Submitted on January 7, 2003
Accepted on July 28, 2003
Pheromone-induced anorexia in male Syrian hamsters
Caurnel Morgan1*, Henryk F. Urbanski2, Wei Fan3, Huda Akil4, and Roger D. Cone3
1 Vollum Institute for Advanced Biomedical Research, Oregon Health and Science University, Portland, Oregon, USA; Mental Health Research Institute, University of Michigan, Ann Arbor, Michigan, USA; Bourne Behavioral Research Laboratory, Department of Psychiatry, Weill Medical College of Cornell University (Westchester Division), White Plains, New York, USA
2 Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon, USA
3 Vollum Institute for Advanced Biomedical Research, Oregon Health and Science University, Portland, Oregon, USA
4 Mental Health Research Institute, University of Michigan, Ann Arbor, Michigan, USA
* To whom correspondence should be addressed. E-mail: cam2025{at}med.cornell.edu.
Transition from long days (LDs) to short days (SDs) triggers seasonal obesity in Syrian hamsters. We report here that SD-exposed males housed near females exhibit obesity resistance, episodic weight loss, and reduced adiposity. Negative energy balance is achieved by reduced eating, elevated motor activity, and increased caloric efficiency, without metabolic compensation. Circulating leptin, insulin, testosterone, corticosterone, and cortisol are normal or reduced in obesity-resistant hamsters. When males are housed in chambers that block physical, visual, and auditory, but not pheromonal, signals from females, resistance to seasonal obesity persists. Moreover, inhalation of extracts from pheromone-releasing flank glands of females suppresses eating and weight gain in SD-exposed males. This novel phenomenon, pheromone-induced anorexia (PIA), shows that female pheromones play a critical role in the seasonal energy balance of male hamsters. These findings provide a model to study neural and endocrine mechanisms that underlie eating disorders.
