Effect Of Long-term Fasting Research Articles

Effect of long-term fasting and a subsequent meal on mRNA abundances of hypothalamic appetite regulators, central and peripheral leptin expression and plasma leptin levels in rainbow trout

Knowledge about neuroendocrine mechanisms regulating appetite in fish, including the role of leptin, is inconclusive. We investigated leptin mRNA abundance in various tissues, plasma leptin levels and the hypothalamic gene expression of putative orexigenic (neuropeptide Y and agouti-regulated peptide) and anorexigenic (melanocortin receptor, proopiomelanocortins (POMCs), cocaine- and amphetamine-regulated transcript and corticotropin-releasing factor) neuropeptides in relation to feeding status in rainbow trout (Oncorhynchus mykiss). Blood and tissues were first (Day 1) sampled from trout that had been fed or fasted for 4 months and the day after (Day 2) from fasted fish after they had been given a large meal, and their continuously fed counterparts. The fasted fish ate vigorously when they were presented a meal. There were no differences between fed, fasted and re-fed fish in hypothalamic neuropeptide transcript levels, except for pomca1 and pomcb, which were higher in fasted fish than in fed fish at Day 1, and which, for pomcb, decreased to the level in fed fish after the meal at Day 2. Plasma leptin levels did not differ between fasted, re-fed and fed fish. A higher leptina1 transcript level was seen in the belly flap of fasted fish than in fed fish, even after re-feeding on Day 2. The data do not reveal causative roles of the investigated brain neuropeptides, or leptin, in appetite regulation. It is suggested that the elevated pomc transcript levels provide a satiety signal that reduces energy expenditure during prolonged fasting. The increase in belly flap leptin transcript with fasting, which did not decrease upon re-feeding, indicates a tissue-specific role of leptin in long-term regulation of energy homeostasis.

Effects of long-term fasting on female hormone levels: Ramadan model

Ramadan fasting is a special model of hunger and particularly affects metabolic processes, including carbohydrate and lipid levels. Endocrine changes induced by Ramadan fasting are not well known.The aim of this article was to evaluate the changes in hormone levels in women before and after the special Muslim fasting period of Ramadan.This study was performed in 30 healthy women in Obstetrics and Gynecology department during the Ramadan month of2011. Patients during and after the first menstrual period had menstrual cycles fasting blood samples taken on the same days. Luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol (E2), testosterone, and prolactin (PRL) levels were determined.Before and during fasting LH, FSH, E2, testosterone and PRL levels were not statistically different.Despite the limited available studies on these subjects in women, effect of Ramadan fasting on hormone levels were found to be within the normal limits.

Oxidative Stress and Antioxidant Defenses after Long-term Fasting in Blood of Chinese Sturgeon (Acipenser sinensis)

The effects of long-term fasting on the oxidative stress and antioxidant defenses in juvenile Chinese sturgeon (Acipenser sinensis) were studied. The oxidative stress biomarkers included lysozyme (LSZ), the ability of inhibiting hydroxyl radicals (AIHR), and total antioxidant capacity (T-AOC). The juvenile Chinese sturgeon were fasted for 24 hours at first. Blood samples were taken from fish a total of 8 times, upon sampling every 6 days during the remaining 48-day starvation period. The LSZ activity of juveniles generally increased as the starvation time increased. Furthermore, a significant difference in the LSZ activity of juveniles starved for 43 days was found compared with four groups starved for 1–19 days. In addition, the AIHR of juveniles first increased and subsequently decreased over the course of starvation. Specifically, the AIHR of juveniles was significantly higher in fish after 19 days of starvation than in fish sampled after 37 days of starvation, although there were no other significant differences among the levels for the other groups. The variation of the T-AOC levels of juveniles was higher during the earlier stage of starvation, and was decreased after 19 days of starvation. However, there were no significant differences among the T-AOC groups, except the T-AOC of juveniles starved for 13 days was significantly higher than that of fish starved for 37 days. It's concluded that long-term fasting influenced the antioxidant capability of juvenile Chinese sturgeon.

Circannual leptin and ghrelin levels of the blue fox (Alopex lagopus) in reference to seasonal rhythms of body mass, adiposity, and food intake

The aim of the study was to investigate the circannual rhythms of leptin and ghrelin in the blue fox, a variant of the endangered arctic fox, in relation to its seasonal cycles of body mass, adiposity and food intake. The effects of long-term fasting and exogenous melatonin treatment on these weight-regulatory hormones were also investigated. The leptin concentrations of the blue fox increased during the autumnal accumulation of fat and decreased during the wintertime and vernal weight loss periods. The leptin levels peaked 2-6 weeks before the maximum values were observed for the body mass indices, voluntary food intake, and body masses. The ghrelin concentrations fluctuated widely during the autumn but decreased in the winter in association with suppression of food intake. Exogenous melatonin advanced the seasonal changes in the food intake of the blue fox but did not affect the seasonal rhythms of leptin and ghrelin concentrations. The leptin concentrations did not respond to the 3-week fasting periods in a consistent way, but the ghrelin levels increased due to food deprivation. In addition to the amount of fat in the body the leptin secretion of the blue fox may be regulated also by other factors. The blue fox may also express seasonal changes in its leptin sensitivity. Our results reinforce the hypothesis that leptin does not function as an acute indicator of body adiposity in seasonal carnivores but rather as a long-term signal of nutritional status.

Effects of long-term fasting on insulin responses to fatty acids in man

Objective: To investigate whether the prolonged physiological elevation of non-esterified fatty acids (NEFA) seen in man during fasting associates with an altered acute insulin response to NEFA. Subjects and methods: Fourteen non-diabetic subjects, age 18-25 years, BMI 23.2 - 0.8 kg/m 2 underwent hyperglycemic clamps (blood glucose 11 mM) for 120 min, during which either saline or Intralipid was administered in the last 60 min. Subjects were tested after an overnight as well as after a 58 h fast. Results: After the overnight fast, insulin levels increased during Intralipid infusion, at min 120 reaching an increment of 33.0 - 8.5 muU/ml vs. 9.5 - 4.4 muU/ml during saline; p < 0.05 for difference. Conversely, after the 58 h fast, Intralipid failed to promote a successive increase of insulin levels (increment during Intralipid at min 120: 0.5 - 5.8 muU/ml vs.- 4.3 - 2.5 muU/ml during saline, NS). Insulin sensitivity as assessed by the amount of infused glucose and its ratio to insulin was enhanced by Intralipid after an overnight fast, but was decreased after a 58 h fast. Conclusion: Long-term elevated NEFA during fasting associates with diminished beta cell responsiveness to an acute elevation of fatty acids in conjunction with negative effects on insulin sensitivity.

Metabolic responses of Buteo buteo to long-term fasting and refeeding

1. 1. The effects of long-term fasting (13 days) and refeeding (15 days) on body mass and eight blood parameters were determined in the buzzard ( Buteo buteo). 2. 2. Body mass decreased linearly during the first 10 days of fasting. By day 13, the buzzards had lost 26% of their initial mass. 3. 3. Urea and uric acid were significantly increased by the starvation. Blood glucose and cholesterol increased during fasting. The other blood parameters were not affected by food deprivation. 4. 4. Increase in plasma globulins at the beginning of refeecling may have produced hemodilution. 5. 5. The results suggest that tissue catabolism of proteins was strongly increased in food-deprived buzzards.

The effect of long-term fasting on ketone body metabolism in the dog

1. 1. Ketone-body metabolism was studied in overnight-fasted and in 10-days fasted dogs by a ketone-body tolerance test and by infusing [ 14C]ketone bodies. 2. 2. Clearance of ketone bodies from the blood was significantly decreased after 10 days of fasting. The utilization of ketone bodies was, however, significantly higher in the fasted animals due to the increase in blood ketone-body concentrations. 3. 3. It is concluded that the low level of ketone bodies, which is characteristic for fasting dogs, results from an efficient peripheral utilization. 4. 4. The contribution of ketone bodies to the daily energy requirement of the dog has been tentatively estimated to increase from 7% in the overnight-fasted state to 13% after 10 days of starvation.

The Effect of Long-Term Fasting on the Branched Chain Acylcarnitines and Branched Chain Carnitine Acyltransferases

The effect of fasting for 8 days on the levels of carnitine acyltransferases in heart, liver, liver mitochondria, skeletal muscle, skeletal muscle mitochondria, kidney, and testes in young adult male rats was determined. The specific activities of acetyl-, octanyl-, isobutyryl-, and isovaleryl-carnitine acyltransferase in mitochondria isolated from the livers of fasted animals were significantly higher than the levels of the transferases isolated from livers of fed animals. Similar results were obtained with the 500 x g supernatant fluids from liver. In contrast, the specific activities of carnitine acyltransferases of 500 x g supernatant fractions isolated from heart, skeletal muscle, kidney, and testes were the same for fed as fasted animals. The total carnitine content of liver, muscle, heart, and kidney was less in animals fasted for 8 days than in fed animals, but the amount/g of organ was higher in the animals fasted for 8 days. The amount of specific short-chain acylcarnitines in liver, muscle, and heart was determined for both fed and fasted animals. The amount of isobutyrylcarnitine and isovalerylcarnitine increased significantly in muscle from fasted animals. These data are consistent with the previous suggestion that carnitine may have a role in the metabolism of the branched-chain amino acids.