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Acta Pharmacologica Sinica 2006 February; 26 (2): 155-159; doi: 10.1111/j.1745-7254.2005.0023.x |
| Original Article | [ Full text ] |
| Orexin A promotes histamine, but not norepinephrine or serotonin, release in frontal cortex of mice1 |
| Zong-yuan HONG2,3, Zhi-li HUANG3,4,5, Wei-min QU3,
Naomi EGUCHI3
2School of Life Science, University of Science and Technology
of China, Hefei 230027, China; |
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Aim: To investigate the effects of orexin A on release of histamine, norepinephrine, and serotonin in the frontal cortex of mice.
Methods: Samples for measuring histamine, norepinephrine, and serotonin contents were collected by in vivo microdialysis of the frontal cortex of anesthetized mice. The histamine, noradrenaline, and serotonin content in dialysates were measured by HPLC techniques. Results: Intracrebroventricular injection of orexin A at doses of 12.5, 50, and 200 pmol per mouse promoted histamine release from the frontal cortex in a dose-dependent manner. At the highest dose given, 200 pmol, orexin A significantly induced histamine release, with the maximal magnitude being 230% over the mean basal release. The enhanced histamine release was sustained for 140 min, and then gradually returned to the basal level. However, no change in norepinephrine or serotonin release was observed under application of the same dose of orexin A. Conclusion: These results suggest that the arousal effect of orexin A is mainly mediated by histamine, not by norepinephrine or serotonin. |
Keywords: orexin A; histamine; noradrenaline; sero-tonin; microdialysis; frontal cortex |
| 1 Project supported in part by a grant-in-aid for scientific research from the Japan Society for the Promotion of Science (ZLH) and Osaka City. |
| 5 Correspondence to Zhi-li HUANG, MD, PhD. Phn 81-6-6872-4851. Fax 81-6-6872-2841. E-mail huangzl@obi.or.jp Received 2004-09-13 Accepted 2004-10-28 |
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