Relationship between salivary antioxidant capacity and phases of the menstrual cycle

Oral microbiome changes associated with the menstrual cycle in healthy young adult females

The relationship between the menstrual cycle and the oral microbiome has not been clarified. The purpose of this study was to assess potential changes in the oral microbiome of healthy young adults using 16S rRNA-based sequencing. Eleven females (aged 23–36 years) with stable menstrual cycles and without any oral problems were recruited. Saliva samples were collected before brushing every morning during the menstrual period. Based on basal body temperatures, menstrual cycles were divided into four phases, namely the menstrual, follicular, early luteal, and late luteal phases. Our results showed that the follicular phase had a significantly higher abundance ratio of the Streptococcus genus than the early and late luteal phases, whereas the abundance ratios of the Prevotella 7 and Prevotella 6 genera were significantly lower in the follicular phase than those in the early and late luteal phases and that in the early luteal phase, respectively. Alpha diversity by the Simpson index was significantly lower in the follicular phase than that in the early luteal phase, and beta diversity showed significant differences among the four phases. Using the relative abundance data and copy numbers of the 16S rRNA genes in the samples, the bacterial amounts in the four phases were compared, and we observed that the follicular phase had significantly lower amounts of the Prevotella 7 and Prevotella 6 genera than the menstrual and early luteal phase, respectively. These results indicate reciprocal changes with the Streptococcus genus and Prevotella genera, particularly in the follicular phase. In the present study, we showed that the oral microbiome profiles are affected by the menstrual cycles of healthy young adult females.

Gonadal steroid hormone secretion during the juvenile period depends on host-specific microbiota and contributes to the development of odor preference

The host microbial community is thought to have an important role in the host endocrine system and behavioral phenotype. We investigated chronological changes of levels of gonadal hormones and corticosterone in the feces of 4- to 8-week-old female germ-free (GF) mice, and conducted odor preference test at 8 weeks of age. We further evaluated the developmental impact of the microbial community by analyzing 4-week-old GF mice orally administered the fecal microbiota of specific pathogen-free (SPF) mice or guinea pigs (GF-SPF mice or GF-Guinea pig mice). The fecal estradiol, progesterone, and corticosterone levels of GF mice were lower than those of SPF mice. Furthermore, the increased levels in GF mice were suggested to be caused by colonization of microbiota of SPF mice or guinea pigs. However, the degree of recovery of progesterone and corticosterone by microbiota of guinea pigs was lower than that by SPF mice. In odor preference tests, interestingly, female GF mice preferred female odors to male odors, although this preference was not seen in other mice. These findings suggested that the microbial community plays an important role in the development of the host endocrine system for gonadal hormones and corticosterone, and odor preference in mice.

Salivary and Urinary Total Antioxidant Capacity as Biomarkers of Oxidative Stress in Humans

Total Antioxidant Capacity (TAC) is a biomarker often used in order to investigate oxidative stress in many pathological conditions. Saliva and urine can be collected noninvasively and represent attractive diagnostic fluids for detecting biomarkers of various pathological conditions. The reviewed case-control and intervention studies that measured salivary or urinary TAC revealed that diseases, antioxidant foods, or supplements and age, gender, and lifestyle factors influenced salivary or urinary TAC. Salivary and urinary TAC were particularly affected by oral or renal status, respectively, as well as by infection; therefore these factors must be taken into account in both case-control and intervention studies. Furthermore, some considerations on sample collection and normalization strategies could be made. In particular, unstimulated saliva could be the better approach to measure salivary TAC, whereas 24 h or spontaneous urine collection should be chosen on the basis of the study outcome and of the creatinine clearance. Finally, the uric acid-independent TAC could be the better approach to evaluate red-ox status of body, in particular after nutritional interventions and in diseases associated with hyperuricaemia.

Salivary markers of oxidative stress in oral diseases

Saliva is an interesting alternative diagnostic body fluid with several specific advantages over blood. These include non-invasive and easy collection and related possibility to do repeated sampling. One of the obstacles that hinders the wider use of saliva for diagnosis and monitoring of systemic diseases is its composition, which is affected by local oral status. However, this issue makes saliva very interesting for clinical biochemistry of oral diseases. Periodontitis, caries, oral precancerosis, and other local oral pathologies are associated with oxidative stress. Several markers of lipid peroxidation, protein oxidation and DNA damage induced by reactive oxygen species can be measured in saliva. Clinical studies have shown an association with oral pathologies at least for some of the established salivary markers of oxidative stress. This association is currently limited to the population level and none of the widely used markers can be applied for individual diagnostics. Oxidative stress seems to be of local oral origin, but it is currently unclear whether it is caused by an overproduction of reactive oxygen species due to inflammation or by the lack of antioxidants. Interventional studies, both, in experimental animals as well as humans indicate that antioxidant treatment could prevent or slow-down the progress of periodontitis. This makes the potential clinical use of salivary markers of oxidative stress even more attractive. This review summarizes basic information on the most commonly used salivary markers of oxidative damage, antioxidant status, and carbonyl stress and the studies analyzing these markers in patients with caries or periodontitis.

Antioxidant capacity of synovial fluid in the temporomandibular joint correlated with radiological morphology of temporomandibular disorders

We investigated the correlation between the antioxidant capacity of synovial fluid and radiological findings of intra-articular structures in patients with disorders of the temporomandibular joint (TMJ). We recruited 21 patients (9 men and 12 women, aged 18-84 years of age) with such disorders, excluding myofascial pain and dysfunction syndrome, or other muscular disorders. The clinical variables recorded included age, sex, interincisal distance, and visual analogue pain scores (VAS). Radiological findings were obtained from diagnostic arthrogram and cone-beam computed tomography (CT). The antioxidant capacity of the synovial fluid was measured by chemiluminescence. Eleven patients were radiologically diagnosed with closed lock, and the remaining 10 with no closed lock. An anchored intra-articular disc was most often seen on cone-beam CT (n=19) followed by perforated disc (n=7), osteoarthrosis (n=7), and anterior disc displacement without reduction (n=5). Although there were no significant differences between antioxidant capacity and age, sex, VAS, or any findings on cone-beam CT, antioxidant capacity was significantly decreased in the patients with closed lock compared with those who did not have closed lock (p=0.02). The results suggest an association between the oxidative stress of the synovial fluid and closed-lock in disorders of the TMJ.