scholarly journals A circadian clock in the blood-brain barrier regulates xenobiotic efflux from the brain

2017 ◽  
Author(s):  
Shirley L. Zhang ◽  
Zhifeng Yue ◽  
Denice M. Arnold ◽  
Amita Sehgal
Keyword(s):  
Gap Junctions ◽  
Blood Brain Barrier ◽  
Time Of Day ◽  
Brain Barrier ◽  
Circadian Regulation ◽  
List Type ◽  
Intracellular Magnesium ◽  
Therapeutic Implications ◽  
Blood Brain ◽  
The Central Nervous System

HighlightsThe Drosophila BBB displays a circadian rhythm of permeabilityCyclic efflux driven by a clock in the BBB underlies the permeability rhythmCircadian control is non-cell-autonomous via gap junction regulation of [Mg2+]iAn anti-seizure drug is more effective when administered at nightSummaryEndogenous circadian rhythms are thought to modulate responses to external factors, but mechanisms that confer time-of-day differences in organismal responses to environmental insults / therapeutic treatments are poorly understood. Using a xenobiotic, we find that permeability of the Drosophila “blood”-brain barrier (BBB) is higher at night. The permeability rhythm is driven by circadian regulation of efflux and depends upon a molecular clock in the perineurial glia of the BBB, although efflux transporters are restricted to subperineurial glia (SPG). We show that transmission of circadian signals across the layers requires gap junctions, which are expressed cyclically. Specifically, during nighttime gap junctions reduce intracellular magnesium ([Mg2+]i), a positive regulator of efflux, in SPG. Consistent with lower nighttime efflux, nighttime administration of the anti-epileptic phenytoin is more effective at treating a Drosophila seizure model. These findings identify a novel mechanism of circadian regulation and have therapeutic implications for drugs targeted to the central nervous system.

Intercellular junctions in the central nervous system of insects

1977 ◽  
Vol 26 (1) ◽  
pp. 175-199
Author(s):  
N.J. Lane ◽  
H.L. Skaer ◽  
L.S. Swales
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Gap Junctions ◽  
Tight Junctions ◽  
Blood Brain Barrier ◽  
Intercellular Junctions ◽  
Brain Barrier ◽  
Insect Species ◽  
Blood Brain ◽  
The Central Nervous System

The intercellular junctional complexes in the central nervous system (CNS) from a variety of insect species have been examined by thin-sectioning and freeze-fracturing techniques. Of particular concern has been the fine-structural basis of the blood-brain barrier observed to be present in the outer perineurial layer around the avascular insect CNS. The basis of this has been found in the form of tight junctions (zonulae occludentes) present both in sections and in replicas of the perineurium. In the latter, they appear as one or two simple linear ridges, lying parallel to the outer surface, which occasionally display overlapping. The complex geometry of the interdigitating perineurial cells apparently permits such a relatively simple series of ridges to function as a barrier, since tracers are found not to penetrate beyond this level into the underlying nervous tissue. Such evidence is supported by microprobe X-ray analysis of lanthanum-incubated tissues, the perineurium compared with the glia-ensheathed axons showing the presence and absence of lanthanum, respectively. Possible physiological mechanisms that could operate ‘in vitro’ to maintain the blood-brain barrier are also considered. Other intercellular junctions such as desmosomes, septate junctions and gap junctions are found in the perineurial layer too, the last exhibiting EF particle plaques and PF pits. Glia-glia junctions also occur in some insect species; they include desmosomes, inverted gap junctions and occasional tight junctions. Septate, gap and tight junctions are also found on the membranes of tracheoles penetrating the CNS. Short, ridge-like elaborations and other particle arrays are found on the PF on the axon surfaces and the significance of these structures is discussed.

scholarly journals A circadian clock regulates efflux by the blood-brain barrier in mice and human cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shirley L. Zhang ◽  
Nicholas F. Lahens ◽  
Zhifeng Yue ◽  
Denice M. Arnold ◽  
Peter P. Pakstis ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Blood Brain Barrier ◽  
Active Phase ◽  
Brain Barrier ◽  
Microvascular Endothelial Cell ◽  
Circadian Regulation ◽  
Neural Function ◽  
Regulation Of Transcription ◽  
Intracellular Magnesium ◽  
Blood Brain

AbstractThe blood-brain barrier (BBB) is critical for neural function. We report here circadian regulation of the BBB in mammals. Efflux of xenobiotics by the BBB oscillates in mice, with highest levels during the active phase and lowest during the resting phase. This oscillation is abrogated in circadian clock mutants. To elucidate mechanisms of circadian regulation, we profiled the transcriptome of brain endothelial cells; interestingly, we detected limited circadian regulation of transcription, with no evident oscillations in efflux transporters. We recapitulated the cycling of xenobiotic efflux using a human microvascular endothelial cell line to find that the molecular clock drives cycling of intracellular magnesium through transcriptional regulation of TRPM7, which appears to contribute to the rhythm in efflux. Our findings suggest that considering circadian regulation may be important when therapeutically targeting efflux transporter substrates to the CNS.

scholarly journals Can Natural Products Exert Neuroprotection without Crossing the Blood–Brain Barrier?

2021 ◽  
Vol 22 (7) ◽  
pp. 3356
Author(s):  
Manon Leclerc ◽  
Stéphanie Dudonné ◽  
Frédéric Calon
Keyword(s):  
Natural Products ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Brain Diseases ◽  
Omega 3 ◽  
Indirect Pathway ◽  
Brain Functions ◽  
Blood Brain ◽  
The Central Nervous System ◽  
Peripheral Metabolism

The scope of evidence on the neuroprotective impact of natural products has been greatly extended in recent years. However, a key question that remains to be answered is whether natural products act directly on targets located in the central nervous system (CNS), or whether they act indirectly through other mechanisms in the periphery. While molecules utilized for brain diseases are typically bestowed with a capacity to cross the blood–brain barrier, it has been recently uncovered that peripheral metabolism impacts brain functions, including cognition. The gut–microbiota–brain axis is receiving increasing attention as another indirect pathway for orally administered compounds to act on the CNS. In this review, we will briefly explore these possibilities focusing on two classes of natural products: omega-3 polyunsaturated fatty acids (n-3 PUFAs) from marine sources and polyphenols from plants. The former will be used as an example of a natural product with relatively high brain bioavailability but with tightly regulated transport and metabolism, and the latter as an example of natural compounds with low brain bioavailability, yet with a growing amount of preclinical and clinical evidence of efficacy. In conclusion, it is proposed that bioavailability data should be sought early in the development of natural products to help identifying relevant mechanisms and potential impact on prevalent CNS disorders, such as Alzheimer’s disease.

scholarly journals Dual Roles of Astrocyte-Derived Factors in Regulation of Blood-Brain Barrier Function after Brain Damage

2019 ◽  
Vol 20 (3) ◽  
pp. 571 ◽  
Author(s):  
Shotaro Michinaga ◽  
Yutaka Koyama
Keyword(s):  
Brain Damage ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Blood Brain ◽  
Secondary Damage ◽  
The Central Nervous System ◽  
Bbb Permeability ◽  
Novel Therapeutic Strategies ◽  
Glial Derived Neurotrophic Factor ◽  
Endothelial Growth Factors

The blood-brain barrier (BBB) is a major functional barrier in the central nervous system (CNS), and inhibits the extravasation of intravascular contents and transports various essential nutrients between the blood and the brain. After brain damage by traumatic brain injury, cerebral ischemia and several other CNS disorders, the functions of the BBB are disrupted, resulting in severe secondary damage including brain edema and inflammatory injury. Therefore, BBB protection and recovery are considered novel therapeutic strategies for reducing brain damage. Emerging evidence suggests key roles of astrocyte-derived factors in BBB disruption and recovery after brain damage. The astrocyte-derived vascular permeability factors include vascular endothelial growth factors, matrix metalloproteinases, nitric oxide, glutamate and endothelin-1, which enhance BBB permeability leading to BBB disruption. By contrast, the astrocyte-derived protective factors include angiopoietin-1, sonic hedgehog, glial-derived neurotrophic factor, retinoic acid and insulin-like growth factor-1 and apolipoprotein E which attenuate BBB permeability resulting in recovery of BBB function. In this review, the roles of these astrocyte-derived factors in BBB function are summarized, and their significance as therapeutic targets for BBB protection and recovery after brain damage are discussed.

scholarly journals Slowly Changing Bioelectric Potentials Associated With the Blood-Brain Barrier

1958 ◽  
Vol 195 (1) ◽  
pp. 7-22 ◽  
Author(s):  
Robert D. Tschirgi ◽  
J. Langdon Taylor
Keyword(s):  
Cerebral Cortex ◽  
Blood Brain Barrier ◽  
Interstitial Fluid ◽  
Brain Barrier ◽  
Membrane Diffusion ◽  
Arterial Blood ◽  
Blood Ph ◽  
Blood Brain ◽  
The Central Nervous System ◽  
Bioelectric Potentials

A slowly changing bioelectric potential difference (P.D.) is measured in rats, rabbits, cats and dogs between various regions of the central nervous system (CNS) and the blood within the jugular vein. It is shown that the CNS-blood P.D. is very sensitive to alterations in alveolar CO2 tension, but this relationship is dependent upon the H+ concentration rather than CO2 per se. Whereas increasing intravenous H+ concentration increases CNS positivity, topical application of acid solutions directly to the cerebral cortex decreases CNS positivity. The same relationship is found for intravenous and topical K+. Anoxia and circulatory failure produce CNS negative deflections, often exceeding 15 mv, which do not return to zero for over 24 hours after death. Simultaneous measurements of arterial blood pH, cerebral cortex pH and CNS-blood P.D. reveal the following relationship among these variables: ΔP.D. = κ Δ log10 [H+]a/[H+]i where [H+]a is the H+ concentration of the arterial blood and [H+]i is the H+ concentration of the CNS interstitial fluid. For the CNS-blood P.D. between cerebral cortex and jugular blood of rabbits and rats, κ is found to be 29 ± 5. These results are interpreted as indicating a source of emf across the pan-vascular blood-brain barrier which resembles a membrane diffusion potential. The blood-brain barrier is postulated to be more permeable to H+ and K+ than to anions and other cations.

Sign in / Sign up

Export Citation Format

Share Document