Methodology of microdialysis of neostriatum in hemiparkinsonian nonhuman primates

In vivo biochemical microdialysis in primate brain would greatly expand our understanding of functional neuronal systems. This work describes our efforts to establish a microdialysis system in primate brain. Seven anesthetized rhesus monkeys underwent magnetic resonance imaging (MRI) with the head fixed in a compatible stereotaxic frame. This allowed stereotaxic localization of the caudate nucleus and putamen. Guide cannulae were implanted and fixed to the skull. Microdialysis probes made from polyethylene and fused silica were inserted into the caudate and putamen through the guide cannulae and perfused at the rate of 1.3 microliters/min. The putamens were approached horizontally, while the caudate nuclei were reached via a 30 degrees-45 degrees angle from the vertical. Postdialysis MRI and histologic evaluation proved that all probes accurately arrived at the predetermined region. Our data show that MRI guided stereotaxis allows accurate placement of dialysis probes and that implantation of guide cannulae is a reliable and convenient way to perform repeated brain microdialysis procedures.