Adenosine release in the preoptic forebrain areas that control sleep assessing the role of astrocytes. (360G-Wellcome-087968_Z_08_Z)

Adenosine is a key endogenous somnogen. I propose that the balance between activity-dependent accumulation of adenosine and its removal by degradative and transport processes sets the basal level of adenosine in the brain throughout the sleep-wake cycle. Glutamate receptor activation is one way that the brain can monitor overall activity levels. Infusion of glutamate receptor agonists into sleep controlling basal forebrain causes adenosine release and enhanced sleep. I shall test the role of ast rocytes in glutamate receptor-dependent release of adenosine in the ventrolateral preoptic area (VLPO) and basal forebrain (BFB). Working in vitro, I shall: 1) determine the dependence of adenosine release on intracellular calcium; 2) test whether there is a causal link between astrocytic calcium signalling and adenosine release; and 3) test whether extracellular adenosine accumulates through prior exocytosis of ATP, the actions of nucleoside transporters, channel mediated mechanisms and the potential involvement of NO-signalling. The outcome of this project will be a determination of the cellular sources and mechanisms of adenosine release in VLPO and BFB. This important advance will set the ground-work for future targeted cell-specific genetic approaches to explore the mechanisms of sleep.