# Infrared Spectroscopy Coupled with Machine Learning Algorithms to Investigate Vascular Dysfunction in Ovariectomy: An Animal Model Study

## TL;DR

This study used infrared spectroscopy and machine learning to examine vascular changes in ovariectomized rats but found no significant differences after 15 days.

## Contribution

The novelty lies in applying mid-infrared spectroscopy with machine learning to analyze systemic changes in an ovariectomy animal model.

## Key findings

- PCA analysis failed to distinguish between ovariectomized and control groups.
- PLS-DA showed moderate accuracy but results were deemed random via permutation tests.
- No significant systemic profile differences were detected in ovariectomized rats after 15 days.

## Abstract

A decrease in female
sex hormone levels in the body impairs vascular
endothelium functioning, leading to vascular dysfunction associated
with certain diseases. Animal models of ovariectomy are commonly used
to understand its effects on vascular (dys)function. Fourier-transform
infrared (FTIR) spectroscopy is a technique capable of extracting
detailed molecular information and, as such, has been applied to various
biological analyses. This study evaluated systemic changes in the
ovariectomy model using mid-infrared spectroscopy. Thirty-eight serum
samples from adult Wistar rats were analyzed and divided into 18 in
the control group (SHAM) and 20 in the ovariectomized group (OVX).
Bilateral ovariectomy was performed, followed by euthanasia of the
rats after 15 days. The spectral collection was performed using the
Bruker Alpha II equipment (Bruker, Germany), preprocessed, and analyzed
using unsupervised analysis methods [principal component analysis
(PCA)] and supervised analysis methods [partial least-squares discriminant
analysis (PLS-DA)] (MATLAB 2023). For the PCA model, combinations
between principal components (PCs) 1 to 4 were performed. Nevertheless,
none of the PC combinations allowed a clear distinction between the
OVX and SHAM groups. The PLS-DA model exhibited 66% sensitivity, 80%
specificity, a false positive rate of 20%, and a false negative rate
of 33%. The F-score was 0.727 and the accuracy was 72.7%. However,
the y-permutation test demonstrated that this result
was random. These results indicate that there is no significant difference
in the systemic profile of rats subjected to ovariectomy surgery for
15 days when analyzed using mid-infrared spectroscopy.