Comparative aspects of brain barrier systems for nonelectrolytes

1978 ◽  
Vol 234 (1) ◽  
pp. R52-R60
Author(s):  
H. F. Cserr ◽  
J. D. Fenstermacher ◽  
D. P. Rall
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Barrier Function ◽  
Vertebrate Species ◽  
Detectable Change ◽  
Lemon Shark ◽  
Nurse Shark ◽  
Atlantic Stingray ◽  
The Central Nervous System ◽  
Brain Barriers

Blood-brain and blood-CSF barriers to inulin were compared in 11 vertebrate species. Twenty hours after systemic administration, [14C]inulin penetrated into the central nervous system to an equivalent extent in mudpuppy, salamander (adult and larval), red sculpin, big skate, little skate, southern stingray, and Atlantic stingray with values for RB (dpm/g brain divided by dpm/ml plasma) in the range 0.01- 0.04 and for RCSF (dpm/ml CSF divided by dpm/ml plasma) from 0.02 to 0.04. These values are similar to those reported for mammals. For dogfish, nurse shark, and lemon shark, RB ranged from 0.04 to 0.09 and RCSF from 0.08 to 0.29 and for hagfish RB=0.12, indicating that barrier systems to inulin are poorly developed in sharks and possibly absent in hagfish. Analyses of radiolabeled urea and sucrose penetration into brain and CSF revealed further differences in shark barrier function. Brain barriers to insulin in dogfish and little skate developed with age; in nurse shark there was no detectable change in the inulin ratios over the weight range, 0.2-110 kg.

scholarly journals Macrophages Enforce the Blood Nerve Barrier

2019 ◽  
Author(s):  
Liza Malong ◽  
Ilaria Napoli ◽  
Ian J White ◽  
Salome Stierli ◽  
Alessandro Bossio ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Barrier Function ◽  
Cellular Composition ◽  
Complete Coverage ◽  
Therapeutic Delivery ◽  
The Central Nervous System ◽  
Low Levels ◽  
Cellular Components ◽  
Distinct Role

The specialised blood barriers of the nervous system are important for protecting the neural environment but can hinder therapeutic accessibility1,2. Studies in the central nervous system (CNS) have shown the importance of the cellular components of the neuro-vascular unit for blood-brain barrier (BBB) function. Whilst the endothelial cells (ECs) confer barrier function with specialised tight junctions (TJs) and low levels of transcytosis, pericytes and astrocytes provide complete coverage of the ECs and both deliver essential signals for the development and maintenance of the BBB3–9. In contrast, the blood-nerve barrier (BNB) of the peripheral nervous system (PNS) remains poorly defined10. Here, we show that the vascular unit in the PNS has a distinct cellular composition with only partial coverage of the BNB-forming ECs. Using a mouse model, in which barrier function can be controlled11, we show the BNB, while less tight than the BBB, is maintained by low levels of transcytosis and the TJs of the ECs, with opening of the barrier associated with increased transcytosis. Importantly, we find that while ECs of the PNS have higher transcytosis rates than those of the CNS, the barrier is reinforced by resident macrophages that specifically engulf leaked material. This identifies a distinct role for macrophages as an important component of the BNB acting to protect the PNS environment with implications for improving therapeutic delivery to this tissue.

Ratio of central nervous system to body metabolism in vertebrates: its constancy and functional basis

1981 ◽  
Vol 241 (3) ◽  
pp. R203-R212 ◽  
Author(s):  
J. W. Mink ◽  
R. J. Blumenschine ◽  
D. B. Adams
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Control System ◽  
Functional Relationship ◽  
Muscle Metabolism ◽  
Vertebrate Evolution ◽  
Energy Requirements ◽  
Vertebrate Species ◽  
The Central Nervous System ◽  
Large Animals

We present and document an hypothesis that healthy adults of most vertebrate species use 2-8% of their basal metabolism for the central nervous system (CNS). This relationship is constant across all classes of vertebrates, as we found by examining data from 42 species, including 3 fish, 3 amphibia, 2 reptiles, 6 birds, and 28 mammals. To explain its constancy, we hypothesize that an optimal functional relationship between the energy requirements of an animal's executor system (muscle metabolism) and its control system (CNS metabolism) was established early in vertebrate evolution. Three types of exceptional cases are discussed in terms of the hypothesis: very large animals, domesticated animals, and primates.

scholarly journals Homocysteine and Age-Related Central Nervous System Diseases: Role of Inflammation

2021 ◽  
Vol 22 (12) ◽  
pp. 6259
Author(s):  
Amany Tawfik ◽  
Nehal M. Elsherbiny ◽  
Yusra Zaidi ◽  
Pragya Rajpurohit
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Barrier Function ◽  
Underlying Mechanism ◽  
Age Related Macular Degeneration ◽  
Barrier Dysfunction ◽  
Age Related ◽  
The Central Nervous System ◽  
Underlying Mechanisms

Hyperhomocysteinemia (HHcy) is remarkably common among the aging population. The relation between HHcy and the development of neurodegenerative diseases, such as Alzheimer’s disease (AD) and eye diseases, and age-related macular degeneration (AMD) and diabetic retinopathy (DR) in elderly people, has been established. Disruption of the blood barrier function of the brain and retina is one of the most important underlying mechanisms associated with HHcy-induced neurodegenerative and retinal disorders. Impairment of the barrier function triggers inflammatory events that worsen disease pathology. Studies have shown that AD patients also suffer from visual impairments. As an extension of the central nervous system, the retina has been suggested as a prominent site of AD pathology. This review highlights inflammation as a possible underlying mechanism of HHcy-induced barrier dysfunction and neurovascular injury in aging diseases accompanied by HHcy, focusing on AD.

scholarly journals Approaches to CNS Drug Delivery with a Focus on Transporter-Mediated Transcytosis

2019 ◽  
Vol 20 (12) ◽  
pp. 3108 ◽  
Author(s):  
Rana Abdul Razzak ◽  
Gordon J. Florence ◽  
Frank J. Gunn-Moore
Keyword(s):  
Drug Delivery ◽  
Central Nervous System ◽  
Nervous System ◽  
Surgical Intervention ◽  
Quality Of Data ◽  
Cns Drug Delivery ◽  
The Central Nervous System ◽  
Brain Barriers

Drug delivery to the central nervous system (CNS) conferred by brain barriers is a major obstacle in the development of effective neurotherapeutics. In this review, a classification of current approaches of clinical or investigational importance for the delivery of therapeutics to the CNS is presented. This classification includes the use of formulations administered systemically that can elicit transcytosis-mediated transport by interacting with transporters expressed by transvascular endothelial cells. Neurotherapeutics can also be delivered to the CNS by means of surgical intervention using specialized catheters or implantable reservoirs. Strategies for delivering drugs to the CNS have evolved tremendously during the last two decades, yet, some factors can affect the quality of data generated in preclinical investigation, which can hamper the extension of the applications of these strategies into clinically useful tools. Here, we disclose some of these factors and propose some solutions that may prove valuable at bridging the gap between preclinical findings and clinical trials.

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