| Undoubtly exercise has an important effect in the amendment energy regulation and the treatment human obesity, but the fat rebound after exercise cessation has been a puzzle in the field of sports medicine. Evidences of the early origins of later obesity from epidemiological data and animal models studies demonstrate that peripartum milieu can have permanent effects on the cellular structure, physiology and metabolism of offspring. Becoming overweight or obesity induced by the variations of nutrition and hormones during the critical developmental periods of fetal and/or neonatal life has shown to continue throughout childhood, juvenile life into adulthood. Since the fetal and/or neonatal life is the critical period in the prevention of obesity, we should pay more attention to the origins of obesity. Therefore the purpose of this study is to determine whether exercise during an early period (pregnant period and juvenile period) could prevent and treat the simple obesity after birth triggered by the overnutrition and whether the effects of prevention and treatment for obesity during early exercise could be prolonged. This is one of the fascinating puzzles in the field of exercise and obesity treatment.The animal model was little size Sprague-Dawley (SD) rats during the lactation in this research .The aim of the present research was to investigate the effects of early swimming exercise on the body weight programming in the offsprings of the overfeeding rats during the lactation and the fundamental underlying mechanisms by measuring the NPY,POMC and LRb in hypothalamic arcuate nucleus, serum insulin and leptin, mature adipocity apoptosis index and so on. The experiment is consisted of three parts.Part I The effects of maternal swimming exercise during pregnancy on the development and metabolism in the overfeeding rats during the lactation.Objective: To investigate whether the maternal swimming exercise during pregnancy could influence the postnatal development and metabolism of their overfeeding offspring during lactation. Methods: Eighty Virgin female SD rats (270-280g) were mated with male rats on a 1:1 ratio. After being confirmed pregnancy, pregnant rats began swimming for 10min once a day from the third day of pregnancy to delivery. On the 2nd day after birth, according to the body weight the female pups were distributed randomly and assigned to little sizes of 4 (small litters) and 10 (normal litters). Finally the offspring pups were divided into three groups during lactation: the pregnancy sedentary normal litters control group (CNC, n=16 litters) , the pregnancy sedentary small litters control group (CSC, n=15 litters) and the pregnancy swimming small litters group (ESC, n=22 litters) . Randomly selected ten dams from three groups respectively during the lactation, and then we observed the indexes of physiological development and neurobehavioral development. On the 21st days after weaning, we selected 8 rats randomly from the three groups respectively in order to measure the level of metabolism. On the 22nd days all maternal rats and the three groups' offspring rats were killed, the fasting serum glucose and lipids were assayed by enzymatic methods using commercial kits, the fasting serum insulin and leptin were assayed by radioimmunoassay, then the milk insulin and leptin were assayed by radioimmunoassay, the internal fat pads and tissues were weighted. Results: Pregnancy swimming did not significantly (P>0.05) affect the postpartum weight, serum insulin and leptin, milk insulin and leptin, FIN, FBS, IGR, serum TC and TG in the maternal rats; In comparison with the pregnancy sedentary small litters group, the opposite geotaxes reflex (P<0.05) on the 14th days after birth,memory ability (P<0.05) and the spontaneous motor activity (P<0.05) of their overfeeding pups were significantly increased in the maternal pregnancy swimming group; The body weight, milk intake, Lee index, internal fat pads weight, the ratio of the internal organ to the body weight in their pups on the day of weaning were not significantly altered by maternal pregnancy swimming (P>0.05). Suggestion: To increase the level of maternal physical activity during pregnancy, the nervous reflex,memory ability and the spontaneous motor activity of the rats' offspring could be enhanced by the maternal pregnancy swimming, however, there was little effect on the body weight phenotype and the metabolic level of their overfeeding pups during weanling.Part II The effects of maternal swimming during pregnancy on the expressions of NPY,POMC and LRb in the overfeeding rat pups during weanlingObjective: To investigate whether the maternal swimming exercise during pregnancy could influence the regulation center of appetite and energy in the arcuate nucleus of hypothalamus of their overfed weanling rats. Methods: The animal model was the same as that in part one, after weaning they were randomly distributed and assigned to three groups: the pregnancy sedentary normal little control group (CNC1, n=8) , the pregnancy sedentary postweaning OF control group (CSC1, n=8 ) and the pregnancy swimming postweaning OF group (ESC1, n=8 ) .After weaning the rat pups' brains were removed, NPYmRNA, POMCmRNA and LRbmRNA in the arcuate nucleus of hypothalamus were analyzed using with in situ hybridization technique, NPY and POMC in the arcuate nucleus of hypothalamus were analyzed with immunohistochemical technique .The fasting serum insulin and leptin were assayed by radioimmunoassay, and the fasting serum glucose and lipids were assayed by enzymatic methods using commercial kits. Results: The body weight, Lee index, interval fat pads weight, serum leptin, FIN, FBS, IGR and serum TC in their pups on the day of weaning, relative to Group CSC1, were not significantly affected in Group ESC1. POMC and POMCmRNA exhibition were significantly higher in Group CSC1 than that in Group CNC1 (P<0.01), while Group ESC1 were enhanced significantly by the materal swimming during pregnancy (P<0.01 and P<0.01). However the positive expressions of NPYmRNA and NPY, compared with the pregnancy sedentary normal little group during the weaning period, were not significantly affected by maternal swimming in the arcuate nucleus of hypothalamus of the overfeeding rats (P>0.05). We couldn't find any significant improvement of the lower positive expression of LRbmRNA in the arcuate nucleus of hypothalamus of the Group ESC1 in compared with the Group CSC1 during the weaning period (P>0.05). Suggestion: This study demonstrates that maternal swimming during pregnancy has little significant preventive effect on the weight programming in the overfeeding rats. However the present results have clearly shown that maternal swimming by rats during pregnancy significantly enhance the positive expressions POMCmRNA and POMC within the arcuate nucleus of hypothalamus of the rats' overfed offspring, which suggests that maternal swimming during pregnancy could further enhance the protective response to the overfeeding during lactation.Part III The effects of swimming during pregnancy and postweaning on the body weight programming in the juvenile overfeeding rats.Objective: To investigate whether early swimming exercise has long-term effects on the appetite peptides of hypothalamus, interval fat accumulation and the adipocyte apoptosis in the juvenile overfeeding rats of their mothers swimming during pregnancy. The animal model was the same as that in part one. After weaning they were randomly distributed according to body weight and assigned to five groups according to the swimming sessions: the pregnancy sedentary with postweaning 7wks sedentary control group (CNC2, n=8) , the pregnancy sedentary with postweaning 7wks sedentary OF control group (CSC2, n=8) ,the pregnancy swimming with postweaning 7wks sedentary OF group (ESC2, n=8) , the pregnancy swimming with postweaning 7wks swimming OF group (ESE1, n=8) and the pregnancy swimming with postweaning 3wks swiming+4wks sedentary OF group (ESE2, n=8) . A 7-week progressive exercise programme consisted of a 7-day adaptation period and 6-week exercise period. The postweaning overfeeding rats began swimming at 20mins/day, 6days/wk and increased to a 45mins/day by the six days, then the juvenile overfeeding rats began swimming at 45mins/day, 6days/wk and increased to a 80mins/day by six weeks. At the 10 weeks of age the animals were starved overnight and were decapitated in the next day. NPY and POMC in the arcuate nucleus of hypothalamus were analyzed with immunohistochemistrical technique. The fasting serum insulin and leptin were assayed by radioimmunoassay, the fasting serum glucose and lipids were assayed by enzymatic methods using commercial kits. The apoptotic index and the numuber of adipocyte in retroperitoneal (RP) fat pad apoptotic index were detected by flow cytometric analysis. The size of RP adipocyte was observed by the HE-staining and image analysis was used to measure the mean area. Results: (1) Body composition and food consumption: No significant (P>0.05) differences were found between the Group ESC2 and Group CSC2 (P>0.05) with regard to the body weight, internal fat mass and the food consumption per day at the 10 weeks of age. The body weight, internal fat mass and the food consumption per day were significantly lower in both Group ESE1 and Group ESE2 than that was in Group CSC2(P<0.01) and the differences were also not sufficiently large to be significant (P>0.05) between the two groups. (2)Serum parameters: No significant (P>0.05) differences were found between Group ESC2 and Group CSC2 with regard to the Serum parameters at the 10 weeks of age. The serum levels of FIN,IGR,leptin and TG were significantly lower in both Group ESE1 and Group ESE2 than that in Group CSC2(P<0.01) and there were no significant differences on the levels of the FINS,leptin and TG in the two groups(P>0.05). (3)Anorexia peptides: The positive expressions of NPY and POMC in the arcuate nucleus of hypothalamus were obviously higher in Group ESE1 and Group ESE2 than that in Group CSC2 (P<0.01), and there were no significant differences between the ESE1 group and ESE2 group (P>0.05). (4) Adipocyte parameters: RP fat pad apoptotic index was obviously higher in Group ESE1 and Group ESE2 than that in Group CSC2 (P<0.01). While the number of RP adipocyte was obviously lower in Group ESE1 and Group ESE2 than that in Group CSC2 (P<0.01). And there were no significant differences on the mean area of RP adipocyte (P>0.05). Both of Group ESE1 and Group ESE2 did not show significant (P>0.05) differences in the apoptotic index, the number of RP adipocyte, and the mean area of RP adipocyte. Suggestion: These results indicate that maternal swimming itself during pregnancy in order to increasing the level of physical activity has no long-term prevention effects on the interval fat accumulation and the body weight programming in the overfeeding rats; The early swimming during the pregnancy and juvenile could improve the interval fat accumulation and the body weight programming in the 10-weeks age overfeeding rats, and these effects can remain for 4 weeks after the early swimming termination at the six weeks age of the overfeeding rats.Conclusions: (1) There was a little effect on the body weight phenotype, the accumulation of internal fat mass and the metabolic level of their overfeeding pups during weaning, however, it could increase the nervous reflex on the 14th days after birth, memory ability and the spontaneous motor activity of the 21-days age OF rats. Furthermore it could enhance expressions POMCmRNA and POMC within the arcuate nucleus of hypothalamus of the rats' overfed offspring, which is the protective response to the overfeeding during lactation. (2)Maternal pregnancy swimming exercise have a little preventive effect on the body weight programming of the overfeeding rat during weanling. The underlie mechanism is that the serum leptin and FIN levels in the overfeeding offspring of pregnancy swimming mother rats didn't increased with the expression levels of POMCmRNA and POMC in the hypothalamic arcuate nucleus. (3)The early swimming during the pregnancy and juvenile has a prolonged ameliorative effect on the body weight programming of the overfeeding rat. The underly mechanism is the serum leptin level in the OF rats with the pregnancy swimming and postweaning 3wks swimming increased with the with the expression levels of POMCmRNA and POMC in the hypothalamic arcuate nucleu. Moreover their apoptotic index for the visceral fat cells kept higher for four weeks and the number of visceral fat cells was also no significant increase. (4)The synergistic regulation among the central peptides, circulation hormones and adipocyte is key for the early swimming lasting improvement the body weight programming of the Overfeeding Rats.This research provides a pioneer way in the effects and mechanism of early swimming exercise on the body weight programming in the overfeeding Rats. Then we brought forward that by increasing the physical activities of the pregnant mother have the benefit synergistic effect on the overweight or obese children induced by overnutrition during lactation in the following exercise treatment. We provided experimental base for the further studies of the association's pregnancy exercise and the mothers' offspring in these aspects of study and memory, appetite and energy regulation, appetite, adipose development and adipocyte physiological apoptosis. Moreover this work presents a new approach of exercise therapy for children overweight and obesity.
|
PDF Full Text Request