Real-Time Dynamic Collection of Hippocampal Extracellular Fluid from Conscious Rats Using a Microdialysis System

Hippocampal extracellular fluid and crowd by brain microdialysis technique contributes to monitor the disease specific micro of central nervous diseases. Brain microdialysis technical achieves dynamic and the continuous inquisition of interstitial brain fluid in specific brain regions of non-anesthetized rats. Begin by fixing the anesthetized rat on a stereotaxic brain locator and wipe the shaved surgical area with a povidone iodine and ethanol swab three times before the operation.

Then make a 1.5 centimeter cranial facial incision down the middle with surgical scissors and remove the periosteum using surgical scissors and ophthalmic forceps. Considering the bregma as the basal position, using a cranial drill pierce the endocranium to drill a two millimeter aperture at the hippocampal CA1 region. Now fix the catheter stilette on the gripper of a stereotaxic brain locator and adjust the position of the microdialysis casing at the anteroposterior, mediolateral, and dorsal ventral positions.

Adjust the dorsoventral valve of the brain stereo locator and implant the microdialysis casing into the CA1 region at a depth of 3.5 millimeters. Drill three more apertures with a two millimeter diameter such that the three apertures form a triangle in which the probe aperture is centrally-located. Implant screws into the apertures at a depth of one millimeter and fix the probe catheter with dental cement.

Then use a 4-O surgical suture to close the skin. Connect the microdialysis pump microsyringe with ACSF awake activity device and cryogenic sample collector according to the manufacturer's instructions. Next, to discharge the air in the pipeline, set the microdialysis pump at a rate of one microliter per minute.

Then connect the pipeline and brain microdialysis probe and operate the microdialysis pump at a rate of one microliter per minute to inject ACSF into the probe until the surface of the probe is slightly moist. Immerse the probe in a heparin sodium injection solution for subsequent use. To collect the HECF from the awake rat, insert the brain microdialysis probe into the probe catheter and place the rat in a chamber with padding to ensure the rats are free to move around.

Turn on the multi-channel swivel controller to avoid intertwining the microdialysis pipelines during the free movement of the rat. Then turn on the microsyringe pump and pump the ACSF at a rate of one microliter per minute. After a 60 minute equilibration of the microdialysis HECF collection system, collect HECF periodically.

After sampling termination, take the brain microdialysis probe out from the probe catheter. Immerse the probe in deionized water and lavage with deionized water for 12 hours to remove stranded salt depositions from the pipeline and the probe. Remove the probe and place it into a 0.05%tripsin solution at four degrees Celsius.

Hippocampal extracellular fluid acquired by the brain microdialysis technique is water-like, colorless, and transparent at the set sampling rate. The most important procedures are implanting the microdialysis carefully into the CA1 region and inserting the probe into the pop catheter. The microdialysis simply technique makes it possible to assist the dynamical change of disease markers in specific brain regions, the substance of drug's efficacy, and the tissue catabolism of drug components.