Astrocytes as essential time‐keepers of the central pacemaker

Glia ◽  
2021 ◽  
Author(s):  
Mariana Astiz ◽  
Lina Maria Delgado‐García ◽  
Laura López‐Mascaraque
Keyword(s):  
Central Pacemaker

scholarly journals Circadian Rhythms, the Mesolimbic Dopaminergic Circuit, and Drug Addiction

2007 ◽  
Vol 7 ◽  
pp. 194-202 ◽  
Author(s):  
Colleen A. McClung
Keyword(s):  
Circadian Rhythms ◽  
Drug Addiction ◽  
Molecular Mechanisms ◽  
Dopaminergic System ◽  
Treatment Options ◽  
Drug Induced ◽  
Circadian Genes ◽  
Dopaminergic Transmission ◽  
Central Pacemaker

Drug addiction is a devastating disease that affects millions of individuals worldwide. Through better understanding of the genetic variations that create a vulnerability for addiction and the molecular mechanisms that underlie the progression of addiction, better treatment options can be created for those that suffer from this condition. Recent studies point to a link between abnormal or disrupted circadian rhythms and the development of addiction. In addition, studies suggest a role for specific genes that make up the molecular clock in the regulation of drug sensitivity, sensitization, and reward. The influence of circadian genes and rhythms on drug-induced behaviors may be mediated through the mesolimbic dopaminergic system. This system has long been implicated in the development of addiction, and recent evidence supports a regulatory role for the brain's central pacemaker and circadian gene expression in the regulation of dopaminergic transmission. This review highlights the association between circadian genes and drug addiction, and the possible role of the mesolimbic dopaminergic system in this association.

Physiological Activity and Artefacts in Epileptic Brain in Subdural EEG

2018 ◽  
pp. 84-97
Author(s):  
Beate Diehl ◽  
Catherine A. Scott
Keyword(s):  
Motor Cortex ◽  
Brain Region ◽  
Physiological Activity ◽  
Brain Oscillations ◽  
Intracranial Eeg ◽  
Scalp Eeg ◽  
Focal Pattern ◽  
Mu Rhythms ◽  
Eeg Recordings ◽  
Central Pacemaker

‘Physiological activity and artefacts in epileptic brain in subdural EEG’ reviews intracranial appearances of physiological brain rhythms in each brain region, many of which are also seen on scalp EEG. The alpha rhythm has been described as originating from multiple occipital and extra-occipital cortical generators variously overlapping and influencing each other, probably under the relative control of a central pacemaker. Another more focal pattern has been described in intracranial EEG recordings in the calcarine region, with a third rhythm arising in midtemporal regions, not detectable in scalp EEG, with a frequency in the alpha or theta range. Lambda waves, sleep structures, and mu rhythms over motor cortex can also be detected on subdural electrodes. On a region-by-region basis, intracranial EEG appearances are summarized, including brain oscillations in hippocampus and motor cortex and their modifiers, as well as ongoing rhythms in cingulum. Common sources of physiological and non-physiological artefacts are reviewed.

In vivo pulsatility of pancreatic islet peptides

1986 ◽  
Vol 251 (2) ◽  
pp. E215-E226 ◽  
Author(s):  
J. B. Jaspan ◽  
E. Lever ◽  
K. S. Polonsky ◽  
E. Van Cauter
Keyword(s):  
Spectral Analysis ◽  
Mammalian Species ◽  
Oscillatory Behavior ◽  
Computer Assisted ◽  
C Peptide ◽  
Tightly Coupled ◽  
Underlying Mechanisms ◽  
Central Pacemaker ◽  
Significant Periodicity

In vivo oscillations of pancreatic peptides are recognized in primates. To determine whether such oscillations also occur in other mammalian species and to examine their underlying mechanisms, portal vein levels of insulin, C-peptide, glucagon, somatostatin, pancreatic polypeptide (PP), and glucose were measured simultaneously at 1- or 2-min intervals in nine conscious dogs. For comparison with primates, additional experiments were conducted in baboons and humans. Computer-assisted pulse identification for both raw and smoothed data was performed and spectral estimations calculated after detrending. Concomitance and comovement between the fluctuations of the various peptides and glucose were tested. Prominent pulses at 10- to 14-min intervals were detected most regularly for insulin and glucagon and were frequently reflected in PP and somatostatin levels. Corresponding relative increments in plasma concentration averaged 54% for insulin, 16% for glucagon, 25% for PP, and 24% for somatostatin. Insulin pulses were concomitant with glucagon pulses in 80% of the cases. Pulses of PP were less frequent, although consistently associated with insulin pulses. Somatostatin pulses were less consistently associated with those of other peptides. Peptide oscillations were unrelated to glucose changes. Spectral analysis confirmed these results with peaks in the 10- to 14-min range for all peptides but no significant periodicity for glucose. No consistent delays or advances between the oscillations of the various peptides could be demonstrated. It is speculated that oscillatory behavior in the pancreas may be related to a central pacemaker mechanism, which involves insulin tightly coupled to glucagon, entraining the fluctuations of PP, and, inconsistently, of somatostatin.

scholarly journals Entrainment of peripheral clock genes by cortisol

2012 ◽  
Vol 44 (11) ◽  
pp. 607-621 ◽  
Author(s):  
Panteleimon D. Mavroudis ◽  
Jeremy D. Scheff ◽  
Steve E. Calvano ◽  
Stephen F. Lowry ◽  
Ioannis P. Androulakis
Keyword(s):  
Clock Genes ◽  
Dynamic Regime ◽  
The Body ◽  
Molecular Function ◽  
Frequency Range ◽  
Peripheral Tissues ◽  
Peripheral Clock ◽  
Peripheral Clocks ◽  
Central Pacemaker ◽  
Peripheral Cells

Circadian rhythmicity in mammals is primarily driven by the suprachiasmatic nucleus (SCN), often called the central pacemaker, which converts the photic information of light and dark cycles into neuronal and hormonal signals in the periphery of the body. Cells of peripheral tissues respond to these centrally mediated cues by adjusting their molecular function to optimize organism performance. Numerous systemic cues orchestrate peripheral rhythmicity, such as feeding, body temperature, the autonomic nervous system, and hormones. We propose a semimechanistic model for the entrainment of peripheral clock genes by cortisol as a representative entrainer of peripheral cells. This model demonstrates the importance of entrainer's characteristics in terms of the synchronization and entrainment of peripheral clock genes, and predicts the loss of intercellular synchrony when cortisol moves out of its homeostatic amplitude and frequency range, as has been observed clinically in chronic stress and cancer. The model also predicts a dynamic regime of entrainment, when cortisol has a slightly decreased amplitude rhythm, where individual clock genes remain relatively synchronized among themselves but are phase shifted in relation to the entrainer. The model illustrates how the loss of communication between the SCN and peripheral tissues could result in desynchronization of peripheral clocks.

On the Communication Pathways between the Central Pacemaker and Peripheral Oscillators

2008 ◽  
pp. 126-139 ◽  
Author(s):  
Nicolas Cermakian ◽  
Matthew P. Pando ◽  
Masao Doi ◽  
Luca Cardone ◽  
Irene Yujnovsky ◽  
...  
Keyword(s):  
Peripheral Oscillators ◽  
Central Pacemaker

Noncellular Niche Influences: Nervous System Mediators, Metabolic Mediators, and Hypoxia/Oxidative Stress

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. SCI-26-SCI-26
Author(s):  
Simón Méndez-Ferrer
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Nervous System ◽  
Mesenchymal Stem Cells ◽  
Myeloproliferative Neoplasms ◽  
Sympathetic Nerves ◽  
Leukemic Cells ◽  
Hematopoietic Stem ◽  
Hsc Niche ◽  
Central Pacemaker

Hematopoietic stem cells (HSCs) traffic between bone marrow and circulation, what allows for life-saving clinical transplantation. Our previous work has shown that HSC numbers in blood follow circadian oscillations that are regulated by the central pacemaker in the brain, which reaches bone marrow nestin+ mesenchymal stem cells through peripheral sympathetic nerves. In the perinatal bone marrow, HSC-niche forming mesenchymal stem cells might be different from those that form the skeleton and some of them might be neural crest-derived, like peripheral neurons and supporting glial cells. Thus, tight regulation of the bone marrow stem-cell niche in vertebrates might build upon developmental relationships of its cellular components. We have found recently that cholinergic nerves regulate HSC maintenance, proliferation and migration in divergent niches. We will present unpublished evidence of how both branches of the autonomic nervous system cooperate to regulate HSC maintenance and function in spatially and temporally distinct niches. Moreover, we have shown recently that damage to this regulatory network is essential for the manifestation of myeloproliferative neoplasms. In these diseases, previously thought to be driven solely by mutated HSCs, protecting the HSC niche might represent a novel therapeutic strategy. Patients with myeloproliferative neoplasms have a higher risk of developing acute leukemia. However, at this stage, leukemic cells might be less sensitive to the normal control by the microenvironment and, instead, acute myelogenous leukemic cells might transform the bone marrow niches to support their own survival. We will discuss potential contributions of HSC niches to myeloproliferative neoplasms and MLL-AF9-driven acute myeloid leukemia. Disclosures Off Label Use: Potential use of selective estrogen receptor modulators and beta3-adrenergic agonists in myeloproliferative neoplasms.

scholarly journals Disruption of gene expression rhythms in mice lacking secretory vesicle proteins IA-2 and IA-2β

2012 ◽  
Vol 303 (6) ◽  
pp. E762-E776 ◽  
Author(s):  
Sohan Punia ◽  
Kyle K. Rumery ◽  
Elizabeth A. Yu ◽  
Christopher M. Lambert ◽  
Abner L. Notkins ◽  
...  
Keyword(s):  
Gene Expression ◽  
Secretory Vesicle ◽  
Diurnal Rhythms ◽  
Double Knockout ◽  
Peripheral Tissues ◽  
Oscillatory Function ◽  
Peripheral Oscillators ◽  
Central Pacemaker ◽  
The Impact ◽  
Single Knockout

Insulinoma-associated protein (IA)-2 and IA-2β are transmembrane proteins involved in neurotransmitter secretion. Mice with targeted disruption of both IA-2 and IA-2β (double-knockout, or DKO mice) have numerous endocrine and physiological disruptions, including disruption of circadian and diurnal rhythms. In the present study, we have assessed the impact of disruption of IA-2 and IA-2β on molecular rhythms in the brain and peripheral oscillators. We used in situ hybridization to assess molecular rhythms in the hypothalamic suprachiasmatic nuclei (SCN) of wild-type (WT) and DKO mice. The results indicate significant disruption of molecular rhythmicity in the SCN, which serves as the central pacemaker regulating circadian behavior. We also used quantitative PCR to assess gene expression rhythms in peripheral tissues of DKO, single-knockout, and WT mice. The results indicate significant attenuation of gene expression rhythms in several peripheral tissues of DKO mice but not in either single knockout. To distinguish whether this reduction in rhythmicity reflects defective oscillatory function in peripheral tissues or lack of entrainment of peripheral tissues, animals were injected with dexamethasone daily for 15 days, and then molecular rhythms were assessed throughout the day after discontinuation of injections. Dexamethasone injections improved gene expression rhythms in liver and heart of DKO mice. These results are consistent with the hypothesis that peripheral tissues of DKO mice have a functioning circadian clockwork, but rhythmicity is greatly reduced in the absence of robust, rhythmic physiological signals originating from the SCN. Thus, IA-2 and IA-2β play an important role in the regulation of circadian rhythms, likely through their participation in neurochemical communication among SCN neurons.

scholarly journals Effects of TWIN-OF-EYELESS onClockGene Expression and Central-Pacemaker Neuron Development inDrosophila

2014 ◽  
Vol 29 (3) ◽  
pp. 151-166 ◽  
Author(s):  
Nicholas R.J. Glossop ◽  
Jennet O. Gummadova ◽  
Indrayani Ghangrekar ◽  
Paul E. Hardin ◽  
Graham A. Coutts
Keyword(s):  
Neuron Development ◽  
Pacemaker Neuron ◽  
Central Pacemaker
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