EXPRESS: Raman Spectroscopy for Adipose Tissue Assessment in a Rat Model of Obesity and Type 1 Diabetes.

The adipose tissue presents structural and functional changes in obesity and type 1 diabetes (T1DM). In obesity, the size and number of adipocytes and the adipokines' secretion increase. In T1DM, a loss of adipose tissue suggests changes in the metabolic activity of this tissue. A significant challenge is to find alternative non-invasive methods to evaluate molecular changes in adipose tissue related to obesity and T1DM. Recently, Raman spectroscopy and chemometrics techniques have emerged as an alternative tool for biological tissue analysis. In this work, we propose the use of Raman spectroscopy to characterize spectral differences in adipose tissue from different rat groups (control, obese, and T1DM). The Raman spectra were analyzed using direct band analysis, ratiometric analysis, and chemometrics (principal component analysis and support vector machines). We found that the Raman spectra of obese rats showed significant spectral differences compared to control and diabetic groups related to fatty acids Raman bands. Also, the obese group has a significant decrease in the degree of unsaturation of lipids. The PCA-SVM model showed classification performance ranging from 71.43% to 71.79% accuracy for brown and white adipose tissue samples, respectively. In conclusion, the results show that Raman spectroscopy can be used as a non-destructive method to assess adipose tissue according to a metabolic condition.