I. PATHOGNESIS OF CEREBRAL ISCHEMIA: The discovery of ET-1 and NO has greatly contributed to our understanding of the functional changes of many organs under physiological and pathological conditions (e.g., hypertension, atherosclerosis, and stroke). Previous studies focused on interactions of endocannabinoids [2-arachidonoylglycerol (2-AG) and anandamide (ANA) with the vasoconstrictor, endothelin-1 (ET-1). Both 2-AG and ANA are produced in various organs (brain,gut) and cell [monocytes, platelets, endothelial cells (EC)]; they elicit neuromodulator, cytoprotective (i.e., brain ischemia and trauma) and cardiovascular effects, which are mediated through cannabinoid (CB) receptors CB1, CB2 or vanilloid (VR1) receptors. Recently, it has been shown that 2-AG may act as an antioxidant since it suppressed the endotoxin-induced production of TNFalpha. Reactive oxygen species (ROS) were shown to play a role in altering blood-brain barrier (BBB) permeability and formation of brain edema induced by trauma and/or ischemia. Interestingly, 2-AG antioxidant properties have also been implicated to contribute to the improvement of BBB injury and edema formation induced by closed head injury (CHI). The latest in vivo and in vitro studies focus on investigating 1) the possible 2-AG modulation of BBB injury and edema formation induced by closed head injury (CHI); and 2) comparable effects between 2-AG and 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TPL), a known antioxidant nitroxide on endothelial Ca2+ and cytoskeletal responses to H2O2 (ROS). 2-AG treatment reduced the CHI-induced increase in BBB permeability and brain edema. The endothelial H2O2-stimulated Ca2+ mobilization and cytoskeleton (vimentin) rearrangement was modified by either 2-AG or TPL. These findings provide evidence of 2-AG antioxidant activity and are consistent with the involvement of ROS in the pathomechanism of CHI-induced BBB injury and brain edema. Further in vivo and in vitro experiments underway are involved with elucidating the signal transduction mechanisms responsible for the antioxidative properties of 2-AG and alternations of cytoskeleton. II. TOLERANCE TO CEREBRAL ISCHEMIA: The study of SHR-SP tolerization with E-selectin (in collaboration with Dr. J. Hallenbeck) demonstrated a reduced incidence and size of brain infarct and hemorrhage. The latest studies demonstrated that mucosal tolerization renders cell-mediated protection against cerebral damage (stroke). Continued investigation is focused on the mechamism involved in the observed above mentioned phenomena tolerized SHR-SP animals as compared to the Naive rats and whether the E-selectin-induced tolerization against brain injury in SHR-SP rats also effect peripheral organs (i.e., heart and kidneys). In addition, a new initiative for stroke prevention (induction of mucosal tolerance to E-selectin) involves a preclinical study with spontaneously hypertensive, genetically stroke-prone rats and an approved Phase II A Clinical Trial
