bims-ciryme Biomed News
on Circadian rhythms and metabolism
Issue of 2020‒06‒07
three papers selected by
Gabriela Da Silva Xavier
University of Birmingham

  1. Mol Cell. 2020 Jun 04. pii: S1097-2765(20)30311-7. [Epub ahead of print]78(5): 805-807
      The amplitude of circadian rhythms dampens with age, but Levine et al. (2020) now show that nicotinamide adenine dinucleotide (NAD+) can restore robust circadian gene expression and behavior in aged mice through SIRT1-dependent deacetylation of the core clock protein PER2.
  2. Obesity (Silver Spring). 2020 May 31.
      OBJECTIVE: Epidemiological studies show that shift workers are at increased risk for type 2 diabetes. As modern societies increasingly require shift work, it seems crucial to determine whether there are long-lasting health effects of rotational shifts.METHODS: This study examined the after-effects of 4 weeks of time-restricted feeding (TRF) during the light period (= light-fed) in rats, an animal model for shift work. This study also included a TRF-dark (= dark-fed) control group. The aligned and misaligned feeding times of light and dark feeding are associated with poor and good health outcomes, respectively. Several physiological measures were monitored continuously; blood, liver, brown adipose tissue and soleus and gastrocnemius muscle were collected following 11 days of ad libitum (AL) feeding after ending the TRF.
    RESULTS: In the dark-fed animals, the day/night differences in food intake, activity, and respiratory exchange ratio were still enhanced at the end of the experiment. Light-fed animals displayed the smallest day/night differences for these measures, as well as for body temperature. In both the light- and dark-fed animals, rhythms in plasma glucose, nonesterified fatty acids, and gene expression had not fully recovered after 11 days of AL feeding. Importantly, the effects on gene expression were both tissue- and gene-dependent.
    CONCLUSIONS: Our data indicate that rotational shift workers may have an increased risk of long-lasting disturbed rhythms in several physiological measures after a period of shift work. Clearly, such disturbances may harm their health.
  3. Front Neurosci. 2020 ;14 375
      Genes that establish the circadian clock have differential expression with respect to solar time in central and peripheral tissues. Here, we find circadian-time-induced differential expression in a large number of genes not associated with circadian rhythms in two brain regions lacking overt circadian function: the dorsal vagal complex (DVC) and the central nucleus of the amygdala (CeA). These regions primarily engage in autonomic, homeostatic, and emotional regulation. However, we find striking diurnal shifts in gene expression in these regions of male Sprague Dawley rats with no obvious patterns that could be attributed to function or region. These findings have implications for the design of gene expression studies as well as for the potential effects of xenobiotics on these regions that regulate autonomic and emotional states.
    Keywords:  central nucleus of the amygdala; diurnal rhythms; dorsal vagal complex; gene expression; qPCR