Meeting Abstract
P1.13 Sunday, Jan. 4 Endocannabinoid signaling and energy balance in Siberian hamsters (Phodopus sungorus) HO, J.M.**; DEMAS, G.E.; Indiana University, Bloomington; Indiana University, Bloomington jmho@indiana.edu
Maintenance of energy homeostasis is critical for all organisms and the importance of understanding the control of energy balance is evident in the face of the growing prevalence of human obesity. Siberian hamsters exhibit marked seasonal changes in body weight and food intake, losing ~30% of their body weight in short winter-like day length. Profiles of classical energy balance genes, however, provide little explanation for these dramatic changes. The endocannabinoid (EC) system has been noted for its influence on appetite and energy expenditure, and a well-established literature indicates these effects are mediated by the cannabinoid receptor, CB1. CB1 receptors are widely expressed in the brain and empirical data support the involvement of hypothalamic areas in cannabinoid-induced eating. To date, few studies have examined the influence of cannabinoids on energy balance in a temporal context and no studies have examined EC signaling across energetic state in Siberian hamsters. Thus, we examined seasonal changes in EC signaling and its correlation with body weight in Siberian hamsters. Specifically, we transferred hamsters from long day photoperiod (16 h light:8 h dark) to short day photoperiod (8 h light:16 h dark) and compared them to long day controls at 0, 2, 6, and 12 weeks. Data will be presented on blood EC levels as well as CB1 levels in brain nuclei involved in energy regulation including those of the hypothalamus. The results of this study will contribute to the general understanding of energy regulation. Because these animals naturally fluctuate between energy states comparable to those of obesity and leanness, they serve as an important model for studying the physiological control of energy balance and may provide novel insight to energy regulation not offered by non-seasonal rodent models.
