HIV infection frequently results in a dementing illness for which currently there is no effective treatment. The virus infects glial cells but the neurons are rarely infected yet, the uninfected neurons may degenerate. Hence there has been a great interest in developing neuroprotective and neurotrophic drugs that could be used for treatment of HIV dementia. In this project, we will explore two such immunophilin ligands with different mechanisms of actions. Current evidence suggests that they either stabilize intracellular pools of calcium or they prevent mitochondrial toxicity by actions on the mitochondrial transition pore. These drugs are of particular interest to us because we have previously extensively studied the neurotoxic properties of HIV proteins and shown that they cause massive changes in intracellular calcium levels and induce prominent oxidative stress. Using an in vitro human brain model, we will explore the ability of these drugs to protect against the neurotoxicity of HIV proteins and we will determine the mechanisms involved in such neuroprotection. We will also determine if these compounds have neurotrophic effects in this in vitro model when exposed to HIV proteins. Our experimental design will allow us to monitor and compare effects on neuronal and glial cell populations. This project will benefit from our extensive experience with the use of human fetal brain cultures, and in generating recombinant HIV proteins. This is a highly interactive project that will establish important interactions with other in vitro projects examining the use of these drugs for treatment of HIV peripheral neuropathy. Close collaborations with Guilford Pharrmaceuticals will allow us to explore the subcellular mechanisms involved in therapeutic efficacy of these compounds. Information gained from this project will also be critical for monitoring the animal studies and human trials proposed.