Diurnal efficacy of alpha-lipoic acid/nifedipine/glimepiride combination mitigates diabetic neuropathies in rats

OBJECTIVES

Time-dependent effects of alpha-lipoic acid/nifedipine/glimepiride combination on diabetic neuropathies were investigated in rats. 7 groups (N=9) of rats were used.

MATERIALS AND METHODS

First and second groups were apparently normal and diabetic rats respectively, and were administered 1 mL/kg distilled water. The rest of the groups were diabetic and administered 10 mg/kg glimepiride at night-time (8:00 pm). Groups 4-7 were administered additional 20 mg/kg nifedipine at morning-time (8:00 am), while groups 5-7 were also administered 100 mg/kg alpha-lipoic acid (ALA) in the morning, afternoon and night-time respectively (8:00 am, 2:00 pm and 8:00 pm). During the 28 days of oral treatment, paw pressure, tail immersion and motor coordination tests were conducted. The rats were euthanized on the 29^th day after a charcoal meal. The small intestines were excised to determine intestinal transit while the brain was collected, homogenised and used to determine levels of oxidative stress.

RESULTS

Data show that treatment with ALA at 8:00 am or 2:00 pm significantly (p ≤ 0.01) produced a delay in the onset and improved prognosis of neuropathies. Treatment with ALA at 8:00 pm prevented manifestation of neuropathies throughout the study with positive antioxidant effects.

CONCLUSION

Time-dependent ALA treatment in combination with nifedipine and glimepiride should be studied in humans with an approximately similar circadian timing. This may provide additional clinical therapeutic options for diabetic neuropathies.

[Insights and recommendations on the sleep of children and adolescents]

Sleep disorders in children are a frequent complaint, whether in maternal and child welfare, paediatrics or child psychiatry consultations. The subject should be taken into consideration in view of the significant consequences that these disorders can have on the child and his entourage. Since organic causes have been excluded, a good knowledge of sleep physiology and rhythms will enable the early childhood professional to effectively help parents to establish habits conducive to good sleep in their child.

Host-parasite life-histories of the diurnal vs. nocturnal chronotypes of Schistosoma mansoni: adaptive significance

OBJECTIVES

To optimise host-to-host transmission, digenean trematodes (parasites) synchronise their cercarial emission patterns with the aquatic activities of their vertebrate hosts. Schistosoma mansoni has two different circadian chronotypes: a diurnal shedding pattern with a mean peak occurring at 11:00 h, and a nocturnal shedding pattern with a mean peak occurring at 20:00 h. We analysed the life-history variations between these two chronotypes at the levels of the parasite and its hosts.

METHODS

For each chronotype, we quantified three life-history traits related to the parasite (prepatent period, infection rate and cercarial production) and analysed the morphometry and the morphology of the parasite eggs; we also quantified three life-history traits related to the snail intermediate host (shell diameter, fecundity and survival rate) and one life-history trait related to the experimental definitive host (survival rate). A phylogeny based on the mitochondrial cytochrome-oxidase gene was made on samples of both chronotypes.

RESULTS

Life-history analysis revealed significant variations between the two chronotypes. Life-history traits were optimal for both the parasite and the snail host for the diurnal chronotype compared to the nocturnal one. The new chronotype behaved like an allopatric population towards its snail host. Phylogenetic analysis supports the hypothesis of a lateral transfer of S. mansoni from humans to Rattus rattus. These results were interpreted in terms of an ongoing sympatric speciation.

CONCLUSION

The nocturnal chronotype of S. mansoni showed non-adapted life-history traits in its relation with the snail intermediate host Biomphalaria pfeifferi. The emergence of this new phenotype is probably linked to divergent natural selection.

[Thoughts about Light and Sleep]

Thoughts about Light and Sleep Abstract. Many aspects of health and disease are mainly determined by the constant change between light and darkness during a solar day. The resulting physiological rhythms correspond to the circadian rhythm, which was one of the most central drivers in the evolution of humans. However, over the last 20-30 years, these natural rhythms of the change of light and darkness are being increasingly ignored by modern societies. It is well known that these rhythms are modulators of many physiological pathways and any desynchronization or misalignment will activate different pathophysiological pathways, which contribute to the risk of chronic diseases. Light pollution by widespread illumination of our environment and the night sky and uncontrolled man-made use of any light source plays a key role in the pathogenesis of sleep disturbances. Blue light exposure in the evening from any artificial light source (especially from electronic device screens) is of special relevance in this context. In this article a few key facts concerning light, sleep and diseases are presented. We should by all means account for the effects of light and darkness and stop any further light pollution.

[Shift Work and Sleep]

Shift Work and Sleep Abstract. Shift work and night work are necessary in our society today. In Europe, on average about 20 % of the working population work shifts; in Switzerland it is slightly lower at 14.7 %. The proportion of the working population who regularly work night shifts is much lower: 7 % of the working population in Europe and 5 % in Switzerland. The changed daily routine in night work and shift work leads to disturbances in our biological rhythms, which adapt only slowly to the new conditions. This often leads to a lack of sleep, poor sleep quality, reduced recovery and increased strain on the body. Moreover, the unusual working rhythms are not compatible with normal family and social life. It is important that as little shift and night work as possible is performed. Those affected and their environment should be aware of the disadvantages of shift and night work in particular and know how best to adapt to the specific work situation. There is much to suggest that lack of sleep and poor sleep quality are responsible for a large proportion of the negative effects of shift work. It is therefore important to ask specific questions in this area and offer concrete support to shift workers in this regard. This overview of shift work and sleep is based on literature and our many years of practical experience with shift work counselling and training in Switzerland.

Time-restricted feeding of a high-fat diet in male C57BL/6 mice reduces adiposity but does not protect against increased systemic inflammation

Time-restricted feeding (TRF) limits the duration of food availability without altering diet composition and can combat obesity in humans and mice. For this study we evaluated the effect of timing of food access during a TRF protocol on weight gain, adiposity, and inflammation. Young male C57BL/6 mice were placed on a high-fat (HF) diet (45% fat) for 8 weeks. Food access was unrestricted (HF) or restricted to 6 h per day, either for the first half (HF-early) or the second half (HF-late) of the active phase to resemble a window of time for food consumption early or late in the day in a human population. Weight, obesity-associated parameters, and inflammation were measured. TRF reduced weight gain over the 8-week period in mice consuming the same high-fat diet. Consistent with decreased weight gain in the TRF groups, body fat percentage, liver triglycerides, and plasma leptin and cholesterol levels were reduced. Adipose tissue inflammation, measured by CD11b+F4/80+ macrophage infiltration, was reduced in both TRF groups, but systemic tumor necrosis factor-α was increased in all groups consuming the high-fat diet. The HF-late group gained more weight than the HF-early group and had increased insulin resistance, while the HF-early group was protected. Therefore, a TRF protocol is beneficial for weight management when a high-fat diet is consumed, with food consumption earlier in the day showing greater health benefits. However, increased inflammatory markers in the TRF groups suggest that diet components can still increase inflammation even in the absence of overt obesity.

Can caffeine supplementation reverse the effect of time of day on repeated-sprint exercise performance?

The aim of this study was to evaluate if caffeine can reduce the negative influence of diurnal variations on repeated-sprint performance, in addition to investigating if caffeine in the afternoon would potentiate performance compared with the morning. Thirteen physically active men took part in this randomized, double-blind, placebo-controlled and crossover study. All participants underwent a repeated-sprint ability test (10 × 6 s cycle sprints, with 30 s of rest) at 60 min after ingestion of either 5 mg·kg^-1 or placebo under 4 different conditions: morning with caffeine ingestion, morning with placebo ingestion, afternoon with caffeine ingestion, and afternoon with placebo ingestion. Total work, peak power (PP) and anaerobic power reserve (APR) were assessed. Oxygen uptake, heart rate, lactate concentration, and rating of perceived exertion were also measured during the repeated-sprint test. Total work (+8%, d = 0.2, small), PP (+6%, d = 0.2), and APR (+9%, d = 0.2) were significantly higher in the afternoon when compared with morning. However, physiological responses were not different between caffeine and placebo conditions. Repeated-sprint (10 × 6 s cycle sprint) performance was influenced by time of day, with lower performance in the morning compared with the afternoon. However, caffeine supplementation did not prevent the reduction in performance in the morning or improve performance in the afternoon.

Daytime increase in caloric intake without change in total 24-h caloric intake can increase adiposity but not total bodyweight in rats with inverted feeding pattern

The goal of this study was to evaluate the effect of the food availability period on body weight, self-selection of macronutrients, adiposity, lipoprotein, and serum glucose profiles without changing energy intake. Young male rats were divided into 2 groups according to the availability of food during the light and dark phases of the cycle, forming 2 groups: control group (CG) and group with inverted feeding pattern (IFPG). Before inversion of food availability on the 80th day, circadian food intake was measured every 4 h over 24 h during 3 days. The glycemic curve, an oral test for glucose tolerance, and self-selection of macronutrients were evaluated. Blood samples were collected for analysis of fasting glucose, triglycerides, and total cholesterol fractions. The IFPG showed an increase in fasting glucose in the dark phase of the cycle, changes in the glycemic curve, and oral glucose tolerance test. It also showed increased abdominal and liver fat and distinct choice of macronutrients compared with the CG. A change in the availability of food according to the phase of the circadian cycle produces changes in glucose and feeding circadian rhythm culminating in increased abdominal and hepatic fat. These effects can increase the risk of metabolic disorders and installation of chronic diseases.

[Circadian rhythms and chronic diseases]

Everything in nature and life is occurring in a rhythmic manner. The major “Zeitgeber” is the change of light and dark during a 24 h day. This circadian rhythm is besides others reflected in circadian rhythms of behaviors or different biochemical parameters. A disruption of the circadian rhythm has a high pathophysiological potential. In this article a few basic issues about the role of circadian rhythms and the pathophysiological importance of desynchronisation are reviewed.