Effects of Metformin on Penile Expression of Nitric Oxide Synthase in OLETF Rats

PURPOSE: It is well known that metformin, an oral biguanide insulinsensitizing agent, targets AMP-activated protein kinase (AMPK), which activates endothelial nitric oxide synthase (eNOS), which may be associated with erectile dysfunction. The aim of this study was to evaluate whether metformin activates eNOS in the penile tissue of a genetically obese rat model. MATERIALS AND METHODS: We measured phospho-eNOS levels and eNOS expression in the penile tissue of Otsuka Long Evans Tokushima Fatty (OLETF) rats after 3 days of treatment with metformin (150 or 300 mg) to evaluate whether metformin activates eNOS in the penile tissue of this genetically obese rat model. Seven-month-old OLETF rats were used, and eNOS expression was analyzed by real-time polymerase chain reaction (PCR). The experimental groups were compared with use of the Kruskal-Wallis or Mann-Whitney test. RESULTS: Seven-month-old OLETF rats had severe visceral fat deposition and elevated serum leptin concentrations. eNOS expression analyzed by real-time PCR was lower in the penile tissue of OLETF rats than in Long Evans Tokushima Otsuka (LETO) rats. Short-term treatment with metformin did not change visceral fat mass or serum leptin levels. However, metformin treatment increased eNOS mRNA expression in the penile tissue as determined by real-time PCR. The levels of phospho-eNOS and phospho-AMPK (pAMPK) in penile tissue revealed a dose-dependent tendency to increase with metformin treatment; however, there was no statistical difference by Kruskal-Wallis test among the experimental groups. The pAMPK level was dose-dependently elevated in the soleus by metformin treatment. There was no significant change in pSTAT3 by metformin treatment in the soleus. CONCLUSIONS: Metformin activates eNOS mRNA expression in the penile tissue of OLETF rats. Further study on the relation between erectile function and eNOS levels is needed for clinical application.

Expression Analysis of c-IAP2 in Ovarian Carcinomas / 대한산부인과학회잡지

OBJECTIVE: Apoptosis or programmed cell death is a normally physiological cell suicide program that is highly conserved among all animals. We previously evaluated overexpression of c-IAP1(Inhibitor of Apoptosis Protein) in ovarian carcinomas compared with normal ovaries. In this study, we demonstrate evidence for the involvement of c-IAP2 in ovarian carcinomas. METHODS: Fresh 9 normal ovaries, 5 benign ovarian cysts and 13 ovarian carcinomas were obtained from routine gynecologic surgeries carried out for benign and malignant ovarian tumors. They were examined for the presence of c-IAP2 by RT-PCR(Reverse Transcriptase Polymerase Chain Reaction), Western blot analysis and immunohistochemical stains. RESULTS: Nine of 14 normal and benign ovarian tumors were negative and 11 of 13 ova rian carcinomas were positive for c-IAP2 by RT-PCR. Positive RT-PCR for c-IAP2 was seen in 11/13 of ovarian carcinomas, a significantly higher percentage than in normal and benign ovarian tumors(5/14). All of these tumors showed strong positive for c-IAP2 by western blot and immunohistochemical staining. Whereas negative RT-PCR for c-IAP2 was seen in 9/14 of normal and benign ovarian tumors, a significantly higher percentage than ovarian carcinomas(2/13). Of these 9 negative samples, 6 had positive Western blot and immunohistochemical stains. There was weak concordance of the result. But expression of c-IAP2 in normal ovarian tissue was localized exclusively in the corpus luteum. Therefore, c-IAP2 may play important role in determining the fate of the follicular destiny. There was no expression in normal ovarian stroma cells for c-IAP2. CONCLUSIONS: These findings suggest that c-IAP2 is expressed in ovarian carcinomas and emerging role in cancer. The c-IAP2 expression has been investigated in the normal ovary, where apoptosis is thought to play an important role in ovulation.

The Change of Serum Level of Xanthine Oxidase Activity, Glutathione and Malonyldialdehyde following Renal Ischemia/Reperfusion Injury in the Rat / 대한비뇨기과학회지

PURPOSE: It has been suggested in our previous study that the level of xanthine oxidase(XO) activity, glutathione(GSH) and malonydialdehyde(MDA) in renal tissue following renal ischemia/reperfusion(I/R) could be used as marker of oxidant stress. Present study was undertaken to investigate the serum level of XO activity. GSH and MDA following renal I/R and to elucidate potential use of the serum level of GS H and MDA as makers of renal function following I/R injury. MATERIALS AND METHODS: Male Sprague-Dawley rats(200-250gm) were divided into 3 groups : group A - occlusion of bilateral renal arteries for 60 min, group B - pretreatment allopurinol(20mg/Kg). a radical scavenger, plus occlusion of renal arteries, and group C(control group) - sham operation. In group A and B, recirculation of renal arteries were performed for 30min. XO activity, xanthine dehydrogenase(XD) type conversion ratio, level of GSH and MDA were measured from venous blood. RESULTS: Both XO activity(nM/mg/min) and XD type conversion ratio(%) were increased in group A(XO; 0.173+/-0.012, XD; 60.44+/-4.32) and decreased in group B(XO; 0.136+/-0.01, XD; 45.40+/-4.78) compared to control group(XO; 0.153+/-0.012, XD; 46.93+/- 3.45). The level of GSH(microM/g tissue), a scavenger of oxygen free radical(OFR), was also decreased in group A(0.130+/-0.021) compared to group B(0.179+/-0.021) and control group(0.186+/-0.017). In addition, the level of MDA(nM/g tissue), which is a stable end product of lipid peroxidation, was significantly increased in group A(0.076+/-0.006) compared to group B(0.057+/-0.005) and control group(0.053+/-0.004). CONCLUSIONS: From these results, it is suggested that renal I/R injury is highly correlated with the production of OFR. Furthermore. the serum levels of MDA and GSH might be used as early markers of oxidant stress in association with renal I/R injury.

Effect of Deferoxamine on Renal Function following Renal Ischemia/Reperfusion in the Rat / 대한비뇨기과학회지

PURPOSE: It has been suggested in our previous study that the serum level of xanthine oxidise(XO) activity, glutathione(GSH), malonyldialdehyde(MDA) could be used as marker of oxidant stress in association with renal ischemia/reperfusion(I/R) injury. The present study was undertaken to establish the early marker of renal 1/R injury and to investigate the effect of deferoxamine on renal 1/R injury. MATERIALS AND METHOD: In Sprague-Dawley rats(male, 200-250gm, n=60), bilateral renal arteries were clamped for 60mins after pretreatment with deferoxamine(group A) or saline(group B). After 30min of bilateral renal recirculation, left nephrectomy and blood sampling in inferior vena cava were performed for in-vitro spectrophotometric study. Control animals(group C) did not undergo I/R operation. In-vivo renal function studies were performed in both group A and B with measurement of creatinine clearance rate(Ccr) at 7th day of experiments a%or renal ischmia for 60min. RESULTS: The levels of XO activity and XO type conversion ratio in renal tissue (RT) and serum(5) were measured. These levels were significantly high in group B, but were lower in group A compared to those of control group. The values of GSH(micrometer/g tissue), a scavenger of OFR, were decreased in group A (RT:0.183+/-0.019,5:0.201+/-0.029) and greatly decreased in group B(RT:0.159+/-0.009,5:0.164+/-0.022) compared to control group(RT:0.201+/-0.006,5:0.224+/-0.031). The values of MDA(nM/g tissue), a stable end product of lipid peroxidation, were increased in group A(RT:0.149+/-0.003, 5:0.058+/-0.004) compared to control group(RT:0.128+/-0.013, 5;0.055+/-0.005), but the values were significantly lower in group A compared to group B(RT:0.171+/-0.005, 5:0.070+/-0.003). Subsequent investigation was focused on the established renal function study after 1/R, which was determined using Ccr(ml/min). The Ccr in group A(2.06+/-0.03) was significantly higher compared to that of group 8(1.48+/-0.18), although it was slightly lower than in control group(2.18+/-0.05). CONCLUSIONS: From these results, it is suggested that renal I/R injury is highly correlated with the production of OFR. The levels of GSH and MDA in renal tissue and serum seem to be probable markers of oxidant stress in association with renal I/R injury. Furthermore, deferoxamine could reduce the degree of renal damage resulting from ameliorating the production of OFR following renal I/R injury.