Antihyperglycemic effect of fraxetin on hepatic key enzymes of carbohydrate metabolism in streptozotocin-induced diabetic rats
Authors: Subramani Srinivasan
Natarajan Ashokkumar
Raju Murali
Journal: Biochimie (2013)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: Diabetes mellitus; Fraxetin; Glucose; Streptozotocin.
Affiliations: Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar 608002, Tamilnadu, India.

Abstract:  Epidemiological studies have demonstrated that the diabetes mellitus is a serious health burden for both governments and healthcare providers. The present study was hypothesized to evaluate the antihyperglycemic potential of fraxetin by determining the activities of key enzymes of carbohydrate metabolism in streptozotocin (STZ) - induced diabetic rats. Diabetes was induced in male albino Wistar rats by intraperitoneal administration of STZ (40 mg/kg b.w). Fraxetin was administered to diabetic rats intra gastrically at 20, 40, 80 mg/kg b.w for 30 days. The dose 80 mg/kg b.w, significantly reduced the levels of blood glucose and glycosylated hemoglobin (HbA1c) and increased plasma insulin level. The altered activities of the key enzymes of carbohydrate metabolism such as glucokinase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase and hepatic enzymes (aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP)) in the liver tissues of diabetic rats were significantly reverted to near normal levels by the administration of fraxetin. Further, fraxetin administration to diabetic rats improved body weight and hepatic glycogen content demonstrated its antihyperglycemic potential. The present findings suggest that fraxetin may be useful in the treatment of diabetes even though clinical studies to evaluate this possibility may be warranted. 

Retracted: No

PubPeer comments:
 Is seems that there is a duplication in some of the  representative Ponceau S stainings : Figure 3a: ![file] Figure 6: ![file] Figure 6: ![file] Figure 8a: ![file] Figure 9a: ![file] Given the pattern of protein migration I d bet that the Ponceau S shown is actually only representative for the experiments shown in figure 9 and perhaps the NRF1 panel of figure 6. Could the authors please check? , 
 Another duplication: Figure 11E: ![file] Figure 12E: ![file] Given the splice in Figure 11E I would expect the splice to be present in the matched representative loading as well. , 
 Dear Penicillium Subspinulosum, Thank you for taking the time to read our manuscript. It seems that you have some questions about repeated presentation of some PonceauS images used in our publication. We have indeed reused PonceauS images in case multiple targets originate from the same membrane and, therefore, should be corrected with the same corresponding PonceauS quantification. We hereby would like to address your concerns in more detail. First of all it is important to understand that all quantifications of Western blot signals depicted in this manuscript were performed on original images and that each quantification was corrected for the complete length of PonceauS staining specific for the corresponding sample and membrane. Due to the high number of samples and measurements included in this manuscript, only representative images were shown in the Western blot panels accompanying the quantifications. In more detail, after the membranes were blotted, a PonceauS incubation and imaging step was performed on the entire membrane, and total protein loading was quantified over the entire length of the membrane. At the end of this response, we included the image of the entire length of the PonceauS stain that was used in the panel with representative images in Fig 3, 6, 8 and 9. Only a representative part of the PonceauS image was shown in the publication to keep the panels concise (boxed in Red in the image below). After the PonceauS staining, the membranes were divided in several horizontal strips using the molecular weight marker to ensure that respective target will be on that strip. Each strip thus contains all samples, and the respective targets were measured on these strips, in the end resulting in multiple measured targets per membrane. In some specific cases (e.g. BNIP3 and OXPHOS), multiple targets were measured on one strip, either after re-probing the strip with a second antibody or by removal of the fist antibody by a stripping step. Because multiple targets originated from the same membrane, they were all corrected with the same corresponding PonceauS quantification. Part #1: Penicillium Subspinulosum points out duplications of the PonceauS image in Fig 3, 6 (2x), 8 and 9. The two PonceauS images that Penicillium Subspinulosum copied from Fig 6 are actually two different images (differences can clearly been seen in e.g. lane 3 and lane 5 as well as the relative differences between lane 7 and 8 between these 2 PonceauS stainings). The other indicated images (i.e. the image from Fig 3, the second image from Fig 6, and the images from Fig 8 and Fig 9) are indeed the same because these targets were actually all measured on the exact same membrane, as explained above. It is possible that Penicillium Subspinulosum also refers to the right side of the PonceauS staining which slightly curls up, a pattern which is not visible in all the indicated images of the proteins of interest. The reason for this is simple: the migration pattern indeed curled up in the low range of the membrane, but to a much lesser extend in the high range of the membrane as can be clearly seen in the included image of the complete PonceauS-stained membrane below. Thus, proteins with a higher molecular mass were less affected by this migration pattern. Part #2: All the representative images (both target protein and PonceauS) in Fig 11E, 11F, 12E, 13C, 13H are from the exact same four samples, except for the representative images from PARK2 due to an artifact (see explanation below). Although the depicted proteins that were grouped in the panels (Fig 11E, 11F, 12E, 13C, 13H) were not necessarily ran on the same membrane, we have chosen to show only one representative PonceauS image (originating from a membrane that supplied at least one of the depicted targets) per panel to keep the panels concise. For the same reason as indicated above (multiple targets measured on the same membrane), the representative PonceauS image shown in Fig 11E and 12E is indeed identical. Regarding PARK2: Because the PARK2 image showed an artifact on the samples that were used for all the other representative images in Fig 11E, 11F, 12E, 13C, 13H, an image of different representative samples had to be depicted for PARK2 protein only. For transparency reasons, we actually indicated this by the black vertical separator line in Fig 11E (for the PARK2 lanes). Therefore, **only for PARK2**, the PonceauS image and the PARK2 image are not from the exact same samples. Since the PonceauS that belonged to the PARK2 samples did not show any different expression levels compared with the representative PonceauS image that was already included, we chose not to include a separate representative PonceauS image for PARK2 only. We value your critical reading of our manuscript, and hope these clarifications address the concerns that were expressed. Best regards, On behalf of the authors, Pieter A. Leermakers ![file] ,