Integrative Analysis of Vaginal Microorganisms and Serum Metabolomics in Rats With Estrous Cycle Disorder Induced by Long-Term Heat Exposure Based on 16S rDNA Gene Sequencing and LC/MS-Based Metabolomics

Abstract

Long term heat exposure (HE) leads to estrous cycle disorder (ECD) in female rats and damages reproductive function. However, the regulation mechanism of vaginal microorganisms and serum metabolomics remains unclear. This study aimed to explore the effects of microbes on the vaginal secretions of rats with ECD and describe the serum metabolomics characteristics and their relationship with vaginal microorganisms. The alterations in the serum levels of neurotransmitters were used to verify the possible regulatory pathways. The relative abundance, composition, and colony interaction network of microorganisms in the vaginal secretions of rats with ECD changed significantly. The metabolomics analysis identified 22 potential biomarkers in the serum including lipid metabolism, amino acid metabolism, and mammalian target of rapamycin and gonadotropin-releasing hormone (GnRH) signaling pathways. Further, 52 pairs of vaginal microbiota–serum metabolites correlations (21 positive and 31 negative) were determined. The abundance of Gardnerella correlated positively with the metabolite L-arginine concentration and negatively with the oleic acid concentration. Further, a negative correlation was found between the abundance of Pseudomonas and the L-arginine concentration and between the metabolite benzoic acid concentration and the abundance of Adlercreutzia. These four bacteria–metabolite pairs had a direct or indirect relationship with the estrous cycle and reproduction. The glutamine, glutamate, and dopamine levels were significantly uncontrolled. The former two were closely related to GnRH signaling pathways involved in the development and regulation of HE-induced ECD in rats. Serum neurotransmitters partly reflected the regulatory effect of vaginal microorganisms on the host of HE-induced ECD, and glutamatergic neurotransmitters might be closely related to the alteration in vaginal microorganisms. These findings might help comprehend the mechanism of HE-induced ECD and propose a new intervention based on vaginal microorganisms.

Heat Stress Altered the Vaginal Microbiome and Metabolome in Rabbits

“…Surprisingly, in this study, the relative abundance of Firmicutes decreased in the Heat group while the relative abundance of Actinobacteria and Proteobacteria increased ( Ceccarani et al, 2019 ). Corynebacterium , one of the dominant genera in rabbit vagina, increased its relative abundance in the Heat group, which is consistent with a previous study that demonstrated an increase in the abundance of Corynebacterium in rat vagina after heat-stress treatment ( An et al, 2021 ). It has been suggested that Fusobacterium is one of the most abundant genera in cows ( Santos et al, 2011 ; Jeon et al, 2015 ) and canines ( Lyman et al, 2019 ).…”

“…Previous studies have also confirmed that heat stress can disrupt ovarian signaling ( Dickson et al, 2018 ), impair estradiol synthesis of granulosa cells ( Li H. et al, 2017 ), and affect ovarian hormone secretion ( Sirotkin, 2010 ). Additionally, heat stress disturbs the ecological communities in the vagina ( An et al, 2021 ), potentially impacting the normal function of the female reproductive tract (FRT). In this study, no significant changes were observed in plasma E 2 and P 4 in the Heat group.…”

“…Previous studies have suggested that acute heat stress could cause intestinal metabolism disorders and microbiota changes in mice ( Wen et al, 2021 ), pigs ( Xiong et al, 2020 ), and poultry ( Zhu et al, 2019 ). Long-term heat stress not only leads to a disorder of the estrous cycle but also alters the vaginal bacterial communities in rats ( An et al, 2021 ).…”

Integrated 16S rDNA Gene Sequencing and Untargeted Metabolomics Analyses to Investigate the Gut Microbial Composition and Plasma Metabolic Phenotype in Calves With Dampness-Heat Diarrhea

“…Recently, a large number of studies have shown that metabolic changes and intestinal microbiota disorders were parallel during the disease progression ( 65 , 66 ). Dysbiosis of the gut microbiota was accompanied with the alteration of plasma metabolome in calves with DHD.…”

Integrative analysis and identification of key elements and pathways regulated by Traditional Chinese Medicine (Yiqi Sanjie formula) in colorectal cancer

“…Sequencing libraries were generated with NEB Next ® Ultra™DNA Library Prep Kit (NEB, United States) following the manufacturer’s instruction. The library was then sequenced on an Illumina NovaSeq 6000 platform, and fragments with 250 bp paired-end reads were generated ( An et al, 2021 ). Fast length adjustment of short (FLASH) reads were applied to merge the paired-end reads from the original DNA fragments, which were assigned to each sample through the unique barcodes.…”