Phosphatidylcholine metabolism is regulated by insulin and insulin-like growth factor in bovine rod outer segment.

SALVADOR, GABRIELA ALEJANDRA; URANGA, ROMINA MARÍA; MATEOS, MELINA VALERIA; PASQUARÉ, SUSANA; GIUSTO, NORMA MARÍA

Atlanta, Georgia, USA

Congreso; Annual Meeting of the American Society for Neuroscience; 2006

Bovine rod outer segments (ROS) are specialized in the phototransduction process. It has been demonstrated that ROS contain Insulin and Insulin-like growth factor (IGF-1) receptors. In addition, Insulin receptor can be activated and phosphorylated by light. The goal of this work was to study the effect of Insulin and IGF-1 on phosphatidylcholine (PC) metabolism in ROS. For this purpose ROS were purified from bovine retinas under dim red light and the incubations with growth factors and exogenous [14C]PC were performed under darkness condition.  Diacylglycerol (DAG), monoacylglycerol (MAG) and free fatty acids (FFA) generated from phosphatidylcholine were separated by thin layer chromatography and quantified by liquid scintillation. Protein tyrosine phosphorylation was determined by western blot. IGF-1 (10nM) and Insulin (175nM) increased tyrosine-phosphorylation of several ROS proteins. Additionally, IGF-1 stimulated MAG generation and inhibited FFA production. On the other hand Insulin provoked an increase in free fatty acid production. Our results demonstrate that Insulin and IGF-1 regulate phosphatidylcholine metabolism in bovine rod outer segments.