Dexamethasone reduces food intake, weight gain and the hypothalamic 5-HT concentration and increases plasma leptin in rats.
This study was conducted to define the regulatory mechanisms underlying stress-induced decreases in food intake and weight gain. Rats received a single or 4 daily injections of dexamethasone (0.1 or 1 mg/kg). Food intake and weight gain were recorded, and plasma leptin, brain contents of serotonin (5-hydroxytryptamine; 5-HT), 5-hydroxy-indole-acetic acid (5-HIAA) and the raphe expression of tryptophan hydroxylase (TPH), monoamine oxidase A (MAO-A) and 5-HT reuptake transporter (5-HTT) genes were examined. A single injection of dexamethasone did not acutely affect food intake, but cumulative food intake and weight gain were suppressed dose-dependently by daily injections of dexamethasone. Both a single and repeated injections of dexamethasone elevated plasma leptin in a dose dependent manner. 5-HT contents in the hypothalamus was decreased, but 5-HIAA increased, both by a single and repeated dexamethasone. A single injection of dexamethasone did not affect mRNA expressions of TPH, MAO-A and 5-HTT genes, but repeated dexamethasone increased them in the dorsal raphe nucleus. These results suggest that plasma leptin may play a role in dexamethasone-induced anorexia. Additionally, increased expression of MAO-A and 5-HTT genes by repeated dexamethasone appears to be implicated in decreases of the brain 5-HT contents.
Jahng
Jeong Won
JW
Dental Research Institute, Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul, 110-744, South Korea. jwjahng@snu.ac.kr
Kim
Nam Youl
NY
Ryu
Vitaly
V
Yoo
Sang Bae
SB
Kim
Bom-Taeck
BT
Kang
Dong-Won
DW
Lee
Jong-Ho
JH
D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D007031:Hypothalamus / Q000737:chemistry*; D020738:Leptin / Q000097:blood*; D008297:Male; D008995:Monoamine Oxidase / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000502:physiology; D012701:Serotonin / Q000032:analysis*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics; D014365:Tryptophan Hydroxylase / Q000235:genetics; D015430:Weight Gain / Q000187:drug effects*
D020738:Leptin; D012333:RNA, Messenger; D011985:Receptors, Serotonin; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D003907:Dexamethasone; D014365:Tryptophan Hydroxylase; D008995:Monoamine Oxidase