Main Barriers in the Central Nervous System (CNS)
The Central Nervous System (CNS) contains three main barriers: the blood-brain barrier (BBB) which is formed by specialized brain capillary endothelial cells; the barrier between the blood and the cerebrospinal fluid (CSF) that exists at the choroid plexus (CP) epithelial cells; and the arachnoid epithelium presenting the middle layer of the meninges.
The endothelial cells of the BBB restrict the migration of potentially harmful blood-borne agents to the central-nervous tissue, the CP epithelium and the arachnoid epithelium protect the CSF. Tight junctions between endothelial and epithelial cells seal the intercellular spaces and minimize paracellular pathways. Creative Biolabs helps scientists to explore the drug transport mechanism in CNS and provide clues for better research and development of new psychotropic drugs.
Fig.1 The three main barriers in the central nervous system (CNS). (Razzak, 2019)
CSF Transport in the CNS
Several anatomical compartments (ventricles, the subarachnoid space, brain, and spine parenchyma; and the drainage sites.) are involved in the CSF transport process. Scientists administered an emulsion of cinnabar granules into CSF via the lateral ventricles, the subarachnoid space (basal cisterns), and the lumbar intrathecal space of live animals (dog, cats, and rabbits). When injecting the cinnabar dye into the lateral ventricles they observed (post mortem) that it had traveled through the central canal of the spine down to the lumbar region. Ventricular and subarachnoid CSF communicates; and there is free flow between the subarachnoid space of the brain and spinal cord. Choroidal CSF moves from the sites of production through the interventricular foramina to the third and the fourth ventricles via the aqueduct and into the subarachnoid space of the basal cisterns.
In another research, scientists used autoradiographic techniques to show that (14C) AA rapidly penetrated from the blood into the CP and then into CSF and, over time, into the brain surfaces in contact with CSF and then subsequently into deep brain structures. The main route for entry of AA into the brain was by the CP-CSF pathway.
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The poorly penetrable BBB limits passage of drugs from the systemic circulation into the brain. The brain can be further subdivided into several distinct physiological compartments. The specific disposition characteristics across these specific compartments further determine drug target site concentrations. Therefore, more time and energy should be spent on the study of substance transport in the CNS. We can build models of different drug metabolism in the animal brain according to your needs and use mass spectrometry to detect the corresponding indicators. At the same time, we will use imaging techniques, high-performance liquid chromatography, liquid chromatograph-mass spectrometer, radioimmunoassay, and enzyme immunoassay to help you analyze the results.
Creative Biolabs can provide our worldwide customers with high-quality services in terms of systematic analysis of CNS transport. Our outstanding scientists will do their best to meet every customer's requirements. If you have any questions, please contact us.
Reference
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Razzak, R. A.; Approaches to CNS Drug Delivery with a Focus on Transporter-Mediated Transcytosis. International Journal of Molecular ences. 2019, 20(12): 3108. Distributed under Open Access license CC BY 4.0, without modification.
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