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

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.

体内雌性性激素水平降低会损伤血管内皮功能，进而引发与特定疾病相关的血管功能障碍。卵巢切除术动物模型常被用于探究其对血管（功能）异常的影响。傅里叶变换红外（Fourier-transform infrared, FTIR）光谱技术可提取精细的分子信息，因此已被应用于各类生物学分析。本研究采用中红外光谱技术评估卵巢切除模型的系统性分子变化。本研究共分析38份成年Wistar大鼠的血清样本，将其分为假手术组（SHAM，18份）与卵巢切除组（OVX，20份）。实验实施双侧卵巢切除术，术后15天对大鼠实施安乐死。采用德国布鲁克公司的Bruker Alpha II设备完成光谱采集，借助MATLAB 2023软件对光谱数据进行预处理，并分别采用无监督分析方法——主成分分析（PCA），以及有监督分析方法——偏最小二乘判别分析（PLS-DA）开展数据分析。针对主成分分析模型，本研究对主成分（PC）1至4的各类组合进行了测试，但所有PC组合均无法清晰区分OVX组与SHAM组。偏最小二乘判别分析模型的灵敏度为66%、特异度为80%，假阳性率为20%，假阴性率为33%，F值为0.727，准确率为72.7%。然而，y置换检验结果显示，该分析结果为随机产生的结果。上述结果表明，针对接受15天卵巢切除术的大鼠，采用中红外光谱技术分析其系统性分子谱时，未发现两组间存在显著差异。