Effects of oligonol on the submandibular gland in ovariectomized rats

Bone marrow derived mesenchymal stem cells restored GLUT1 expression in the submandibular salivary glands of ovariectomized rats

OBJECTIVE

Loss of ovarian function in menopause is commonly associated with salivary gland dysfunction. The aim is to study the possible therapeutic effect of bone marrow mesenchymal stem cells (BM-MSCs) on the altered structure of the submandibular salivary glands (SMGs) of ovariectomized rats.

DESIGN

Twenty-four female, adult, Wistar rats were used and distributed into three groups (8 rats/group). The control group included sham-operated rats. The ovariectomized group consisted of rats with removed ovaries. The third group consisted of ovariectomized rats received injections, via tail, of MSCs extracted from bone marrow of 3-weeks-old rat hind limb (BM-MSC group). Four weeks after BM-MSC transplantation, the bone mineral density (BMD) of the femur was detected. The SMG was dissected and processed for histological, immunohistochemical, and histomorphometric analyses.

RESULTS

The ovariectomized rats depicted low BMD in the femur. The SMG acini revealed atrophy. The ductal and acinar cells depicted vacuolization and abnormal nuclear histology. GLUT1 immunostaining was decreased in SMG ducts. The BM-MSC group resumed the normal SMG histology and GLUT1 immunolabelling.

CONCLUSIONS

BM-MSC therapy restored the normal SMG structure and GLUT1 immunostaining in the treated ovariectomized rats, suggesting improved glucose transporting function.

SIRT1 signaling pathways in sarcopenia: Novel mechanisms and potential therapeutic targets

Sarcopenia is an aging-related skeletal disease characterized by decreased muscle mass, strength, and physical function, severely affecting the quality of life (QoL) of the elderly population. Sirtuin 1 (SIRT1), as a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylases, has been reported to participate in various aging-related signaling pathways and exert protective effect on many human diseases. SIRT1 functioned as an important role in the occurrence and progression of sarcopenia through regulating key pathways related to protein homeostasis, apoptosis, mitochondrial dysfunction, insulin resistance and autophagy in skeletal muscle, including SIRT1/Forkhead Box O (FoxO), AMP-activated protein kinase (AMPK)/SIRT1/nuclear factor κB (NF-κB), SIRT1/p53, AMPK/SIRT1/peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), and SIRT1/live kinase B1 (LKB1)/AMPK pathways. However, the specific mechanisms of these processes have not been fully illuminated. Currently, several SIRT1-mediated interventions on sarcopenia have been preliminarily developed, such as SIRT1 activator polyphenolic compounds, exercising and calorie restriction. In this review, we summarized the predominant mechanisms of SIRT1 involved in sarcopenia and therapeutic modalities targeting the SIRT1 signaling pathways for the prevention and prognosis of sarcopenia.

Effect of deferoxamine and ferrostatin-1 on salivary gland dysfunction in ovariectomized rats

The mechanism underlying xerostomia after menopause has not yet been fully elucidated. This study aimed to investigate the mechanism of xerostomia and the effect of the ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (FER) on salivary gland dysfunction in a postmenopausal animal model. Twenty-four female Sprague-Dawley rats were randomly divided into four groups: a SHAM group (n = 6, sham-operated rats), an OVX group (n = 6, ovariectomized rats), an FER group (n = 6, ovariectomized rats injected intraperitoneally with FER), and a DFO group (n = 6, ovariectomized rats injected intraperitoneally with DFO). GPX4 activity, iron accumulation, lipid peroxidation, inflammation, fibrosis, and salivary gland function were analyzed. Recovery of GPX4 activity and a decrease in iron accumulation and cytosolic MDA + HAE were observed in the DFO group. In addition, collagen I, collagen III, TGF-β, IL-6, TNF-α, and TGF-β levels were decreased in the DFO group compared to the OVX group. Recovery of GPX4 activity and the morphology of mitochondria, and reduction of cytosolic MDA + HAE were also observed in the FER group. In addition, decreased expression of inflammatory cytokines and fibrosis markers and increased expression of AQP5 were observed in both the DFO and FER groups. Postmenopausal salivary gland dysfunction is associated with ferroptosis, and DFO and FER may reverse the postmenopausal salivary gland dysfunction after menopause. DFO and FER are hence considered promising treatments for postmenopausal xerostomia.

Effect of Echinochrome A on Submandibular Gland Dysfunction in Ovariectomized Rats

Post-menopausal dry mouth or xerostomia is caused by reduced salivary secretion. This study aimed to investigate the efficacy of echinochrome A (Ech A) in alleviating submandibular gland dysfunctions in ovariectomized rats that mimic menopause. Female rats that were eight-weeks-old were randomly divided into SHAM-6, -12; OVX-6, -12; and ECH-6, -12 groups (consisting of 6- and 12-weeks post-sham-operated, ovariectomized, and Ech A-treated ovariectomized rats, respectively). The ECH groups had lower body weight than OVX but similar food intake and estradiol or estrogen receptor β expression. However, the ECH groups had lower mRNA expression of sterol-regulatory element binding protein-1c (Srebp-1c), acetyl-CoA carboxylase (Acc), fatty acid synthase (Fasn), cluster of differentiation 36 (Cd36), and lipid vacuole deposition than OVX mice. Moreover, reactive oxygen species (ROS), malondialdehyde (MDA), and iron accumulation were lower in the ECH than in the OVX groups. Fibrosis markers, transforming growth factor β (Tgf-βI and Tgf-βII mRNA) increased in the OVX than SHAM groups but decreased in the ECH groups. Aquaporin (Aqp-1 and Aqp-5 mRNA) and mucin expressions were downregulated in the OVX groups but improved with Ech A. In addition, Ech A prevented post-menopausal salivary gland dysfunction by inhibiting lipogenesis and ferroptosis. These findings suggest Ech A as an effective remedy for treating menopausal dry mouth.

Resveratrol alleviates salivary gland dysfunction induced by ovariectomy in rats

Resveratrol (Res), found abundant in many medicinal plants, exerts multiple biological functions in the body, including anti-inflammatory, antioxidant, and anti-aging properties. Xerostomia is a major symptom of salivary gland dysfunction in menopausal women, which significantly compromises the quality of life. Here, we investigated the effect of Res on estrogen deficiency-induced salivary gland dysfunction in rats. We found that Res administration could reduce body weight and water consumption, and increase salivary fluid secretion and blood flow of the submandibular gland. Furthermore, Res therapy alleviated histological lesions, increased AQP5 expression, and inhibited cell apoptosis in submandibular gland tissue. Meanwhile, the action of antioxidants was restored and the levels of inflammatory cytokines were attenuated by Res supplementation. Collectively, Res effectively improved estrogen deficiency-induced hyposalivation, which may provide a novel, safe, and practical approach to protect the salivary glands of estrogen-deficient females against xerostomia.

Effect of oligonol, a lychee-derived polyphenol, on skeletal muscle in ovariectomized rats by regulating body composition, protein turnover, and mitochondrial quality signaling

Oligonol is a low‐molecular‐weight polyphenol product derived from lychee (Litchi chinensis Sonn.) fruits. This study was focused on the effects of oligonol on the skeletal muscle of ovariectomized rats. We randomly divided female Sprague–Dawley rats into three groups: a sham surgery control group (Sham), an ovariectomy (OVX) group, and an OVX group treated with oligonol (OVX + Oligonol). Oligonol was intraperitoneally administrated at 30 mg/kg daily for 6 weeks. Oligonol treatment after OVX decreased body weight and fat mass, regulated lipid metabolism in skeletal muscle, without loss of lean mass and bone. Bone turnover was not affected by oligonol. In protein synthesis and degradation, oligonol increased the levels of the mammalian target of rapamycin and its downstream targets, eukaryotic initiation factor 4E‐binding protein 1 and 70‐kDa ribosomal protein S6 kinase, and it stimulated the expression of ubiquitin‐proteasome pathway proteins, the forkhead box transcription factors of the class O and the muscle ring‐finger protein‐1. Moreover, oligonol treatment enhanced mitochondrial biogenesis and dynamics. Thus, our results indicated that oligonol treatment had beneficial effects on the skeletal muscle in an estrogen‐deficiency rat model.