Preventive Effect of Serotonergic Drugs on LPS-Induced Acute Anorexia in Rats

The aim of the present study was to determine whether serotonergic drugs could reverse lipopolysaccharide (LPS) -induced anorexia in rats. LPS (500microgram/kg body weight) and all serotonergic drugs, except for 8-OH-DPAT (subcutaneous), were injected intraperitoneally into Sprague-Dawley rats. Without the LPS injection, 8-OH-DPAT (1A agonist), metergoline (1/2 antagonist), and mianserin (2A/2C antagonist) exerted no effects on food intake at any of the doses tested, but ketanserin (2A antagonist) caused an increase of food intake at 4 mg/kg. RS-102221 (2C antagonist) reduced food intake at 2 and 4 mg/kg. LPS reduced food intake 1 hour after injection, and food intake remained low until the end of measurement period (24 hours) (p< 0.05). Pretreatment of rats with 8-OH-DPAT partially recovered of cumulative food intake at all measured times (2, 4, 6, 8, and 24 hours after LPS injection). Pretreatment with metergoline resulted in a partial recovery of cumulative food intake at 2, 4, 6, and 8 hours, but not at 24 hours. Ketanserin caused partial recovery at 2 and 4 hours only. Mianserin and RS-102221 had no effects on LPS-reduced food intake. A variety of serotonergic drugs ameliorated anorexic symptoms, which suggesting that the serotonin system plays a role in LPS-induced anorexia.

Fuctional Relationship between Rate of Fatty Acid Oxidation and Carnitine Palmitoyl Transferase I Activity in Various Rat Tissues

Lipids play many structural and metabolic roles, and dietary fat has great impact on metabolism and health. Fatty acid oxidation rate is dependent on tissue types. However there has been no report on the relationship between the rate of fatty acid oxidation and carnitine transport system in outer mitochondrial membrane of many tissues. In this study, the rate of fatty acid oxidation and carnitine palmitoyltransferase (CPT) I activity in the carnitine transport system were measured to understand the metabolic characteristics of fatty acid in various tissues. Palmitic acid oxidation rate and CPT I activity in various tissues were measured. Tissues were obtained from the white and red skeletal muscles, heart, liver, kidney and brain of rats. The highest lipid oxidation rate was demonstrated in the cardiac muscle, and the lowest oxidation rate was in brain. Red gastrocnemius muscle followed to the cardiac muscle. Lipid oxidation rates of kidney, white gastrocnemius muscle and liver were similar, ranging from 101 to 126 DPM/mg/hr. CPT I activity in the cardiac muscle was the highest, red gastrocnemius muscle followed by liver. Brain tissue showed the lowest CPT I activity as well as lipid oxidation rate, although the values were not significantly different from those of kidney and white gastrocnemius muscle. Therefore, lipid oxidation rate was highly (p< 0.001) related to CPT I activity. Lipid oxidation rate is variable, depending on tissue types, and is highly (p< 0.001) related to CPT I activity. CPT I activity may be a good marker to indicate lipid oxidation capacity in various tissues.

The Effect of Long Chain N-3 Polyunsaturated Fatty Acids on Development of Collagen-induced Arthritis in Rats / 영남의대학술지

BACKGROUND: The treatment of rheumatoid arthritis still depend on conserve therapy in major. Recent studies report that n-3 polyunsaturated fatty acids(PUFA) could modulate the incidence and progress of arthritis. The purpose of this study was to investigate the effects of n-3 PUFA on the development of collagen-induced arthritis in rats. MATERIALS AND METHODS: Female Louvain rats were used for this experiment. Rats were randomly assigned into either normal(n=8) or collagen-immunized groups, and collagen immunized groups were divided into control(n=8, normal diet) and n-3 PUFA(n=8, 5% n-3 PUFA in diet) groups. One week after feeding n-3 PUFA to rats, they were immunized with type II collagen emulsified in incomplete Freund's adjuvant into tail and back. Development of arthritis was confirmed by x-ray and microscopic examination. RESULTS: Incidence of arthritis at the 5th week after immunization was 38% in control and 0% in n-3 PUFA. Rats with arthritis showed edema in hind paws and inflammation in synovial membrane of the knee joint. Plasma glucose and insulin were not changed by both of immunization and diet. Plasma triglycerides and cholesterol concentrations were decreased by n-3 PUFA. CONCLUSION: n-3 PUFA may prevent or treat collagen-induced arthritis in rats. Further studies are needed for action mechanism of it.

The Effect of Long Chain N-3 Polyunsaturated Fatty Acids on Development of Collagen-induced Arthritis in Rats / 영남의대학술지

BACKGROUND: The treatment of rheumatoid arthritis still depend on conserve therapy in major. Recent studies report that n-3 polyunsaturated fatty acids(PUFA) could modulate the incidence and progress of arthritis. The purpose of this study was to investigate the effects of n-3 PUFA on the development of collagen-induced arthritis in rats. MATERIALS AND METHODS: Female Louvain rats were used for this experiment. Rats were randomly assigned into either normal(n=8) or collagen-immunized groups, and collagen immunized groups were divided into control(n=8, normal diet) and n-3 PUFA(n=8, 5% n-3 PUFA in diet) groups. One week after feeding n-3 PUFA to rats, they were immunized with type II collagen emulsified in incomplete Freund's adjuvant into tail and back. Development of arthritis was confirmed by x-ray and microscopic examination. RESULTS: Incidence of arthritis at the 5th week after immunization was 38% in control and 0% in n-3 PUFA. Rats with arthritis showed edema in hind paws and inflammation in synovial membrane of the knee joint. Plasma glucose and insulin were not changed by both of immunization and diet. Plasma triglycerides and cholesterol concentrations were decreased by n-3 PUFA. CONCLUSION: n-3 PUFA may prevent or treat collagen-induced arthritis in rats. Further studies are needed for action mechanism of it.

Effect of Age on Glucose Metabolism of Skeletal Muscle in Rats / 영남의대학술지

BACKGROUND: It is doubtful that aging causes deteriorated glucose metabolism and insulin resistance of skeletal muscle. Some researchers had different results about it. So we have studied the mechanism responsible for the abnormal glucose tolerance associated with aging in rapidly growing and matured rats. MATERIALS AND METHODS: Animals were used S.D. rats. Growing rats were 7 weeks old (BW: 160-190 gm) and matured rats were 28 weeks old (BW: 420-525 gm). RESULTS: Fasting blood glucose and plasma insulin levels were significantly elevated in matured rat compared with growing rats. And during oral glucose tolerance test the glucose level was also significantly elevated in matured rats. These results confirmed an insulin resistant state of aging. Insulin levels at 30 minutes of oral glucose tolerance test was significantly elevated in growing rat. But at 120 minutes it was maintained at higher level in matured rats than in growing rats. It suggested the possibility of increased insulin secretion by initial stimulation of beta-cells in growing rats, and increased secretion and decreased catabolic rate of insulin in matured rats. Glucose uptake rate of soleus muscle in matured rats was lower than that of growing rats, but the difference was not statistically significant. The dose(insulin)- responsive (glucose uptake) curve of soleus muscle was only slightly deviated to the right side. CONCLUSION: Glucose metabolism of rat skeletal muscle was worsened by aging. The data of glucose uptake experiments suggested the possibility of insulin resistance of skeletal muscle in matured rats, but the mechanism of insulin resistance of skeletal muscle need further studies.

Effect of High Fat Diet on Insulin Resistance: Dietary Fat Versus Visceral Fat Mass

The purpose of the present study was to determine whether chronic high-fat diet (HF) induces insulin resistance independently of obesity. We randomly divided 40 rats into two groups and fed them either with a HF or with a high-carbohydrate diet (HC) for 8 weeks. Whole body glucose disappearance rate (Rd) was measured using a euglycemic hyperinsulinemic clamp. Firstly, we defined whether insulin resistance by HF was associated with obesity. Plasma glucose and triglyceride concentrations were significantly increased in HF. Rd was decreased (10.6+/-0.2 vs. 9.1+/-0.2 mg/kg/min in HC and HF, respectively) and the hepatic glucose output rate (HGO) was increased in HF (2.2+/-0.3 vs. 4.5+/-0.2 mg/kg/min in HC and HF, respectively). Rd was significantly correlated with %VF (p<0.01). These results implicate that visceral obesity is associated with insulin resistance induced by HF. In addition, to define whether dietary fat induces insulin resistance regardless of visceral obesity, we compared Rd and HGO between groups 1) after matching %VF in both groups and 2) using an ANCOVA to adjust for %VF. After matching %VF, Rd in HF was significantly decreased by 14% (p<0.001) and HGO was significantly increased by 110% (p<0.001). Furthermore, statistical analyses using an ANCOVA also showed Rd for HF was significantly decreased even after adjusting %VF. In conclusion, we suggest that dietary fat per se could induce insulin resistance in rats fed with chronic HF independently of obesity.

Combined trial of fish oil and exercise training prevents impairment in insulin action on glucose transport of skeletal muscle induced by high-fat diet in rats

The purpose of the present study was to determine the preventive effects of combined interventional trial of fish oil treatment and exercise training on insulin resistance of skeletal muscle in high-fat fed rats. Male Wistar rats were randomly divided into chow diet (CD), high-fat diet (HF), high-fat diet with fish oil (FO), high-fat diet with exercise training (EX), and FO+EX groups. The rats in control group were fed chow diet containing, as percents of calories, 58.9% carbohydrate, 12.4% fat, and 28.7% protein. High-fat diet provided 32% energy as lard, 18% as corn oil, 27% as carbohydrate and 23% as casein. The fish oil diet had the same composition as the high fat diet except that 100 g menhaden oil was substituted for corn oil. Insulin sensitivity was assessed by in vitro glucose transport in the soleus muscle after diet treatment and treadmill running for 4 weeks. While the FO or EX only partially prevented insulin resistance on glucose transport and visceral obesity induced by high-fat diet, these interventions completely corrected hyperinsulinemia and hyperglycemia from the high-fat diet. The rats in the FO+EX showed normalized insulin action on glucose transport, plasma chemicals and visceral fat mass. Insulin-mediated glucose transport was negatively associated with total visceral fat mass (r=-0.734; p<0.000), plasma triglyceride (r=-0.403; p<0.05) and lepin (r=-0.583; p<0.001) concentrations with significance. Multiple stepwise regression analysis showed that only total visceral fat mass was independently associated with insulin-mediated glucose transport (r=-0.668; p<0.000). In conclusion, combined interventional trial of FO+EX recovered insulin resistance on glucose transport of skeletal muscle induced by high-fat diet. Visceral fat mass might be more important factor than plasma TG and leptin to induce insulin resistance on glucose transport of skeletal muscle in high-fat fed rats.

Change in activity of the sympathetic nervous system in diet-induced obese rats

We investigated the change in activity of the sympathetic nervous system (SNS) in high-sucrose diet (HSD)-induced obese rats compared with controls. Power spectral analyses of R-R interval variability were performed to obtain the low frequency (LF, 0.04-0.699 Hz) and high frequency (HF, 0.7-3.0 Hz) powers. The percents of fat mass to body weight (%F/BW) and fat to muscle ratios (F/M) were significantly increased in HSD-fed rats. Plasma glucose, leptin, and triglyceride concentrations in rats fed with HSD were significantly increased. LF in normalized units (LFn), which represents both sympathetic and parasympathetic activities, was significantly increased whereas HF in normalized unit (HFn), which represents parasympathetic activity, was significantly decreased in HSD-fed rats. LF/HF, which represents sympathetic activity, was significantly increased in HSD-fed rats and was correlated with leptin (r=0.549, p<0.023), %F/BW (r=0.513, p<0.035), F/M (r=0.536, p<0.038), and triglyceride (r=0.497, p<0.042). When adjusted for leptin concentrations, however, LF/HF of HSD-fed rats was significantly decreased. In conclusion, HSD-induced obese rats showed increased LF/HF, which was significantly decreased by adjustment for leptin concentrations. We suggest that stimulating effect of leptin on SNS is reduced, which might play a role in induction of obesity by HSD.

Effect of Exercise on Antioxidant Enzyme Activities of Skeletal Muscle and Liver in STZ-diabetic Rats / 영남의대학술지

BACKGROUND: The purpose of the present study was to investigate the effect of exercise on the activities of antioxidant enzymes, superoxide dismutase(SOD), glutathione peroxidase(GPX) and catalase(CAT) of skeletal muscle(gastrocnemius) and liver in streptozotocin(STZ) induced diabetic rats. The malondialdehyde(MDA) concentration was also measured as an index of lipid peroxidation of the tissues by exercise-induced oxidative stresses in the diabetic rats. MATERIAL AND METHODS: Male Sprague-Dawley rats were randomly divided into control and STZ-induced diabetic rats. The STZ in citrate buffer solution was injected twice at 5 days intervals intraperitoneally(50, 70 mg/kg respectively). On the 28th day after the first STZ injection, the diabetic animals were randomly divided into pre- and post-exercise groups. The exercise was introduced to the rats of post-exercise group by treadmill running till exhaution with moderate intensity (VO2max: 50-70%) of exercise. The duration of average running time was 2 hours and 19 minutes. RESULTS: The blood glucose concentration was increased(p<0.001) and plasma insulin concentration was decreased(p<0.001) in the diabetic rats. The glycogen concentration in the muscle and liver was decreased by exhaustive exercise in the diabetic rats(p<0.001). In the skeletal muscle, the activities of GPX was increased(p<0.05) and the activities of SOD and CAT were not changed in the diabetic rats compare to the control rats. The activities of GPX was not changed by exercise but the activities of SOD(p<0.01) and CAT (p<0.01) were decreased by exercise in the diabetic rats. The concentration of MDA was not changed by exercise in diabetic rats. and the values of pre-exercise and post-exercise diabetic rats were not different from the value of control rats. In the liver, the activities of SOD was decreased(p<0.01) and the activities of GPX and CAT were not changed in diabetic rats compared to the values of control rats. The activities of SOD, GPX and CAT were not changed by exercise in diabetic rats but the the slight decreasing tendency of the activity of SOD was observed. The MDA concentration was increased in the diabetic rats compared to the values of control rats(p<0.001) but there was no change of MDA concentration by exercise in diabetic rats. CONCLUSIONS: In summary, the exhaustive physical exercise has not been shown to impose oxidative stress on skeletal muscle due to oxygen free radicals regardless of decreament of SOD and CAT in the diabetic rats. In liver tissue, the tissue damage by oxidative stress was observed in diabetic rats but the additional tissue damage by the exhaustive physical exercise was not observed.

Effects of BCG, lymphotoxin and bee venom on insulitis and development of IDDM in non-obese diabetic mice

To investigate whether BCG, lymphtoxin (LT) or bee venom (BV) can prevent insulitis and development of diabetes in non-obese diabetic (NOD) mice, we measured the degree of insulitis and incidence of diabetes in 24 ICR and 96 female NOD mice. NOD mice were randomly assigned to control, BCG-, LT-, and BV-treated groups. The BCG was given once at 6 weeks of age, and LT was given in 3 weekly doses from the age of 4 to 10 weeks. The BV was injected in 2 weekly doses from the age of 4 to 10 weeks. Diabetes started in control group at 18 weeks of age, in BCG group at 24 weeks of age, and in LT- or BV-treated group at 23 weeks of age. Cumulative incidences of diabetes at 25 weeks of age in control, BCG-, LT-, and BV-treated NOD mice are 58, 17, 25, and 21%, respectively. Incidence and severity of insulitis were reduced by BCG, LT and BV treatment. In conclusion, these results suggest that BCG, LT or BV treatment in NOD mice at early age inhibit insulitis, onset and cumulative incidence of diabetes.

Surgical removal of visceral fat decreases plasma free fatty acid and increases insulin sensitivity on liver and peripheral tissue in monosodium glutamate (MSG)-obese rats

In order to evaluate the role of visceral and subcutaneous fat tissue in insulin sensitivity and lipid metabolism, we measured the fasting levels of plasma free fatty acid (FFA) and insulin, glucose disappearance rate (Rd), and hepatic glucose production rate (HGP) after surgical removal of visceral (VF) or subcutaneous (SF) fat tissue in monosodium glutamate-obese (MSG-Ob) rats. Monosodium glutamate obesity was induced in rats by neonatal injection of MSG. Surgery to remove fat was done at 15 weeks of age. The experiments were done four weeks after the surgery. MSG-Ob rats showed increased levels of FFA, insulin, and HGP and decreased Rd compared to normal rats. In the VF group, the FFA level and HGP were decreased to normal values, Rd was partially normalized, but the level of insulin did not change significantly compared to MSG-Ob. In the SF group, FFA and Rd were partially normalized, but HGP was not suppressed significantly compared to MSG-Ob. These results suggest that visceral fat affects the insulin sensitivity of liver and FFA concentration more than subcutaneous fat; however, no significant difference was shown on whole body insulin sensitivity and fasting insulin concentration.

Post - Exercise Glycogen Supercompensation in Liver and Muscle after Glucose Ingestion in Rats / 대한정형외과학회잡지

The muscle glycogen is an important energy source for muscle contraction especially in prolonged exercise. One of the important factors for improvement of physical performance in athletes is the storage of extra-amount of glycogen (supercompensation) in liver and muscles. During 120 minutes treadmill exercise (intensity of exercise was approximatly 80% VO2max), the glycogen concentration was significantly decreased to 36% in liver and 46% in muscles after 60 minutes exercise. At 90 and 120 minutes of exercise, the level of glycogen concentration of liver and muscles statistically were not different from the levels of the 60 minutes exercise. The repletions of glycogen in the liver and muscles in overnight fasted control(C) and 120 minutes treadmill exercise(E) groups during l80minutes after glucose ingestion were investigatect. ln the liver, the concentration of glycogen in C and E groups were markdly increased till 120 minutes after zlucose ingestion, hut the levels of concentration at 180 minutes were decreased comparing to the levels of 120 minutes in both groups. In the muscles, the repletion of glycogen at 60, 120 and 180 minutes of C and E groups were significantly increased comparing to 0 minute of respective groups in the soleus and plantaris muscles. In soleus(SOL), the repletion of glycogen in all of the E groups was significantly higher than that of the respective C groups. However, the repletion of glycogen in all of the E groups of plantaris was revealed higher tendency comparing to respective C groups. Mean repletion rates of glycogen in liver and muscles after glucose ingestion were highest during the first 60 minutes in all groups and the rates of E groups were 2-3 times than those of respective C groups. These results suggest that the glycogen supercompensation in the muscle be provided with decrement of glycogen concentration by exercise, increment of glucose uptake by muscuiar contraction itself and increased insuJin level, and the activation of glycogen synthetase by insulin.

Effect of Hyperglycemia and Hyperlipidemia on Cardiac Muscle Glycogen Usage during Exercise in Rats / 영남의대학술지

Rats were studied during 45 minutes treadmill exercise to determine the effects of hyperglycemia and hyperlipidemia on the utilization of cardiac muscle glycogen, and the utilization of diaphragm muscle glycogen was also studied for comparing to cardiac muscle. The hyperglycemia was produced by ingestion of 25% glucose solution(1ml/100gm, BW) and the hyperlipidemia by 10% intralipose ingestion(1ml/100gm, BW) with intraperitoneal injection of heparin(500 IU) 15 minutes before treadmill exercise. The mean blood glucose concentrations(mg/dL) in control and hyperglycemic rats were 110 and 145, respectively, and the mean plasma free fatty acid concentrations(micronEq/L) in control, control exercise(control-E) and hyperlipidemia exercise(HL-E) rats were 247, 260 and 444, respectively. In the hyperglycemic trial, the cardiac muscle glycogen concentration was not significantly decreased by the exercise but the concentration in control rats was decreased to 73.9%(p<0.05). The glycogen concentration of diaphragm was significantly decreased in both groups by the exercise, but the hyperglycemia decreased the glycogen utilization by approximately 10% compared to the control. The cardiac muscle glycogen concentration was not decreased by the exercise in control and hyperlipidemic rats but the utilization of glycogen in hyperlipidemic rats is lower than that of the control. These data illustrate the sparing effect of hyperglycemia on cardiac muscle glycogen usage during exercise, but the effect of hyperlipidemia was not conclusive. In the skeletal muscle, the usage of glycogen by exercise was spared by both hyperglycemia and hyperlipidemia.

Effects of Regular Treadmill Running on GLUT4 Protein of Skeletal Muscle in STZ-diabetic Rats / 영남의대학술지

The purpose of this study was to investigate the effects of regular treadmill running on GLUT4 protein of skeletal muscle in STZ-diabetic rats. I used 19 male Sprague-Dawley rats weighing 140 to 160 grams. Rats were randomly assigned into normal, diabetes(DM) and DE(DE) groups. The exercise was loaded with treadmill running for 5 days per week during 4 weeks. All experimental procedures were carried out following overnight fasting 48 hours after last exercise. Gain(gm) in body weight in DM rats(82+/-2.4) was lowered compared to normal rats(109+/-2.8), and decreased by exercise. Plasma glucose concentration(mg/dl) in DM rats was 143+/-3.1 which is higher than that of normal group of 103+/-6.4. The concentration of DE group was lower than that of DM rats. Plasma insulin concentration(micronU/ml) of DM and DE rats was significantly lowerd compared to normal rats. There was no difference of plasma concentrations of FFA and HDL cholesterol among noraml, DM and DE groups. Plasma triglyceride concentration(mg/dl) was significantly highered in DM group compared to those of DM group, the concentration of DE group was lower. Glycogen concentration(mg/gm wet weight) of the plantaris muscle in DM and DE groups was significantly reduced compared to normal group. Glucose transporter 4(GLUT4) protein of soleus was analyzed by Western blot. In DM group, the GLUT4 protein level was markdly decreased compared to normal group, but the level was recovered to the level of normal group by 4 weeks treadmill running. In conclusion, the insulin resistance induced by STZ administration was partially improved by 4 weeks physical training in rats.

Effect of Acutely Increased Glucose Uptake on Insurin Sensitivity in Rats / 영남의대학술지

Insulin resistance is a prominent feature of diabetic state and has heterogeneous nature. However, the pathogenetic sequence of events leading to the emergence of the defect in insulin action remains controversial. It is well-known that prolonged hyperglycemia and hyperinsulinemia are one of the causes of development of insulin resistance, but both hyperglycemia and hyperinsulinemia stimulate glucose uptake in peripheral tissue. Therefore, it is hypothesized that insulin resistance may be generated by a kind of protective mechanism preventing cellular hypertrophy. In this study, to evaluate whether the acutely increased glucose uptake inhibits further glucose transport stimulated by insulin, insulin sensitivity was measured after preloaded glucose infusion for 2 hours at various conditions in rats. And also, to evaluate the mechanism of decreased insulin sensitivity, insulin receptor binding affinity and glucose transporter 4 (GLUT4) protein of plasma membrane of gastrocnemius muscle were assayed after hyperinsulinemic euglycemic clamp studies. Experimental animals were divided into five groups according to conditions of preloaded glucose infusion: group I, basal insulin (14+/-1.9 micronU/ml) and basal glucose (75+/-0.7 mg/dl), by normal saline infusion; group II, normal insulin (33+/-3.8 micronU/ml) and hyperglycemia (207+/-6.3 mg/dl), by somatostatin and glucose infusion; group III, hyperinsulinemia (134+/-34.8 micronU/ml) and hyperglycemia (204+/-4.6 mg/dl), by glucose infusion; IV, supramaximal insulin (100+/-2.2 mg/dl), by insulin and glucose infusion; group V, supramaximal insulin(4813+/-687.9 micronU/ml) and hyperglycemia (233+/-3.1 mg/dl), by insulin and glucose infusion. Insulin sensitivity was assessed with hyperinsulinemic euglycemic clamp technique. The amounts of preloaded glucose infusion(gm/kg) were 1.88+/-0.151 in group II, 2.69+/-0.239 in group III, 3.54+/-0.198 in groupIV, and 4.32+/-0.621 in group V. Disappearance rates of glucose (Rd, mg/kg/min) at steady state of hyperinsulinemic euglycemic clamp studies were 16.9+/-3.88 in group I, 13.5+/-1.05 in group II, 11.2+/-1.17 in group III, 13.2+/-2.05 in group IV, and 10.4+/-1.01 in group V. A negative correlation was observed between amount of preloaded glucose and Rd )r=-0.701, p<0.001) when all studies were combined. Insulin receptor binding affinity and content of GLUT4 were not significantly different in all experimental groups. These results suggest that increased glucose uptake may inhibit further glucose transport and lead to decreased insulin sensitivity.

Utilization of Supercompensated Glycogen of Hindlimb Muscles during Strenous Exercise in Rats / 영남의대학술지

The aim of the present investigation has been to evaluate the depletion pattern of the supercompensated glycogen of hindlimb muscles during strenous exercise in rats. The plan of the maximizing muscle glycogen stores is based on the fact that a glycogen-depleted muscle by exercise will have an increased avidity for glycogen when exposed to a high carbohydrate diet. The glycogen concentration of soleus, red gastrocnemius and plantaris muscle, and liver was measured at 0, 30 and 60 minutes during treadmill exercise. The experimental animals were divided into 5 group - Normal(N), Control(C), 1Hour(1HR:after 1hour of glucose ingestion), 2Hour(2HR:after 2hour of glucose ingestion) and Exercise-1Hour(EX-1HR:glucose ingestion after 1 hour of preloading treadmill exercise)group - for glycogen storage study. The glycogen concentration of soleus, red gastrocnemius and plantaris muscles in N group was 4.57+/-0.34, 5.11+/-0.24 and 6.55+/-0.20 mg/gm wet wt., respectively. The glycogen concentration of soleus and red gastrocnemius in EX-1HR group were about 1.9 and 1.8 times than that of N group, respectively, but the concentration of plantaris was not higher than that of N group. The glycogen concentration of liver in N group was 41.0+/-1.47mg/gm wet wt. and the concentration of the overnight fasted C group wad only 2.9% of the value of N group. The level of glycogen concentration of liver in the other glucose ingested groups(1HR, 2HR, including EX-1HR) was within 19 - 32% of that of N group. The blood glucose concentration of EX-1HR group was higher than that of N group, the plasma free fatty acid concentration of C and 2HR group was higher than that of N group, and the plasma insulin concentration of EX-1HR group was higher than that of N group. The concentration of supercompensated glycogen of soleus and red gastrocnemius were rapidly decreased during 30 minutes of exercise but there was almost no changes of the concentration during the other 30 minutes of continuing exercise. The concentration of N group during 30 minutes of exercise was decreased but more slowly than those of EX-1HR group. The remaining level of glycogen after 60 minutes of exercise in EX-1HR group was higher than that of N group. Taken together, the mobilization of endogenous muscle glycogen at the first stage of exercise was proportioned to the intial level of glycogen concentration, and later on, when exercise continued, the muscle glycogen level was stabilized. And the remaining level of supercompensated muscle glycogen after 60 minutes of exercise was higher than that of normally stored glycogen level. The mobilization of the glycogen stroed in slow and fast oxidative muscle fibers is faster than in the fast glycolytic muscle fibers during strenous exercise.

The Charateristics of Glycogen Metabolism of Diaphragm in Rats / 영남의대학술지

Diaphragm is though to play the most role in breathing and has a substantially greater proportion of slow oxidative and fast glycolytic fibers, and low proportion of fast oxidative fibers. The respiratory muscle, diaphragm, has the functional characteristics of slow speed of contraction, high resistance to fatigue and the ability to respond to intermittent ventilatory loads, for example of exercise. In the present study, the characteristics of the metabolism (depletion and repletion) of glycogen and the structural changes of diaphragm during depletion and repletion of glycogen were observed in rats. For comparison, the red gastrocnemius muscle which has a greater proportion of fast oxidative glycolytic (FOG) and slow oxidative (SO) fibers, and low proportion of fast glycolytic (FG) fiber, was also studied. The glycogen concentration of diaphragm in overnight fasted rats was 2.30+/-0.14mg/gm wet weight. The values of glycogen concentration at 60, 90 and 120minutes of treadmill exercise loaded rats was significantly decreased compared to that of the overnight fasted rats. There was no significant difference among the glycogen concentration of diaphragm at 60, 90 and 120minutes of exercises. The glycogen concentration of diaphragm was decreased to 1.12+/-0.17 from 2.30+/-0.14mg/gm wet weight by treadmill exercise. The glycogen depletion rats of diaphragm during exercise was faster than that of red gastrocnemius in both of the first 60minutes and 120minutes duration of exercise. The glycogen repletion of diaphragm after intragastric glucose administration by stomach tube was studied in control and exercise groups. The glycogen concentration was significantly increased after glucose administration in both of the control and exercise groups. All of the concentration of exercise group at 60, 120 and 180minutes after glucose administration was significantly higher than those of control group. In conclusion, one of the characterics of diaphragm in glycogen metabolism is fast glycogen depletion during exercise, and slowness of glycogen repletion after glucose ingestion in rats.

Effect of Articular Immobilization - Induced Hindlimb Skeletal Muscle Atrophy on Autophosphorylation of Tyrosine Kinase of the Insulin Receptor in Rats / 대한정형외과학회잡지

The purpose of this study was to investigate the effects of articular immobilization-induced hindlimb skeletal muscle atrophy on the autophosphorylation of the insulin receptor tyrosine kinase in rats. Rats were divided control, and knee and ankle joint immobilized groups. The experiments were performed on the 3rd, 7th, and 21st day after the immobilization. immobilization was induced by k-wire fixation in knee and ankle joint. The ratio of soleus muscle weight to body weight was decreased in proportion to the duration of the immobilization. The glycogen content of the soleus muscle was decreased significantly (p<0.01) at the 7th day, but this value was recovered to 65% of control at the 21st day after the immobilization. The insulin bindings at various concentrations of insulin to wheat-germ agglutinin purified insulin receptor from red gastrocnemius muscle at the 7th day after immobilization were not changed compared to control. The autophosphorylation of the insulin receptor tyrosine kinase with 10-8 and 10-7 M insulin concentration at the 7th day after immobilization was decreased compared to control. In conclusion, above results showed that insulin resistance of immobilized rat hindlimb skeletal muscle was arised from defect of autophosphorylation of the insulin receptor tyrosine kinase in part.

Effect of Removal of Hindlimb Cast on Glycogen Metabolism of the Skeletal Muscle in Mice / 대한정형외과학회잡지

The purpose of this study was to determine the effect of releasing of immobilization on glycogen metabolism of hindlimb muscle after 7days use of a hindlimb casting in mice. The experimental group was divided into control group and recovery groups after removal of left hindlimb casting. The recovery groups, were subivided into the 0, 3rd and 5th day after removal of left hindlimb casting. The results were as follows; 1. The degree of atrophy of hindlimb muscles by 7 days immobilization was measured by ratio of muscle to body weight in plantaris and soleus muscles. The muscle to body weight ratios of plantaris and soleus muscles were decreased by 88% and 74%, respectively on the day of cast removal. The ratios of the both muscles were increased to the level of the control values on the 3rd and 5th day removal of casting. 2. A significant reduction of the glycogen concentration in gastrocnemius muscle occurred after 7 days hindlimb immobilization. The glycogen concentration in gastrocnemius muscle was decreased by 63% on the day of cast removal. The glycogen concentration was recovered to the values of the control group on the 3rd and 5th day after removal of hindlimb casting. 3. The level of muscle glycogen concentration of 25% glucose ingested control group was almost twice that of the normal diet control group. The muscle glycogen concentration of glucose ingested group was significantly less by 81% after 7 days of immobilization compared with the respective control gmup. The concentration recovered to the values of control on the 3rd and 5th day after removal of hindlimb casting. In contrast, there was no significant difference in the liver glycogen concentration between the immobilized grop and the cast removed group in which was removed. 4. The effects of releasing of hindlimb immobilization on plasma glucose, insulin concentration and insulin

Insulin Resistance in Late Pregnant Rats / 영남의대학술지

The influence of normal late pregnancy on insulin action and insulin secretion was studied in the Sprague-Dawley female rats. On 20th day after mating, intravenous glucose tolerance test(IVGTI) was performed in non pregnant control and pregnant rats. As results of IVGTT, glucose disappearance rate was not significantly different in both groups, but secretory response of insulin was significantly(p<0.05) increased in pregnant rat. And the ratio of insulin/ .glucose was significantly higher in pregnant rats, which means existence of insulin resistance. These insulin resistance was overcomed by increased secretory response of pancreatic insulin. Insulinogenic index( A insulin/glucose - 5 min) was highly significantly (r=0.62, p<0.01) correlated with progesterone concentration. Glycogen level and amounts of "C-glucose incorporated into glycogen after IVGTT were significantly(p<0. 05) decreased in the liver, but were not changed significantly in soleus. Glycogen synthase activity of soleus and liver was not differ significantly in the both groups. Insulin binding at varying concentrations of insulin to crude membrane of pregnant liver was not significantly different from control. In conclusions, although these pregnant rats were normal glucose tolerance due to increased secretory response of insulin, that was correlated with progesterone concentration, pregnant rat had insulin resistance. The mechanisms of insulin resistance were not related to defect of insulin binding phase and glycogen synthase, but suggest pre-receptor and/or postreceptor phase.