5-hydroxy-L-tryptophan Suppressed Food Intake in Rats Despite an Increase in the Arcuate NPY Expression.
- Author:
Young Wha MOON
1
;
Si Ho CHOI
;
Sang Bae YOO
;
Jong Ho LEE
;
Jeong Won JAHNG
Author Information
- Publication Type:Original Article
- Keywords: food intake; hypophagia; hypothalamus; serotonin
- MeSH: 5-Hydroxytryptophan; Animals; Arcuate Nucleus; Eating; Hypothalamus; Light; Neuropeptide Y; Paraventricular Hypothalamic Nucleus; Protein Kinases; Raphe Nuclei; Rats; RNA, Messenger; Serotonin
- From:Experimental Neurobiology 2010;19(3):132-139
- CountryRepublic of Korea
- Language:English
- Abstract: This study was conducted to define the underlying mechanism of hypophagia induced by increased central serotonergic action. Rats received 3 daily injections of 5-hydroxy-L-tryptophan (5-HTP), a serotonin precursor, at a dose of 100 mg/kg/10 ml saline at 1 h before lights off. A significant suppression in food intake was observed shortly after the 5-HTP injection and persisted during 3 daily 5-HTP injections. Neuropeptide Y (NPY) expression in the arcuate nucleus increased after 3 days of 5-HTP treatment, as high as in the pair-fed group. Immunoreactivity of phosphorylated extracellular signal-regulated protein kinase (pERK1/2) in the hypothalamic paraventricular nucleus (PVN) was increased markedly by 3 days of 5-HTP treatment, but not by 3 days of pair-fed. mRNA expression levels of serotonin reuptake transporter (5-HTT) was increased in the dorsal raphe nucleus of the 5-HTP treated rats, but not in the pair-fed group. Results suggest that increased pERK1/2 in the PVN of 5-HTP injected rats may be a part of serotonergic anorectic signaling, perhaps blunting the orectic action of NPY; i.e., 5-HTP injected rats showed hypophagia despite of increased NPY expression in the arcuate nucleus.
