Serotonin delivery into the ventromedial nucleus of the hypothalamus affects differently feeding pattern and body weight in obese and lean Zucker rats.
OBJECTIVE
To determine if central serotonin (5-HT)-induced satiety is altered in obesity.


METHODS
Obese and lean Zucker rats received infusion of 5-HT (5 microg/0.5 microl/h) or saline into the ventromedial nucleus of the hypothalamus (VMN) for 2 weeks.


RESULTS
In lean rats, 5-HT decreased body weight (7%) and total food intake (15%) which was due to a decreased meal size during the dark phase. In obese rats, a decrease of food intake was also observed in the dark phase, but it was compensated by an increased food intake during the light phase, resulting in no significant changes of total food intake and body weight. In obese rats, meal number but not meal size was affected by 5-HT delivery. Body fat content was not affected by 5-HT in obese rats, while cessation of 5-HT delivery in lean rats resulted in 13% increase.


CONCLUSIONS
Intra-VMN 5-HT in obese rats did not increase meal-associated satiety as it did in lean rats, but modulated hunger. These results show that the Zucker obese phenotype is characterized by VMN resistance to 5-HT, which may contribute to neurobiological mechanisms of increased meal size and food intake and may diminish anti-obesity effects of serotonergic anorexiants.
Fetissov
Sergueï O
SO
Neuroscience Program, Surgical Metabolism and Nutrition Laboratory, Department of Surgery, State University of New York Upstate Medical University, Syracuse, NY 13210, USA. Serguei.Fetissov@univ-rouen.fr
Meguid
Michael M
MM
D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001823:Body Composition / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000187:drug effects*; D004195:Disease Models, Animal; D002149:Energy Intake / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects* / Q000502:physiology; D009765:Obesity / Q000503:physiopathology*; D017440:Photoperiod; D051381:Rats; D011924:Rats, Zucker; D012701:Serotonin / Q000494:pharmacology*; D018490:Serotonin Agents / Q000494:pharmacology; D013851:Thinness / Q000503:physiopathology*; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects* / Q000378:metabolism
D018490:Serotonin Agents; D012701:Serotonin