A novel method to study cerebrospinal fluid dynamics in rats

Abstract

Background Cerebrospinal fluid (CSF) flow dynamics play critical roles in both the immature and adult brain, with implications for neurodevelopment and disease processes such as hydrocephalus and neurodegeneration. Remarkably, the only reported method to date for measuring CSF formation in laboratory rats is the indirect tracer dilution method (a.k.a., ventriculocisternal perfusion), which has limitations. New Method Anesthetized rats were mounted in a stereotaxic apparatus, both lateral ventricles were cannulated, and the Sylvian aqueduct was occluded. Fluid exited one ventricle at a rate equal to the rate of CSF formation plus the rate of infusion (if any) into the contralateral ventricle. Pharmacological agents infused at a constant known rate into the contralateral ventricle were tested for their effect on CSF formation in real-time. Results The measured rate of CSF formation was increased by blockade of the Sylvian aqueduct but was not changed by increasing the outflow pressure (0–3 cm of H2O). In male Wistar rats, CSF formation was age-dependent: 0.39±0.06, 0.74±0.05, 1.02±0.04 and 1.40±0.06 µL/min at 8, 9, 10 and 12 weeks, respectively. CSF formation was reduced 57% by intraventricular infusion of the carbonic anhydrase inhibitor, acetazolamide. Comparison with existing methods Tracer dilution methods do not permit ongoing real-time determination of the rate of CSF formation, are not readily amenable to pharmacological manipulations, and require critical assumptions. Direct measurement of CSF formation overcomes these limitations. Conclusions Direct measurement of CSF formation in rats is feasible. Our method should prove useful for studying CSF dynamics in normal physiology and disease models.

Modulation of brain cation-Cl− cotransport via the SPAK kinase inhibitor ZT-1a

“…Fluorescence change was plotted as a function of the reciprocal of the relative osmotic pressure and the resulting calibration curve applied to all subsequent experiments as described before 90 Immunoblot and phospho-antibody immunoprecipitation. Whole-cell or cerebrospinal fluid (CSF) lysates were prepared with RIPA lysis buffer as previously described 3,91 . Lysate protein samples were subjected to immunoblot and immunoprecipitation as previously described 25 .…”

“…Body temperature was maintained at 37 ± 1°C (Harvard Apparatus, Holliston, MA, USA) throughout the course of the experiments. PHH was modeled using a modified protocol based on previously described methods 91,95 . Briefly, the tail artery of an anesthetized rat was aseptically cannulated using a flexible catheter (PE-20) preloaded with heparinized saline.…”

“…Quantitation of rates of CSF production and intracerebroventricular drug administration. Rates of CSF production were measured as previously described 91 .…”

Cerebrospinal fluid hypersecretion in pediatric hydrocephalus

“…17,74,88,93 As reviewed earlier, the charge gradient created by transport of positive ions (primarily Na + ) into the ventricular space is balanced by the cotransport of bicarbonate, which is produced by CA in the intracellular compartment. However, the precise mechanism by which acetazolamide reduces CSF production is not completely understood.…”

Regional differences in the ependyma of the optic tectal ventricle of adult zebrafish with structures referring to brain hydrodynamics

“…New studies, aiming to analyze different ependymal regions of different species with sophisticated morphological techniques and/or experimentation with the fluid exchange across the ependyma, describe more complex physiology of the brain fluid spaces and their fluid interactions (Bulat, Lupret, Orehkovic, & Klarica, ; Karimy et al, ; Odeen, Uppman, Markl, & Spottiswoode, ). New literature, using zebrafish embryos also refer to possible communication between the ventricular CSF and the parenchymal ISF (Venero Galanternik et al, ).…”