Automated collection of conditioned medium from organotypically cultured brain slice

For the analysis of neural activity over a long period of time, the organotypic culture of mammalian brain slices provides excellent specimens. To effectively utilize the slice culture, we developed a device for automatic sampling of the culture medium. This device is a computer-controlled combination of a multichannel peristaltic pump to remove the media from the glass culture containers, a fraction collector designed to allow quick freezing of the samples, and a multichannel syringe pump to deliver new media to the containers. Using this device, substances released as results of neural activities can be collected at regular intervals over several days. We monitored the circadian release of arginine-vasopressin from cultured suprachiasmatic nuclei. We also monitored tonic releases of lactate dehydrogenase from cultured hippocampi phasically treated with an excitotoxin and from those transiently deprived of oxygen/glucose.