Human 성장호르몬을 도입한 Transgenic Rats의 작출과 번식표현형에 관한 연구 II. 형질전환된 Rats의 hGH수준이 번식표현형에 미치는 영향

장규태,김성현,성환후,주학진,박미령,윤창현 한국동물번식학회 1998 Reproductive & developmental biology Vol.22 No.2

The effects of continuous GH(hGH) secretion on the female reproduction was studies in adults female transgenic rats expressing the hGH gene with a mouse whey acid protein (mWAP) promotor. Two line of transgenic female rats carrying the mWAP/hGH gene were established and used in the study. One was characterized by relatively high levels of serum hGH (high line), and the other had relatively low levels (low line). 1. High line female rats had recurring, Pseudopregancy-like estrous cycles accompanied by increased serum progesterone level for 2 weeks after ovulation, and they were fertile. 2. In the rats, luteinization occurred spontaneously without cervical stimulation, probably due to high levels of serum hGH, which has prolactin (PRL)-like activity in the rat. 3. Low line female rats had recurring, regular 4-days estrous PRL surge following cervical stimulation were not, detected and PRL secretion was not induced by a dopamine antagonist. 4. The ovarian tissue in this line had a much higher number of corpora lutea and grew much heavier than in normal littermates, suggesting impairment of PRL induced structural luteolized. Su, pp.ession of PRL secretion in the low line rats was, at least in part, due to a marked decrease in the number of lactotrophs in the pituitary. The present study shows that the serum hGH level plays a crucial role in regulating luteal function in female transgenic rats expressing the hGH gene.

90% pancreatectomized rats 에서 w-6 다중불포화지방과 비타민 E 섭취가 인슐린 저항성에 미치는 영향

최수봉(Soo Bong Choi),박선민(Sun Min Park) 대한내과학회 1999 대한내과학회지 Vol.56 No.4

N/A High intake of -6 polyunsaturated fat (PUFA) can increase oxidative stress, which may in turn increase insulin resistance and be the cause of metabolic syndrome X (diabetes mellitus). One of the ways to reduce oxidative stress is through the consumption of antioxidants, such as vitamin E. However, it is controversial whether the consumption of vitamin E alleviates insulin resistance. The purpose of this study was to determine whether the excessive intake of -6 polyunsaturated fat and vitamin E influences the whole body glucose disposal rate (GDR), glycogen deposits in the liver and muscles, and the triglyceride content of muscles in 90% pancreatectomized rats. Methods : Mildly diabetic rats were produced by removing 90% of the pancreas from Sprague Dawley rats aged 8 weeks. One week after surgery, the blood glucose levels of rats were more than 9.4 mmol/L, according to which the rats are considered to be diabetic. Two factors were examined in the 90% pancreatectomized rats: polyunsaturated fat levels with 40% and 10% of total energy intakes, and vitamin E contents with 300 IU and 30 IU per kg of diet mixture. Four different diets were given for 8 weeks. After 7 weeks of diet consumption indwelling catheters were inserted in the carotid artery and jugular vein of all rats so that the GDR could be measured while the rats were awake and in a relaxed state. Results : Daily calorie and PUFA fat intake levels were higher in the high PUFA groups of diabetic rats. Daily vitamin E intake of the high vitamin E groups was ten times higher than that of the low vitamin E groups (p<0.0001). The GDR was lower in high PUFA groups, and the high intake of vitamin E tended to decrease the GDR in diabetic rats. The GDR of DHPHE was significantly lower than that of DLPLE (p<0.05). Sham operated rats (the control group) had a higher GDR by 44% than diabetic rats. Vitamin E deposits in the liver in DHPHE were higher in DLPLE (p<0.05). Glycogen deposits in the liver of diabetic rats were significantly higher in DLPLE than DHPLE. Muscle glycogen content showed a similar tendency to liver glycogen content in different diet groups of diabetic rats. Triglyceride deposits in muscles did not differ according to dietary fat and vitamin E contents in diabetic rats. Conclusions : High intake of -6 PUFA increased insulin resistance, and high vitamin E intake did not alleviate insulin resistance. Thus, increased oxidative stress may be an independent factor for increased insulin resistance in high intake of -6 PUFA. It is necessary to consume a minimum amount of -6 PUFA as well as the Recommended Daily Allowance of vitamin E.

Effect of Aging on the Xylene Metabolism in $CCl_4$-Induced Liver Damaged Rats

Kim, Hyun-Hee,Yoon, Chong-Guk 대한의생명과학회 2001 Journal of biomedical laboratory sciences Vol.7 No.3

To investigate an effect of aging on the xylene metabolism in liver damaged animals, a study was conducted. 50% carbon tetrachloride ($CCl_4$) in olive oil (0.1 ml/100 g body weight) was intraperitoneally given to 5-week and 12-week rats 12 times every other day and then one dose of 50% xylene in olive oil (0.25 ml/100 g body weight) was intraperitoneally given to the rats, and after 24 hr, the animals were sacrificed. On the basis of the functional findings in rat liver, ie, serum levels of alanine aminotransferase activity, liver protein and malonedialdehyde contents, 5-week rats showed less liver damage than 12-week rats. The increasing rate of urinary methylhippuric acid concentration to the control was significantly higher in 5-week rats than 12-week rats in case of xylene treatment after induction of liver damage. On the other hand, liver damaged 5-week rats showed significant rise of hepatic cytochrome P45O content compared with the liver damaged 12-week rats by the xylene treatment. And increasing rate of hepatic alcohol or aldehyde dehydrogenase activities to each liver damaged animals was higher tendency in 5-week rats than 12-week rats by the xylene treatment. In conclusion, 5-week rat showed greater metabolic rate of xylene than 10-week rats in case of liver injury because 5-week rats led to a slight liver damaged compared with 12-week rats.

Effect of Aging on the Xylene Metabolism in CCI_4-Induced Liver Damaged Rats

Kim, Hyun-Hee,Yoon, Chong-Guk 대한의생명과학회 2001 Biomedical Science Letters Vol.7 No.3

To investigate an effect of aging on the xylene metabolism in liver damaged animals, a study was conducted. 50% carbon tetrachloride (CCI_4) in olive oil (0.1 ml/100 g body weight) was intraperitoneally given to 5-week and 12-week rats 12 times every other day and then one dose of 50% xylene in olive oil (0.25 ml/100 g body weight) was intraperitoneally given to the rats, and after 24 hr, the animals were sacrificed. On the basis of the functional findings in rat liver, ie, serum levels of alanine aminotransferase activity, liver protein and malonedialdehyde contents, 5-week rats showed less liver damage than 12-week rats. The increasing rate of urinary methylhippuric acid concentration to the control was significantly higher in 5-week rats in case of xylene treatment after induction of liver damage. On the other hand, liver damaged 5-week rats showed significant rise of hepatic cytochrome P450 content compared with the liver damaged 12-week rats by the xylene treatment. And increasing rate of hepatic alcohol or aldehyde dehydrogenase activities to each liver damaged animals was higher tendency in 5- week rats than 12-week rats by the xylene treatment. In conclusion, 5-week rats showed greater metabolic rate of xylene than 10-week rats in case of liver injury because 5-week rats led to a slight liver damaged compared with 12-week rats.

STZ-당뇨쥐에서 운동부하가 골격근 및 간의 항산화효소 활성도에 미치는 영향

석광호,이석강 영남대학교 의과대학 2000 Yeungnam University Journal of Medicine Vol.17 No.1

당뇨쥐에서 운동부하가 골격근과 간의 항산화효소 활성도에 미치는 영향과 산소유리기에 의한 조직손상 여부를 관찰한 연구 결과를 요약하면 다음과 같다. Streptozotocin으로 유도한 당뇨군의 혈당농도(㎎/dL)는 344±14.8로서 대조군의 117±2.7보다 높았으며(p<0.001) 운동부하에 의해서 유의하게 감소하였다(p<0.01). 혈장 인슐린 농도(μU/mL)는 당뇨군에서 8.5±0.5로서 대조군의 20.6±1.4보다 유의하게 낮았으며(p<0.001) 운동부하후에는 운동부하전과 비교하여 차이가 없었다. 당뇨군에서 실제운동부하의 정도를 평가하기 위해서 측정한 운동부하후 골격근과 간의 당원농도(mg/100 g wet wt.)는 각각 1.0±0.1과 7.7±0.8로서 운동부하전과 비교시 모두 유의하게 감소하였다(p<0.001, p<0.01). 당뇨군의 골격근과 간의 항산화효소 즉 superoxide dismutase(SOD), glutathione peroxidase(GPX) 및 catalase(CAT)의 활성도는 운동부하에 의해서 각기 다른 반응을 보였다. 골격근의 SOD 활성도(unit/mg protein)는 대조군에서 6.3±0.2였으며 당뇨군에서는 5.8±0.2로서 대조군과의 사이에 유의한 차이를 발견할 수 없었으나 운동부하후에는 5.0±0.1로서 대조군과 운동부하전 당뇨군보다 유의하게 감소하였다(p<0.001, p<0.01). GPX 활성도(nmol/min/mg protein)는 당뇨군에서 운동부하전후에 각각 2.3±0.2와 1.8±0.1로서 대조군의 1.6±0.0보다 다같이 높았으나(p<0.05, p<0.05) 운동부하에 의해서 영향을 받지 않았다. CAT 활성도(μmol/min/mg protein)는 당뇨군에서 7.6±0.7로서 대조군의 6.3±0.7과 비교하여 차이가 없었으나 운동부하후에는 4.6±0.3으로서 대조군보다 감소하였으며(p<0.05) 당뇨군의 운동부하전보다도 감소하였다(p<0.01). 당뇨군의 MDA 농도는 대조군과 비교하여 차이가 없었으며 당뇨군에서 운동부하에 의한 영향도 받지 않았다. 간의 SOD 활성도는 대조군에서 11.3±0.2였으며 운동부하전 당뇨군에서는 9.6±0.3으로서 유의하게 감소하였다(p<0.01). 당뇨군에서 운동부하전후 측정한 SOD 활성도는 대조군과 비교하여 다같이 감소하였으나(p<0.01, p<0.001), 운동부하에 의한 영향은 없었다. 당뇨군의 GPX와 CAT의 활성도는 대조군과 비교하여 유의한 차이가 없었으며 당뇨군에서 운동 부하에 의한 변화도 없었다. 운동부하전 당뇨군의 MDA 농도(nmol/g wet wt.)는 38.5±1.3으로서 대조군의 24.8±0.9에 비해서 유의하게 증가하였으며(p<0.001) 운동부하에 의해서는 대조군보다는 높았으나(p<0.001) 운동부하전과 비교하여서는 차이가 없었다. 이상의 결과를 종합하면 당뇨쥐에서 골격근은 운동부하로 인한 산화 스트레스에 대한 적응과정을 통해서 손상이 없었으나, 간 조직은 당뇨병 자체로 인한 산소유리기의 발생으로 손상의 위험이 있었으나 운동부하에 의한 더 이상의 손상은 없었다. 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 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 until exhaution with moderate intensity (V_O2max : 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 those of 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 those 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 activity of SOD seemed to decrease slightly. 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, exhaustive physical exercise did not seem to impose oxidative stress on thee skeletal muscle because of due to oxygen free radicals, regardless of the decrease in 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 exhaustive physical exercise was not observed.

Involvement of Nuclear Related Factor 2 Signaling Pathway in the Brain of Obese Rats and Obesity-Resistant Rats Induced by High-Fat Diet

Weiwei Ma,Bingjie Ding,Li-Jing Wang,Yi Shao,Rong Xiao 한국식품영양과학회 2016 Journal of medicinal food Vol.19 No.4

We aimed to investigate the mechanism of brain damage in diet-induced obese (DIO) rats and diet-resistant (DR) rats from the viewpoint of redox state and nuclear related factor 2 (Nrf2) signaling pathway. Sprague-Dawley rats were fed with a high-fat diet for 10 weeks to obtain the DIO and DR rats. d-Galactose was injected subcutaneously through the back of the neck for 10 weeks to establish oxidative stress model rats. Then, the ratio of reduced glutathione (GSH)/oxidized glutathione (GSSG) and the level of glutathione peroxidase (GSH-Px) in serum and brain tissue were measured by using enzymatic assay kits. The levels of cholecystokinin and peptide YY in the brain tissue were detected by using enzyme-linked immunosorbent assay kits. In addition, the protein expression of Nrf2 and its downstream factors such as heme oxygenase 1, manganese superoxide dismutase, and NAD(P)H quinone oxidoreductase 1 (NQO1) in the brain tissue were measured by Western blotting. In the brain of DIO rats, the level of GSH and ratio of GSH/GSSG were lower, whereas the GSH-Px concentration was higher compared with DR rats significantly. On the other hand, the GSSG level was higher in the serum of DIO rats compared with the DR rats. The oxidative stress state in the brain of DIO rats, but not in DR rats, were observed. In addition, the protein expressions of Nrf2 and NQO1 were downregulated in the brain of DR rats compared with that in DIO rats. Our data suggest that the Nrf2/NQO1 signaling pathway and redox state were involved in the pathogenesis of the rats prone to obesity, but not the DR rats resistant to obesity.

반복적인 금식으로 인한 렙틴 농도 변동이 렙틴 감수성에 미치는 영향

박성철,박용훈,박소영,김종연,박윤기,이태형,원규장,김용운 대한내분비학회 2008 Endocrinology and metabolism Vol.23 No.5

Background: Leptin resistance is a common feature in obese subjects and animals, and this is commonly accompanied with hyperleptinemia. We speculated that one of the causes of leptin resistance is a persistently elevated leptin concentration and then we hypothesized that fluctuations of serum leptin would increase leptin sensitivity in the leptin-resistant state. Methods: We used a repeated fasting and refeeding (RFR) protocol to produce fluctuation in leptin levels in 7 month-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats, We then measured the leptin sensitivity following an intracerebroventricular (i.c.v.) infusion of leptin. Results: The OLETF rats exhibited severe visceral fat deposition, hyperleptinemia and leptin resistance. However, in the OLETF-RFR rats, the anorexic effect following i.c.v. leptin infusion was restored. Moreover, the visceral fat mass and serum leptin levels decreased, while the serum adiponectin levels were elevated in the OLETF-RFR rats compared to the OLETF-Control rats. The leptin receptor content in the hypothalamus increased in the OLETF-RFR rats compared to the OLETF-Control rats, and the leptin receptor content in the OLETF-RFR rats decreased compared to that in the the LETO-Control rats. Conclusions: These results suggest that the intermittent suppression of the serum leptin level reversed the leptin resistance in OLEFT rats, and this may have occurred due to an increased number of leptin receptors in the hypothalamus. Background: Leptin resistance is a common feature in obese subjects and animals, and this is commonly accompanied with hyperleptinemia. We speculated that one of the causes of leptin resistance is a persistently elevated leptin concentration and then we hypothesized that fluctuations of serum leptin would increase leptin sensitivity in the leptin-resistant state. Methods: We used a repeated fasting and refeeding (RFR) protocol to produce fluctuation in leptin levels in 7 month-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats, We then measured the leptin sensitivity following an intracerebroventricular (i.c.v.) infusion of leptin. Results: The OLETF rats exhibited severe visceral fat deposition, hyperleptinemia and leptin resistance. However, in the OLETF-RFR rats, the anorexic effect following i.c.v. leptin infusion was restored. Moreover, the visceral fat mass and serum leptin levels decreased, while the serum adiponectin levels were elevated in the OLETF-RFR rats compared to the OLETF-Control rats. The leptin receptor content in the hypothalamus increased in the OLETF-RFR rats compared to the OLETF-Control rats, and the leptin receptor content in the OLETF-RFR rats decreased compared to that in the the LETO-Control rats. Conclusions: These results suggest that the intermittent suppression of the serum leptin level reversed the leptin resistance in OLEFT rats, and this may have occurred due to an increased number of leptin receptors in the hypothalamus.

Subrenal Capsule Assay를 이용한 흰쥐와 Zucker 비만쥐에 폐암세포주 이식의 효과

이동석,김송명,김종인,변정훈 고신대학교 의학부 2005 高神大學校 醫學部 論文集 Vol.20 No.1

The effects of lung cancer cell line in Spague Dowley rats and Zucker's obese rats using subrenal capsule assay. Background/Purpose: Lung cancer is well known as one of the high malignant cancer. So far many clinical trials of multimodality treatment consisted of chemotherapy, radiotherapy and surgery were performed, but the results showed quite difference according to the authors and the 5-year survival rate is still dismal. Presently the subrenal capsule assay is regarded as the best method to assess anticancer chemosensitivity and it's importance is increasing gradually. Recently, obesity due to overnutrition and underexercise has been increased. In this study, we evaluated of the tumor growth and the differences of cancer chemosensitivity after human lung cancer cell implantation between Spargue Dowley rats and Zucker obese rats. Material and Method: Human lung cancer cells(SW-900 G Ⅳ) were cultured on the RPMI 1640 media which contains fetal cow serum and fibrin clot which contains 107 cancer cells(2×2×2mm3). Those cultured cells were implanted to a S.D rats were implanted to a S.D rats and a Zucker obese rats. Group Ⅰ and group Ⅱ were S.D rats and group Ⅲ and group Ⅳ were Zucker obese rats. From the first day to sixth day of implantation, cyclosporin-A(80mg/㎏) was given subcutaneously for immunosuppression. GroupⅠand Ⅲ were given for normal saline, groupⅢ and group Ⅳ were given for NIC (Navelbine 10㎎/㎏, Ifosfamide 30㎎/㎏, measured before and after the implantation. Implanted tumor size and it's histological findings were evaluated and the results of each group were compared. Result: Because of the NIC chemotherapy, group Ⅱ showed loss of the body weight, but group Ⅳ was not affected by the chemotherapy relative and the body weight increased slowly by rat's age. The blood glucose level of each groups were within normal range. But its level of group Ⅱ was less than group Ⅰ by 23㎎%, but group Ⅲ and Ⅳ have similar glucose level which means those two groups were not affected much by the cancer chemotherapy. The growth of implated cancer cells in Zucker obese rats was slow than in S.D. rats. The cancer cell growth of S.D rats was not inhibited by chemotherapy, but chemotherapy influenced to the cancer cell low in group Ⅲ and Ⅳ. Apoptosis were found in group Ⅱ, Ⅳ. All of groups revealed mild inflammation and fibroblasts were observed in group Ⅰ, Ⅲ. Conclustion: This study demonstrates that subrenal capsule assay can be used to determine the response of human lung cancer cell to various combinations of chemotherapeutic agents. And the subrenal capsule assay can be done for the chemosensitivity test for lung cancer cells in short time. In the Zucker obese rats, we certified that meatbolic state related to obesity influenced to human lung cancer cell growth.

Subrenal Capsul Assay를 이용한 흰쥐와 Zucker 비만쥐에 폐암세포주 이식의 효과

이동석,김송명,김종인,변정훈 고신대학교(의대) 고신대학교 의과대학 학술지 2005 고신대학교 의과대학 학술지 Vol.20 No.1

The effects of lung cancer cell line in Spague Dowley rats and Zucker's obese rats using subrenal capsule assay. Background/Purpose : Lung cancer is well known as one of the high malignant cancer. So far many clinical trials of multimodality treatment consisted of chemotherapy, radiotherapy and surgery were performed, but the results showed quite difference according to the authors and the 5-year survival rate is still dismal. Presently the subrenal capsule assay is regarded as the best method to assess anticancer chemosensitivity and it's importance is increasing gradually. Recently, obesity due to overnutrition and underexercise has been increased. In this study, we evaluated of the tumor growth and the differences of cancer chemosensitivity after human lung cancer cell implantation between Sprague Dowley rats and Zucker obese rats. Materials and Method : Human lung cancer cells (SW-900G 4) were cultured on the RPMI 1640 media which contains fetal cow serum and fibrin clot which contains 107 cancer cells (2x2x2mm3). Those cultured cells were implanted to a S.D rats were implanted to a S.D rats and a Zucker's obese rates. Group 1 and group 2 were S.D rats and group 3 and group 4 were Zucker obese rats. From the first day to sixth day of implantation, cyclosporin-A (80mg/kg) was given subcutaneously for immunosuppression. Group 1 and 3 were given for normal saline, group 3 and group 4 were given for NIC (Navelbine 10mg/kg, Ifosfamide 30mg/kg, Cis-Platinum 1mg/kg) chemotherapy for 6 days after tumor cell implantation. Body weight and blood glucose level were measured before and after the implantation. Implanted tumor size and it's histological findings were evaluated and the results of each groups were compared. Result : Because of the NIC chemotherapy, group 2 showed loss of the body weight, but group 4 was not affected by the chemotherapy relatively and the body weight increased slowly by rat's age. The blood glucose level of each groups were within normal range. But its level of group 2 was less than group 1 by 23mg%, but group 3 and 4 have similar glucose level which means those two groups were not affected much by the cancer chemotherapy. The growth of implanted cancer cells in Zucker obese rats was slow than in S.D rats. The cancer cell growth of S.D rats was not inhibited by chemotherapy, but chemotherapy influenced to the cancer cell growth in Zucker obese rats. In the histologic findings, malignant potency was relatively hihgh in group 1 and 2, but low in group 3 and 4. Apoptosis were found in group 2,4. All of groups revealed mild inflammation and fibroblasts were observed in group 1,3. Conclusion : This study demonstrates that subrenal capsule assay can be used to determine the response of human lung cancer cell to various combinations of chemotherapeutic agents. And the subrenal capsule assay can be done for the chemosensitivity test for lung cancer cells in short time. In the Zucker obese rats, we certified that metabolic state related to obesity influenced to human lung cancer cell growth.

The Preventive Effects of 8 Weeks of Resistance Training on Glucose Tolerance and Muscle Fiber Type Composition in Zucker Rats

Kim, Ji-yeon,Choi, Mi Jung,So, Byunghun,Kim, Hee-jae,Seong, Je Kyung,Song, Wook Korean Diabetes Association 2015 Diabetes and Metabolism Journal Vol.39 No.5

<P><B>Background</B></P><P>We investigated the therapeutic effects of resistance training on Zucker rats before and after the onset of diabetes to understand the importance of the timing of exercise intervention. We assessed whether 8 weeks of resistance training ameliorated impaired glucose tolerance and altered muscle fiber type composition in Zucker rats.</P><P><B>Methods</B></P><P>Five-week-old male Zucker rats were divided into Zucker lean control (ZLC-Con), non-exercised Zucker diabetic fatty (ZDF-Con), and exercised Zucker diabetic fatty (ZDF-Ex) groups. The ZDF-Ex rats climbed a ladder three times a week for 8 weeks. Intraperitoneal glucose tolerance tests (IPGTT) were performed on the 1st and 8th weeks of training, and grip strength was measured during the last week. We also measured glucose transporter 4 (GLUT4) expression by Western blot and immunofluorescence. Moreover, immunohistochemistry was performed to assess muscle fiber type composition.</P><P><B>Results</B></P><P>Fasting glucose levels and area under the curve responses to IPGTTs gradually increased as diabetes progressed in the ZDF-Con rats but decreased in the ZDF-Ex rats. Grip strength decreased in the ZDF-Con rats. However, resistance training did not improve grip strength in the ZDF-Ex rats. GLUT4 expression in the ZLC-Con and the ZDF-Con rats did not differ, but it increased in the ZDF-Ex rats. The proportions of myosin heavy chain I and II were lower and higher, respectively, in the ZDF-Con rats compared to the ZLC-Con rats. Muscle fiber type composition did not change in the ZDF-Ex rats.</P><P><B>Conclusion</B></P><P>Our results suggest that regular resistance training initiated at the onset of diabetes can improve glucose tolerance and GLUT4 expression without changing muscle morphology in Zucker rats.</P>