1606-P: Effect of Changes in Dark/Light Cycle on Physiological Homeostasis as a Confounding Prelude to Diabetes in Fischer 334 Animal Model

Diabetes ◽  
2020 ◽  
Vol 69 (Supplement 1) ◽  
pp. 1606-P
Author(s):  
BALANEHRU SUBRAMANIAN ◽  
GANAPATHY RAMAKRISHNAN ◽  
PANNERSELVAM TAMILMARAN ◽  
BALAKRISHNAN SUNDARAKRISHNAN ◽  
KRISHNA SESHADRI
Keyword(s):  
Animal Model ◽  
Light Cycle ◽  
Dark Light ◽  
Physiological Homeostasis

Vigilance States: Central Neural Pathways, Neurotransmitters and Neurohormones

2019 ◽  
Vol 19 (1) ◽  
pp. 26-37 ◽  
Author(s):  
Michele Iovino ◽  
Tullio Messana ◽  
Giovanni De Pergola ◽  
Emanuela Iovino ◽  
Edoardo Guastamacchia ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Neural Pathways ◽  
Light Cycle ◽  
Behavioral State ◽  
State Control ◽  
Dark Light ◽  
Concentration Of Ions ◽  
Brainstem Nuclei ◽  
Reticular Activating System ◽  
Plasmatic Concentration

Background and Objective: The sleep-wake cycle is characterized by a circadian rhythm involving neurotransmitters and neurohormones that are released from brainstem nuclei and hypothalamus. The aim of this review is to analyze the role played by central neural pathways, neurotransmitters and neurohormones in the regulation of vigilance states.Method:We analyzed the literature identifying relevant articles dealing with central neural pathways, neurotransmitters and neurohormones involved in the control of wakefulness and sleep.Results:The reticular activating system is the key center in the control of the states of wakefulness and sleep via alertness and hypnogenic centers. Neurotransmitters and neurohormones interplay during the dark-light cycle in order to maintain a normal plasmatic concentration of ions, proteins and peripheral hormones, and behavioral state control.Conclusion:An updated description of pathways, neurotransmitters and neurohormones involved in the regulation of vigilance states has been depicted.

scholarly journals Impact of Inorganic Carbon Availability on Microcystin Production by Microcystis aeruginosa PCC 7806

2007 ◽  
Vol 73 (21) ◽  
pp. 6994-7002 ◽  
Author(s):  
Sabine J�hnichen ◽  
Tilo Ihle ◽  
Thomas Petzoldt ◽  
J�rgen Benndorf
Keyword(s):  
Microcystis Aeruginosa ◽  
Type Strain ◽  
Inorganic Carbon ◽  
Wild Type Strain ◽  
Light Cycle ◽  
Variable Fluorescence ◽  
Wild Type ◽  
Dark Light ◽  
Sodium Dependent ◽  
The Impact

ABSTRACT Batch culture experiments with the cyanobacterium Microcystis aeruginosa PCC 7806 were performed in order to test the hypothesis that microcystins (MCYSTs) are produced in response to a relative deficiency of intracellular inorganic carbon (Ci,i). In the first experiment, MCYST production was studied under increased Ci,i deficiency conditions, achieved by restricting sodium-dependent bicarbonate uptake through replacement of sodium bicarbonate in the medium with its potassium analog. The same experimental approach was used in a second experiment to compare the response of the wild-type strain M. aeruginosa PCC 7806 with its mcyB mutant, which lacks the ability to produce MCYSTs. In a third experiment, the impact of varying the Ci,i status on MCYST production was examined without suppressing the sodium-dependent bicarbonate transporter; instead, a detailed investigation of a dark-light cycle was performed. In all experiments, a relative Ci,i deficiency was indicated by an elevated variable fluorescence signal and led to enhanced phycocyanin cell quotas. Higher MCYST cell quotas (in the first and third experiments) and increased total (intracellular plus extracellular) MCYST production (in the first experiment) were detected with increased Ci,i deficiency. Furthermore, the MCYST-producing wild-type strain and its mcyB mutant showed basically the same response to restrained inorganic carbon uptake, with elevated variable fluorescence and phycocyanin cell quotas with increased Ci,i deficiency. The response of the wild type, however, was distinctly stronger and also included elevated chlorophyll a cell quotas. These differences indicate the limited ability of the mutant to adapt to low-Ci,i conditions. We concluded that MCYSTs may be involved in enhancing the efficiency of the adaptation of the photosynthetic apparatus to fluctuating inorganic carbon conditions in cyanobacterial cells.

scholarly journals Multi Floral Honey Has a Protective Effect against Mammary Cancer Induced by 7,12-Dimethylbenz(a)anthracene in Sprague Dawley Rats

2017 ◽  
Vol 9 (2) ◽  
pp. 196 ◽  
Author(s):  
Hamed R. Takruri ◽  
Maha S. Shomaf ◽  
Saida F. Shnaigat
Keyword(s):  
Protective Effect ◽  
Mammary Cancer ◽  
Histopathological Examination ◽  
Negative Control Group ◽  
Positive Control ◽  
Negative Control ◽  
Control Group ◽  
Light Cycle ◽  
Sprague Dawley ◽  
Dark Light

This research was conducted to study the protective effect of bee honey on the 7,12-dimethylbenz(a)anthracene (DMBA)- induced breast cancer in rat model. The study consisted of three groups: honey group, positive control group (PC), and negative control group (NC) to which the carcinogen was not administered. All rats were fed the diet recommended by the American Institute of Nutrition for growing rats (AIN-93G), with addition of honey (50 g/kg diet) to the honey group. All Rats were fed their diets ad libitum on 12 hours dark/light cycle. At the age of 50 days all rats in the honey and PC groups were gavaged once by the carcinogen DMBA with a dose of 80 mg/kg body Wt. After three weeks of carcinogen administration, rats were palpated weekly to detect any tumor growth. After 18 weeks, all rats were sacrificed. The palpable structures and the mammary glands along with associated lymph nodes were removed and fixed in saline formalin and prepared for histopathological examination. The results revealed that the honey group diet significantly (p < 0.05) reduced the incidence rate of mammary cancer, palpable tumor multiplicity, tumor size and weight compared to the PC group. In conclusion, multi floral honey has a protective effect against DMBA- induced mammary cancer in the initiation, promotion, and progression stages of DMBA-induced mammary carcinogenesis. However, further research is needed to reveal the mechanisms that might have contributed to the preventive effect of honey against mammary cancer.

Both orexin receptors are expressed in rat ovaries and fluctuate with the estrous cycle: effects of orexin receptor antagonists on gonadotropins and ovulation

2007 ◽  
Vol 293 (4) ◽  
pp. E977-E985 ◽  
Author(s):  
Patricia Silveyra ◽  
Victoria Lux-Lantos ◽  
Carlos Libertun
Keyword(s):  
Structural Changes ◽  
Corpora Lutea ◽  
Light Cycle ◽  
Sprague Dawley ◽  
Receptor Antagonists ◽  
Dark Light ◽  
Orexin Receptors ◽  
Sprague Dawley Rats ◽  
The Central Nervous System ◽  
First Time

Orexins are peptides controlling feeding, sleep, and neuroendocrine functions. They are synthesized by the hypothalamus with projections throughout the brain. Orexins and their orexin 1 (OX1) and orexin 2 receptors (OX2) are present outside the central nervous system. Here the expression of preproorexin (PPO), OX1, and OX2 was studied in rat ovaries. PPO, OX1, and OX2 were determined by quantitative real-time RT-PCR in ovaries of cycling Sprague-Dawley rats on all days of the cycle. Serum hormones and food consumption were determined. Ovarian OX1 and OX2 expression was then studied after ovulation blockade with Cetrorelix or Nembutal. Finally, proestrous rats were treated at 1400 and 1900 with a selective OX1 antagonist (SB-334867-A) and/or a selective OX2 antagonist (JNJ-10397049), and hormone levels, ovulation, and ovarian histology were studied. Both receptors' expression increased in the ovary between 1700 and 2300 of proestrus exclusively, in coincidence with hormone peaks, but not with the dark-light cycle or food intake. PPO was not detected. Cetrorelix or Nembutal prevented the increases of OX1 and OX2 while blunting gonadotropin peaks. SB-334867-A and JNJ-10397049, alone or combined, decreased serum gonadotropins and reduced ova number the following morning; ovaries showed a bloody (hyperemic and/or hemorrhagic) reaction with more preovulatory follicles and less corpora lutea. Here we demonstrate for the first time an increased ovarian expression of both OX1 and OX2, only during proestrous afternoon, and its hormone dependence but not dependence on the dark-light cycle. Two new receptor antagonists reduced proestrous gonadotropins and/or ova number while producing ovarian structural changes.

Circadian variations of adenosine and of its metabolism. Could adenosine be a molecular oscillator for circadian rhythms?

1995 ◽  
Vol 73 (3) ◽  
pp. 339-355 ◽  
Author(s):  
Victoria Chagoya de Sánchez
Keyword(s):  
Membrane Structure ◽  
Adenosine Kinase ◽  
Light Cycle ◽  
Circadian Variations ◽  
Dark Light ◽  
Metabolic Pattern ◽  
Molecular Oscillator ◽  
Adenosine Concentration ◽  
Membrane Structure And Function ◽  
Different Tissues

The present review describes the biological implications of the periodic changes of adenosine concentrations in different tissues of the rat. Adenosine is a purine molecule that could have been formed in the prebiotic chemical evolution and has been preserved. The rhythmicity of this molecule, as well as its metabolism and even the presence of specific receptors, suggests a regulatory role in eukaryotic cells and in multicellular organisms. Adenosine may be considered a chemical messenger and its action could take place at the level of the same cell (autocrine), the same tissue (paracrine), or on separate organs (endocrine). Exploration of the circadian variations of adenosine was planned considering the liver as an important tissue for purine formation, the blood as a vehicle among tissues, and the brain as the possible acceptor for hepatic adenosine or its metabolites. The rats used in these studies were adapted to a dark–light cycle of 12 h with an unrestrained feeding and drinking schedule. The metabolic control of adenosine concentration in the different tissues studied through the 24-h cycle is related to the activity of adenosine-metabolizing enzymes: 5′-nucleotidase adenosine deaminase, adenosine kinase, and S-adenosylhomocysteine hydrolase. Some possibilities of the factors modulating the activity of these enzymes are commented upon. The multiphysiological action of adenosine could be mediated by several actions: (i) by interaction with extracellular and intracellular receptors and (ii) through its metabolism modulating the methylation pathway, possibly inducing physiological lipoperoxidation, or participating in the energetic homeostasis of the cell. The physiological meaning of the circadian variations of adenosine and its metabolism was focused on: maintenance of the energetic homeostasis of the tissues, modulation of membrane structure and function, regulation of fasting and feeding metabolic pattern, and its participation in the sleep–wake cycle. From these considerations, we suggest that adenosine could be a molecular oscillator involved in the circadian pattern of biological activity in the rat.Key words: adenosine, circadian rhythm energy, membrane structure, sleep–wake cycle.

scholarly journals Major oscillations in spontaneous home-cage activity with an infraradian periodicity in C57Bl/6 mice housed under constant conditions

2020 ◽  
Author(s):  
K. Pernold ◽  
E. Rullman ◽  
B. Ulfhake
Keyword(s):  
Spontaneous Activity ◽  
Feeding Behaviour ◽  
Home Cage ◽  
Light Cycle ◽  
Dark Light ◽  
Cage Activity ◽  
Free Running ◽  
The Mean ◽  
Home Cage Activity

AbstractUsing 14-20 months of cumulative 24/7 home-cage activity recorded with a non-intrusive technique and a data driven analytical approach, we here provide evidence for the existence of a circannual oscillation (1-2 SD of the mean, on average 65% higher during peak of highs than lows; P=7E-50) in spontaneous activity of male and female C57BL/6 mice held under constant barrier conditions (dark-light cycle 12/12 h (DL), temperature 21±1°C, humidity 40-60%). The periodicity of the season-like oscillation is in the range of 2-4 months (on average 97 days across cohorts of cages) and off-sets also responses to environmental stimuli but does not significantly alter the preference for activity during the dark hours of this nocturnal mouse strain (P=0.11 difference between highs and lows).The significance of this hitherto not recognized slow rhythmic alteration in spontaneous activity is further substantiated by its co-variation with the feeding behaviour of the mice. The absence of coordination within and between cohorts of cages or synchronization to the seasons of the year, suggests that the oscillation of in-cage activity and behavioural responses is generated by a free-running intrinsic oscillator devoid of synchronization with an out-of-cage environmental time-keeper. Since the variation over time has such a magnitude and correlate with the feeding behaviour it is likely that it will impact a range of long term experiments conducted on laboratory mice if left unrecognized.

scholarly journals Sleep/Wake Behavior and EEG Signatures of the TgF344-AD Rat Model at the Prodromal Stage

2020 ◽  
Vol 21 (23) ◽  
pp. 9290
Author(s):  
Matthias Kreuzer ◽  
Glenda L. Keating ◽  
Thomas Fenzl ◽  
Lorenz Härtner ◽  
Christopher G. Sinon ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Eye Movement ◽  
Rat Model ◽  
Protein Modification ◽  
Light Cycle ◽  
Rapid Eye Movement ◽  
Rapid Eye Movement Sleep ◽  
Dark Light ◽  
Eeg Features

Transgenic modification of the two most common genes (APPsw, PS1ΔE9) related to familial Alzheimer’s disease (AD) in rats has produced a rodent model that develops pathognomonic signs of AD without genetic tau-protein modification. We used 17-month-old AD rats (n = 8) and age-matched controls (AC, n = 7) to evaluate differences in sleep behavior and EEG features during wakefulness (WAKE), non-rapid eye movement sleep (NREM), and rapid eye movement sleep (REM) over 24-h EEG recording (12:12h dark–light cycle). We discovered that AD rats had more sleep–wake transitions and an increased probability of shorter REM and NREM bouts. AD rats also expressed a more uniform distribution of the relative spectral power. Through analysis of information content in the EEG using entropy of difference, AD animals demonstrated less EEG information during WAKE, but more information during NREM. This seems to indicate a limited range of changes in EEG activity that could be caused by an AD-induced change in inhibitory network function as reflected by increased GABAAR-β2 expression but no increase in GAD-67 in AD animals. In conclusion, this transgenic rat model of Alzheimer’s disease demonstrates less obvious EEG features of WAKE during wakefulness and less canonical features of sleep during sleep.

Free-feeding patterns of rats in response to changes in environmental temperature

1976 ◽  
Vol 231 (4) ◽  
pp. 1220-1224 ◽  
Author(s):  
PM Leung ◽  
BA Horwitz
Keyword(s):  
Cold Exposure ◽  
Energy Demand ◽  
Meal Size ◽  
Meal Frequency ◽  
Sudden Increase ◽  
Light Cycle ◽  
Sprague Dawley ◽  
Feeding Patterns ◽  
Adult Rats ◽  
Dark Light

Four adult Sprague-Dawley rats (430-450 g), maintained on a 12:12 h dark/light cycle and 15% casein diet, were exposed to cold (5 degrees C) for 77 days and then transferred back to 24 degrees C. Throughout thisperiod, the feeding patterns of the rats were measured with recording balances. Cold exposure caused an immediate reduction in nocturnal meal frequency that remained low during the cold exposure. In contrast, diurnal meal frequency was unaltered. Average nocturnal meal size, which did not significantly increase before 8 days of cold, reached a plateau in 2 wk, whereas the average diurnal meal size did not significantly change until late in the exposure period. "Warm" (24 degrees C) reentry elicited an abrupt increase in nocturnal meal frequency and a reduction in average nocturnal as well as diurnal meal size. It thus appears that even in the face of a sudden increase in energy expenditure resulting from cold exposure, adult rats do not immediately adjust their daily food intake. On the other hand, the adaptive hyperphagic response occurring after cold acclimation is abolished when the energy demand is eliminated, i.e., when the animals are removed from the cold.

scholarly journals The Effect on Rat Thymocytes of the Simultaneous In Vivo Exposure to 50-Hz Electric and Magnetic Field and to Continuous Light

2004 ◽  
Vol 4 ◽  
pp. 91-99 ◽  
Author(s):  
Daniela Quaglino ◽  
Miriam Capri ◽  
Luigi Zecca ◽  
Claudio Franceschi ◽  
Ivonne P. Ronchetti
Keyword(s):  
Light Exposure ◽  
Low Frequency ◽  
Continuous Light ◽  
Light Cycle ◽  
Sprague Dawley ◽  
Dark Light ◽  
Sprague Dawley Rats ◽  
Electric And Magnetic Fields

Thymus plays an important role in the immune system and can be modulated by numerous environmental factors, including electromagnetic fields (EMF). The present study has been undertaken with the aim to investigate the role of long-term exposure to extremely low frequency electric and magnetic fields (ELF-EMF) on thymocytes of rats housed in a regular dark/light cycle or under continuous light. Male Sprague-Dawley rats, 2 months old, were exposed or sham exposed for 8 months to 50-Hz sinusoidal EMF at two levels of field strength (1 kV/m, 5 μT and 5 kV/m, 100 μT, respectively). Thymus from adult animals exhibits signs of gradual atrophy mainly due to collagen deposition and fat substitution. This physiological involution may be accelerated by continuous light exposure that induces a massive death of thymocytes. The concurrent exposure to continuous light and to ELF-EMF did not change significantly the rate of mitoses compared to sham-exposed rats, whereas the amount of cell death was significantly increased, also in comparison with animals exposed to EMF in a 12-h dark-light cycle. In conclusion, long-term exposure to ELF-EMF, in animals housed under continuous light, may reinforce the alterations due to a photic stress, suggesting that,in vivo, stress and ELF-EMF exposure can act in synergy determining a more rapid involution of the thymus and might be responsible for an increased susceptibility to the potentially hazardous effects of ELF-EMF.

Diurnal and seasonal changes in sympathetic signal transduction in cardiac ventricles of European hamsters

1996 ◽  
Vol 270 (1) ◽  
pp. R304-R309 ◽  
Author(s):  
K. Pleschka ◽  
A. Heinrich ◽  
K. Witte ◽  
B. Lemmer
Keyword(s):  
Adenylyl Cyclase ◽  
Rank Order ◽  
Constant Darkness ◽  
Receptor Subtypes ◽  
Dark Phase ◽  
Light Cycle ◽  
Dark Light ◽  
Cardiac Ventricles ◽  
Beta 2 ◽  
The Relationship

This investigation of the relationship between cardiac beta-adrenoceptors and adenosine 3',5'-cyclic monophosphate (cAMP) formation in cardiac ventricles of the nocturnally active European hamster both during euthermia under a 12:12-h dark-light cycle and during hibernation under constant-darkness conditions showed that neither the densities, affinities, nor distribution of the beta 1- and beta 2-receptor subtypes differed between the dark phase, light phase, and hibernation. Basal formation of cAMP by the cardiac adenylyl cyclase of euthermic hamsters was higher in ventricles obtained at night [core temperature (Tcore) = 37.8 degrees C] than in ventricles obtained during the day (Tcore = 36.4 degrees C). Basal formation of cAMP was also significantly lower in hibernating hamsters (Tcore = 7.0 degrees C) than in euthermic hamsters. When adenylyl cyclase activity was stimulated by isoprenaline, guanylylimidodiphosphate [Gpp(NH)p], or forskolin, the rank order of potency was the same in euthermic hamsters and hibernating hamsters: isoprenaline < Gpp(NH)p < forskolin. Functional competition curves indicated that in the euthermic hamsters beta 1-receptors were responsible for 67% of the response to isoprenaline at night and 62% of the response during the day. In hibernating hamsters, in contrast, most of the response to isoprenaline (58%) was mediated via beta 2-receptors. This shift in the relative importance of the receptor subtypes may facilitate arousal from hibernation by making the heart more sensitive to circulating epinephrine.

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