A Activity and Norepinephrine Level in Hippocampus Determine Hyperwheel Running in SPORTS Rats.
- Authors
Morishima, Masaki; Harada, Nagakatsu; Hara, Sayuri; Sano, Atsuko; Seno, Hiromasa; Takahashi, Akira; Morita, Yusuke; Nakaya, Yutaka
- Abstract
An understanding of neurological mechanisms for wheel running by rodents, especially with high exercise activity, would be applicable to a strategy for promotion of exercise motivation in humans. One of several brain regions that are candidates for the regulation of physical exercise is the hippocampus. Here we examined the running activity of Spontaneously-Running-Tokushima-Shikoku (SPORTS) rat, a new animal model for high levels of wheel-running activity, and its relation with the hippocampal norepinephrine (NE) system including the levels of NE, adrenergic receptors, and degradation enzymes for monoamines. In the hippocampus of SPORTS rats, the level of NE in extracellular fluid was augmented, whereas the level in the homogenate of the whole tissue was decreased even for sedentary conditions. Elevated extracellular NE caused downregulation of α2-adrenergic receptors in the hippocampus of SPORTS rats. Local administration of α2-adrenergic receptor antagonist yohimbine, but not of α2-agonist clonidine, into the hippocampus suppressed high running activity in SPORTS rats. The protein expression and the activity levels of monoamine oxidase A (MAOA), a critical enzyme for the degradation of NE, were decreased in the hippocampus of SPORTS rats to increase extracellular NE level. Thus, inhibition of oxidase activity in normal Wistar rats markedly increased wheel-running activity. These results indicate that decreased MAOA activity, elevation of extracellular NE, and α2-adrenergic receptors in the hippocampus determine the neural basis of the psychological regulation of exercise behavior in SPORTS rats.Neuropsychopharmacology (2006) 31, 2627–2638. doi:10.1038/sj.npp.1301028; published online 18 January 2006
- Subjects
MONOAMINE oxidase; LABORATORY rats; HIPPOCAMPUS (Brain); AMINE oxidase; ADRENERGIC receptors
- Publication
Neuropsychopharmacology, 2006, Vol 31, Issue 12, p2627
- ISSN
0893-133X
- Publication type
Article
- DOI
10.1038/sj.npp.1301028