Effect of two physical exercise protocols on the behavior of Clusterin protein in obese mice

Author(s)

Chadi Pellegrini Anaruma

• Document type: Doctoral Thesis
• Press: Rio Claro. 2020-11-23.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2020-09-11
• Advisor: Leandro Pereira de Moura

Abstract

Introduction: Recently related to insulin signaling, clusterin (CLU) protein can be found in several tissues as well in serum. It is known that physical exercise plays a positive role in insulin pathway. However, till the date, is unknown the effect of exercise in CLU levels. Objective: We investigated the effect of short-term training in glucose homeostasis and muscular CLU levels in obese mice. Methods: Study protocol was approved by ethics committee nº 4773- 1/201. Swiss mice were divided into four groups: CTS (n=12): fed with chow diet and; OBS (n=12), OBA (n=12) and OBF (n=12): fed with high fat diet (60% Kcal fat), for 14 weeks. The OBA group underwent one-hour treadmill aerobic exercise at 75% Pmax for seven consecutive days. The OBF group underwent 20 climbing on stairs at 75% MVCC for seven consecutive days. Mice were euthanized and skeletal muscle (gastrocnemius) was excised for protein content and RNAm analyses. Data are presented as mean±S.E.M.. Comparisons between groups were done using ANOVA one-way followed by Tukey post hoc test. Correlation coefficients were calculated using Pearson or Spearman’s test. P<0.05 was considered statistically significant. Results: Obese mice presented worsened glucose homeostasis and insulin signaling compared with CTS, which was improved by the short-term training (STT) in treadmill. Serum insulin levels were increased in OBS compared with CTS as well as HOMAIR, STT was efficient in improving both parameters. STT improved insulin signaling in OBA compared with CTS and OBS. The HFD was not able to increase CLU skeletal muscle levels, however the STT increased CLU levels in 143% vs CTS and 121% vs OBS. Insulin stimulus increased CLU. Insulin increased CLU levels by 37% in OBS compared with CTS and STT reduced its levels significantly. CLU gene expression increased 172% and 114% in OBA skeletal muscle compared with CTS and OBS, respectively. CLU protein levels positively correlated with physiologic parameters, among than, fasting blood glucose (r=0.60; p=0.04), serum insulin (r=0.70; p=0.01) and HOMA-IR (0.72; p=0.007). Glucose homeostasis was also improved by the STT in stairs. Fasting blood glucose levels were increased in OBS compared with CTS as well as serum insulin. STT was efficient in improving both parameters, but no changes were found in HOMA-IR. During the ipITT, the group OBF presented reduction in AUC and blood glucose decay improved by 62% when insulin-stimulated. No differences were found in muscle CLU protein content and gene expression between groups, however, the STT was able to increase LRP2 protein levels in skeletal muscle. Conclusion: According to data presented, we concluded that clusterin plays an important role on glucose homeostasis due to its correlation with several physiologic parameters as well as be modulated by insulin stimulus. Additionally, we are the first study about the effect of STT in skeletal muscle CLU levels and here we showed that STT improved insulin signaling in obese mice skeletal muscle but only the treadmill STT was able to modulated CLU protein and mRNA levels in obese mice skeletal muscle regardless of body weight changes. (AU)

• FAPESP's process: 16/14388-9 - Comparison of two exercise protocols on action mechanism of clusterin/ApoJ in lean and obese mice
• Grantee: Chadi Pellegrini Anaruma
• Support Opportunities: Scholarships in Brazil - Doctorate