497. Central CART Gene Delivery by Recombinant AAV Vector Decreases Lean Body Mass in Diet-Induced Obese Male Rats

Cocaine- and amphetamine-regulated transcript (CART) peptide is a neuro-peptide implied in the regulation of energy homeostasis. CART mRNA and its encoded peptide have been localized in many brain regions that regulate energy balance. To study the physiological function of CART in the diet-induced obese (DIO) rats, we constructed and packaged recombinant adeno-associated virus 2 (AAV) vector containing CMV promoter driven rat CART cDNA and a reporter gene hrGFP (AAV-rCART-hrGFP). Approximately 1|[times]|1011 particles of AAV-rCART-hrGFP or control vector AAV-IRES- hrGFP were injected through intra-cerebro-ventricular (ICV) into 100 days old male DIO Long-Evans rats (n=9). Starting on three days post-injection, AAV-rCART-hrGFP-injected rats significantly decreased food intake and body weight gain when compared with that of AAV-IRES-hrGFP-injected rats. AAV-rCART-hrGFP injection modulated hyperphagia following overnight fasting in these rats. Body composition analysis indicated that decreased body weight was due to reduction in lean body mass while fat mass was not different from the control animals. Expression of green fluorescence protein (GFP) suggested that recombinant AAV virions are located at cells around the 3rd ventricle, paraventricle nuclei and medial eminence, external. Our results demonstrate that chronic over-expression of CART in brain can decrease body lean mass by inducing negative energy balance in rats.