Browsing by Subject "Circadian"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Circadian variability of body temperature responses to methamphetamine
    (American Physiological Society, 2018-01) Behrouzvaziri, Abolhassan; Zaretskaia, Maria V.; Rusyniak, Daniel E.; Zaretsky, Dmitry V.; Molkov, Yaroslav I.; Mathematical Sciences, School of Science
    Vital parameters of living organisms exhibit circadian rhythmicity. Although rats are nocturnal animals, most of the studies involving rats are performed during the day. The objective of this study was to examine the circadian variability of the body temperature responses to methamphetamine. Body temperature was recorded in male Sprague-Dawley rats that received intraperitoneal injections of methamphetamine (Meth, 1 or 5 mg/kg) or saline at 10 AM or at 10 PM. The baseline body temperature at night was 0.8°C higher than during the day. Both during the day and at night, 1 mg/kg of Meth induced monophasic hyperthermia. However, the maximal temperature increase at night was 50% smaller than during the daytime. Injection of 5 mg/kg of Meth during the daytime caused a delayed hyperthermic response. In contrast, the same dose at night produced responses with a tendency toward a decrease of body temperature. Using mathematical modeling, we previously showed that the complex dose dependence of the daytime temperature responses to Meth results from an interplay between inhibitory and excitatory drives. In this study, using our model, we explain the suppression of the hyperthermia in response to Meth at night. First, we found that the baseline activity of the excitatory drive is greater at night. It appears partially saturated and thus is additionally activated by Meth to a lesser extent. Therefore, the excitatory component causes less hyperthermia or becomes overpowered by the inhibitory drive in response to the higher dose. Second, at night the injection of Meth results in reduction of the equilibrium body temperature, leading to gradual cooling counteracting hyperthermia.
  • Thumbnail Image
    Item
    Ethanol consumption in mice: relationships with circadian period and entrainment
    (Elsevier, 2011-03) Trujillo, Jennifer L.; Do, David T.; Grahame, Nicholas J.; Roberts, Amanda J.; Gorman, Michael R.; Department of Psychology, School of Science
    A functional connection between the circadian timing system and alcohol consumption is suggested by multiple lines of converging evidence. Ethanol consumption perturbs physiological rhythms in hormone secretion, sleep and body temperature, and conversely, genetic and environmental perturbations of the circadian system can alter alcohol intake. A fundamental property of the circadian pacemaker, the endogenous period of its cycle under free-running conditions, was previously shown to differ between selectively bred High- (HAP) and Low- (LAP) Alcohol Preferring replicate 1 mice. To test whether there is a causal relationship between circadian period and ethanol intake, we induced experimental, rather than genetic, variations in free-running period. Male inbred C57Bl/6J mice and replicate 2 male and female HAP2 and LAP2 mice were entrained to light:dark cycles of 26 h or 22 h or remained in a standard 24 h cycle. Upon discontinuation of the light:dark cycle, experimental animals exhibited longer and shorter free-running periods, respectively. Despite robust effects on circadian period and clear circadian rhythms in drinking, these manipulations failed to alter the daily ethanol intake of the inbred strain or selected lines. Likewise, driving the circadian system at long and short periods produced no change in alcohol intake. In contrast with replicate 1 HAP and LAP lines, there was no difference in free-running period between ethanol naïve HAP2 and LAP2 mice. HAP2 mice, however, were significantly more active than LAP2 mice as measured by general home-cage movement and wheel running, a motivated behavior implicating a selection effect on reward systems. Despite a marked circadian regulation of drinking behavior, the free-running and entrained period of the circadian clock does not determine daily ethanol intake.
  • Thumbnail Image
    Item
    Loss of Diurnal Oscillatory Rhythms in Gut Microbiota Correlates with Changes in Circulating Metabolites in Type 2 Diabetic db/db Mice
    (MDPI, 2019-09-29) Beli, Eleni; Prabakaran, Samantha; Krishnan, Preethi; Evans-Molina, Carmella; Grant, Maria B.; Pediatrics, School of Medicine
    Our hypothesis is that diabetes leads to loss of diurnal oscillatory rhythms in gut microbiota altering circulating metabolites. We performed an observational study where we compared diurnal changes of the gut microbiota with temporal changes of plasma metabolites. Metadata analysis from bacterial DNA from fecal pellets collected from 10-month old control (db/m) and type 2 diabetic (db/db) mice every 4 h for a 24-h period was used for prediction analysis. Blood plasma was collected at a day and night time points and was used for untargeted global metabolomic analysis. Feeding and activity behaviors were recorded. Our results show that while diabetic mice exhibited feeding and activity behavior similar to control mice, they exhibited a loss of diurnal oscillations in bacteria of the genus Akkermansia, Bifidobacterium, Allobaculum, Oscillospira and a phase shift in the oscillations of g.Prevotella, proteobacteria, and actinobacteria. Analysis of the circulating metabolites showed alterations in the diurnal pattern of metabolic pathways where bacteria have been implicated, such as the histidine, betaine, and methionine/cysteine pathway, mitochondrial function and the urea cycle. Functional analysis of the differential microbes revealed that during the day, when mice are asleep, the microbes of diabetic mice were enriched in processing carbon and pyruvate metabolic pathways instead of xenobiotic degradation as was observed for control mice. Altogether, our study suggests that diabetes led to loss of rhythmic oscillations of many gut microbiota with possible implications for temporal regulation of host metabolic pathways.
  • Thumbnail Image
    Item
    Strategies and foundations for scientific discovery in longitudinal studies of bipolar disorder
    (Wiley, 2022) McInnis, Melvin G.; Andreassen, Ole A.; Andreazza, Ana C.; Alon, Uri; Berk, Michael; Brister, Teri; Burdick, Katherine E.; Cui, Donghong; Frye, Mark; Leboyer, Marion; Mitchell, Philip B.; Merikangas, Kathleen; Nierenberg, Andrew A.; Nurnberger, John I.; Pham, Daniel; Vieta, Eduard; Yatham, Lakshmi N.; Young, Allan H.; Psychiatry, School of Medicine
    Bipolar disorder (BD) is a complex and dynamic condition with a typical onset in late adolescence or early adulthood followed by an episodic course with intervening periods of subthreshold symptoms or euthymia. It is complicated by the accumulation of comorbid medical and psychiatric disorders. The etiology of BD remains unknown and no reliable biological markers have yet been identified. This is likely due to lack of comprehensive ontological framework and, most importantly, the fact that most studies have been based on small nonrepresentative clinical samples with cross‐sectional designs. We propose to establish large, global longitudinal cohorts of BD studied consistently in a multidimensional and multidisciplinary manner to determine etiology and help improve treatment. Herein we propose collection of a broad range of data that reflect the heterogenic phenotypic manifestations of BD that include dimensional and categorical measures of mood, neurocognitive, personality, behavior, sleep and circadian, life‐story, and outcomes domains. In combination with genetic and biological information such an approach promotes the integrating and harmonizing of data within and across current ontology systems while supporting a paradigm shift that will facilitate discovery and become the basis for novel hypotheses.
  • Thumbnail Image
    Item
    Tumor Necrosis Factor Alpha (TNF-α) Disrupts Kir4.1 Channel Expression Resulting in Müller Cell Dysfunction in the RetinaDiurnal Rhythm of Kir4.1 in the Retina
    (ARVO, 2017-05-01) Hassan, Iraj; Luo, Qianyi; Majumdar, Sreeparna; Dominguez, James M.; Busik, Julia V.; Bhatwadekar, Ashay D.; Department of Ophthalmology, IU School of Medicine
    Purpose: Diabetic patients often are affected by vision problems. We previously identified diabetic retinopathy (DR) as a disease of clock gene dysregulation. TNF-α, a proinflammatory cytokine, is known to be elevated in DR. Müller cells maintain retinal water homeostasis and K+ concentration via Kir4.1 channels. Notably, Kir4.1 expression is reduced in diabetes; however, the interplay of TNF-α, Kir4.1, and clock genes in Müller cells remains unknown. We hypothesize that the Kir4.1 in Müller cells is under clock regulation, and increase in TNF-α is detrimental to Kir4.1. Methods: Long-Evans rats were made diabetic using streptozotocin (STZ). Retinal Kir4.1 expression was determined at different time intervals. Rat Müller (rMC-1) cells were transfected with siRNA for Per2 or Bmal1 and in parallel treated with TNF-α (5–5000 pM) to determine Kir4.1 expression. Results: Kir4.1 expression exhibited a diurnal rhythm in the retina; however, with STZ-induced diabetes, Kir4.1 was reduced overall. Kir4.1 rhythm was maintained in vitro in clock synchronized rMC-1 cells. Clock gene siRNA-treated rMC-1 exhibited a decrease in Kir4.1 expression. TNF-α treatment of rMCs lead to a profound decrease in Kir4.1 due to reduced colocalization of Kir4.1 channels with synapse-associated protein (SAP97) and disorganization of the actin cytoskeleton. Conclusions: Our findings demonstrate that Kir4.1 channels possess a diurnal rhythm, and this rhythm is dampened with diabetes, thereby suggesting that the increase in TNF-α is detrimental to normal Kir4.1 rhythm and expression.