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Effects of acute starvation and of type 2 diabetes mellitus upon insulin resistance and substrate utilization in obese subjects
Duška, František ; Anděl, Michal (advisor) ; Haluzík, Martin (referee) ; Mourek, Jindřich (referee) ; Stárka, Luboslav (referee)
Very-low calorie diet or even total short-term fasting is widely used in clinical practice in order to improve metabolic compensation of patients with type 2 diabetes mellitus. Although benefits of weight reduction are well proven in T2DM, much less is known about effects of acute starvation, during which the interruption of the afflux of energy substrates is not followed by a major change of body composition. We hypothesize the improvement of insulin effects on glucose metabolism in T2DM as these patients may lack the key metabolic responses which impair insulin sensitivity in lean, non-diabetic subjects. Moreover, we assume according to "thrifty genotype hypothesis" that protein wasting during starvation will be positively related to insulin effects on glucose disposal and negatively related to insulin antilipolytic and antiketogenic effects. In the light of this we designed an observational, prospective, in-hospital study, comparing the effects of 60 hours fast on various aspects of insulin resistance, endocrine regulation and metabolism in 10 patients with T2DM and 10 obese controls without diabetes (OB).
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Entrainment of the circadian clock within the rat suprachiasmatic nukleus during fetal and early postnatal development
El-Hennamy Essam, Rehab ; Sumová, Alena (advisor) ; Novotná, Růžena (referee) ; Mourek, Jindřich (referee)
All mammals exhibit daily rhythms which persist in non-periodic environment with a period close to 24h. These rhythms are entrained to the 24h day mostly by the light-dark cycle. These circadian rhythms are controlled by a clock (pacemaker) located in the suprachiasmatic nuclei (SCN) of the hypothalamus. In the rat, the circadian clock within the SCN develops gradually from prenatal to postnatal period and is supposed to be synchronized mainly by maternal signals. However, the rat SCN is sensitive to light immediately after birth. The aim of the present work was to investigate the mechanism of entrainment of the circadian clock within the rat SCN during fetal and early postnatal development. The specific questions were whether and when the immature fetal and neonatal molecular SCN clocks can be reset by maternal cues, and whether and when the external light-dark cycle (LD) can affect the developing circadian rhythms. The role of light-dark cycle in the development of the photoperiodic entrainment during early postnatal period was also examined. Experiment no. (1): Pregnant rats were maintained under a light - dark regime with 12 h of light and 12 h of darkness (LD12:12). At gestational day 20 (E20), the fetuses were sampled throughout the day under either LD12:12 or constant darkness (DD). The...
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Effects of acute starvation and of type 2 diabetes mellitus upon insulin resistance and substrate utilization in obese subjects
Duška, František ; Anděl, Michal (advisor) ; Haluzík, Martin (referee) ; Mourek, Jindřich (referee) ; Stárka, Luboslav (referee)
Very-low calorie diet or even total short-term fasting is widely used in clinical practice in order to improve metabolic compensation of patients with type 2 diabetes mellitus. Although benefits of weight reduction are well proven in T2DM, much less is known about effects of acute starvation, during which the interruption of the afflux of energy substrates is not followed by a major change of body composition. We hypothesize the improvement of insulin effects on glucose metabolism in T2DM as these patients may lack the key metabolic responses which impair insulin sensitivity in lean, non-diabetic subjects. Moreover, we assume according to "thrifty genotype hypothesis" that protein wasting during starvation will be positively related to insulin effects on glucose disposal and negatively related to insulin antilipolytic and antiketogenic effects. In the light of this we designed an observational, prospective, in-hospital study, comparing the effects of 60 hours fast on various aspects of insulin resistance, endocrine regulation and metabolism in 10 patients with T2DM and 10 obese controls without diabetes (OB).
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