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فالح بن مشبب القحطاني. Faleh Alqahtani, Ph.D

Associate Professor

Associate Professor, Department of Pharmacology and Toxicology

كلية الصيدلة
College of Pharmacy, King Saud University Riyadh, Saudi Arabia. Office: Building 23, first floor, Room 1A30
publication
Conference Paper
2016

Intracereberal Microdialysis Technique for comparing [14C] Sucrose and [13C] Sucrose in Mouse Brain

Bickel, • Faleh Alqahtani, Ekram Ahmed Chowdhury, Raktima Bhattacharya, Reza Mehvar and Ulrich . 2016

Introduction

Blood-brain barrier (BBB) integrity is a critical parameter in the understanding of many CNS disorders. Currently, one of the most commonly used markers for measuring BBB permeability of hydrophilic small molecules is [14C] sucrose. Besides requiring the handling of radioactivity, the presence of low amounts of lipophilic impurities may compromise permeability estimates. We have recently introduced [13 C] sucrose as a superior probe by establishing a highly sensitive and specific LC-MS/MS based assay. The present work aims to validate the superiority of  [13 C] sucrose by using brain micro-dialysis technique. For comparison we also analyzed low molecular weight metabolites.

Methods

In vitro recoveries of customized micro-dialysis probes or commercial probes were first tested in well-stirred solutions of [13C] sucrose, [14C] sucrose or brain metabolites (dialysate flow rate 2µL/min). Then, customized probes were stereotaxically implanted into the striatum of C57BL/6 mice. After 24h, the animals received an IV bolus injection of 10 mg/kg [13C] sucrose or 40μCi/mice. Then, Blood and dialysate samples were collected for 2h. The brain was perfused and collected at the end of experiment.    [13C] Sucrose, [14C] sucrose were analyzed by LC/MS/MS, LSC respectively, while glucose and lactate were analyzed by CMA 600 Microdialysis Analyzer.

Results

The in vitro study of our probes showed approximately 7.5 % recovery for both  [13C] sucrose and [14C] sucrose that was higher when compared to the commercial probes of smaller MW cutoff. Recovery rates of glucose and lactate were 9.7% and 12.6%, respectively. In vivo, brain micro-dialysate concentrations of [13C] sucrose were well above the lower limit of quantification (1 ng/mL). After we confirmed the implantation coordinates, we found similar concentrations of [13C] sucrose and [14C] sucrose in the plasma and higher concentration of  [14C] sucrose in the brain tissue as well as in the brain extracellular space (ECF)

Conclusion

The LC-MS/MS technique is suitable for measuring [13C] sucrose in microdialysate samples even after a low dose of [13C] sucrose, such as 10 mg/kg, has been systemically injected. Low doses in that range would not have any significant physiological effects, e.g. on plasma osmolality. Interestingly, while the plasma profile and AUC for [13C] sucrose and [14C] sucrose are similar, total brain concentration of [14C] sucrose is 6 folds higher and extracellular fluid concentration also is almost 2 folds higher than corresponding values for of  [13C] sucrose. This discrepancy is likely due to the very small amounts of contaminants in [14C] sucrose, which are more lipophilic and penetrate the BBB to a higher extent than pure sucrose.

Conference Name
American Association of Pharmaceutical Scientists, Denver, CO; November 2016
Sponsoring Organization
American Association of Pharmaceutical Scientists
more of publication
publications

Blood Brain Barrier (BBB) permeability is frequently compromised in the course of diseases affecting the central nervous system (CNS). Sucrose is a low molecular weight, hydrophilic marker with…

by Ekram Ahmed Chowdhury, Faleh Alqahtani, Raktima Bhattacharya, Reza Mehvar, Ulrich Bickel
2018
publications

Among small, hydrophilic drug-like molecules, [14C]sucrose has long been considered the gold standard for determination of blood-brain barrier permeability.

by Faleh Alqahtani, Ekram Ahmed Chowdhury, Raktima Bhattacharya, Behnam Noorani, Reza Mehvar, Ulrich Bickel
2018
publications

Introduction

by • Faleh Alqahtani, Ekram Ahmed Chowdhury, Raktima Bhattacharya, Reza Mehvar and Ulrich Bickel
2016