Alzheimer’s disease (AD) is the most common type of dementia leading to progressive memory loss and cognitive impairment. Considering that pharmacological treatment options for AD are few and not satisfactory, increasing attention is being paid to dietary components that may affect the development of the disease. Such a dietary component may be caffeine contained in coffee, tea or energy drinks. Although epidemiological data suggest that caffeine intake may counteract the development of cognitive impairment, results of those studies are not conclusive. The aim of the present study is to review the existing experimental studies on the efficacy of caffeine against AD and AD-related cognitive impairment, focusing on the proposed protective mechanisms of action. In conclusion, the reports of studies on experimental AD models generally supported the notion that caffeine may exert some beneficial effects in AD. However, further studies are necessary to elucidate the role of caffeine in the effects of its sources on cognition and possibly AD risk.

It is believed that apple fruits contain components with health-promoting effects, including some antidiabetic activity. One of the most known apple compounds is phloridzin, a glucoside of phloretin. Phloridzin and phloretin were reported to exert some favorable skeletal effects in estrogen-deficient rats and mice. The aim of the study was to investigate the effects of phloridzin on musculoskeletal system in rats with type 2 diabetes induced by a high-fat diet (HFD) and streptozotocin (STZ). The experiments were performed on mature female Wistar rats, divided into control rats (fed a standard laboratory diet), HFD/STZ control rats, and HFD/STZ rats receiving phloridzin (20 or 50 mg/kg/day per os) for four weeks. Serum biochemical parameters, muscle mass and strength, bone mass, density, histomorphometric parameters and mechanical properties were determined. The HFD/STZ rats developed hyperglycemia, with decreases in the muscle mass and strength and profound osteoporotic changes. Phloridzin at 20 mg/kg markedly augmented the unfavorable effects of diabetes on the muscle mass and strength and decreased growth of bones, whereas, at 50 mg/kg, it did not affect most of the investigated musculoskeletal parameters. Results of the study indicate the possibility of unfavorable effects of phloridzin on the musculoskeletal system in conditions of hyperglycemia.

There is a great interest in substances of plant origin, which may exert health-promoting activities in diabetes and its complications. Previous studies suggested that diosgenin may favorably affect both glucose metabolism and osteoporosis. The aim of the study was to investigate the effects of diosgenin on the skeletal disorders induced by experimental type 1 diabetes (T1D) in rats. The experiments were performed on 3-month-old female rats, divided into three groups: I - healthy control rats, II - streptozotocin-induced diabetic control rats, III - diabetic rats receiving diosgenin. T1D was induced by a single streptozotocin injection (60 mg/kg i.p.). Diosgenin administration (50 mg/kg/day p.o.) started two weeks later and lasted four weeks. Serum bone turnover markers and other biochemical parameters, bone mass and mineralization, mechanical properties and histomorphometric parameters were examined. Diabetes induced profound metabolic disturbances and disorders of cancellous bone microarchitecture and strength. Diosgenin did not favorably affect the serum bone turnover markers and other biochemical parameters, bone mass, mineralization and mechanical properties in the diabetic rats. However, it counteracted the effect of diabetes on the growth plate and cancellous bone microarchitecture in the distal femur, indicating some limited beneficial influence on the skeleton.

In diabetes hyperglycemia, excessive production of free radicals and present oxidative stress lead to many complications in the body, including male reproductive system disorders. To prevent the development of diabetic complications in the testes resulting from them, it seems beneficial to include compounds considered as natural antioxidants. Honokiol and magnolol are neolignans obtained from magnolia bark, which possess proven antioxidant properties. The aim of this study was to evaluate the effect of honokiol and magnolol on the parameters of oxidative stress, polyol pathway and glycation products in the testes as well as on selected biochemical parameters in the blood serum of rats with type 2 diabetes. The study was conducted on mature male Wistar rats with high fat diet and streptozotocin-induced type 2 diabetes. Neolignans-treated rats received honokiol or magnolol orally at the doses of 5 or 25 mg/kg, respectively, for 4 weeks. Parameters related to glucose and lipid homeostasis, basic serological parameters and sex hormones level in the serum as well as polyol pathway parameters, antioxidant enzyme activity, endogenous antioxidants level, sumaric parameters for oxidative stress and oxidative damage in the testes were estimated. Oral administration of honokiol and magnolol turned out to be beneficial in combating the effects of oxidative stess in the testes, but showed no favorable effects on serum biochemical parameters. Additionally, magnolol compared to honokiol revealed more advantageous impact indicating the reversal of the effects of diabetic complications in the male reproductive system and counteracted oxidative stress damages and polyol pathway disorders in the testes.

Although postmenopausal osteoporosis often occurs concurrently with diabetes, little is known about interactions between estrogen deficiency and hyperglycemia in the skeletal system. In the present study, the effects of estrogen deficiency on the development of biochemical, microstructural, and mechanical changes induced by streptozotocin-induced diabetes mellitus (DM) in the rat skeletal system were investigated. The experiments were carried out on nonovariectomized (NOVX) and ovariectomized (OVX) control and diabetic mature female Wistar rats. Serum levels of bone turnover markers (CTX-I and osteocalcin) and 23 cytokines, bone mass and mineralization, histomorphometric parameters, and mechanical properties of cancellous and compact bone were determined. The results were subjected to two-way ANOVA and principal component analysis (PCA). Estrogen deficiency induced osteoporotic changes, with increased bone resorption and formation, and worsening of microstructure (femoral metaphyseal BV/TV decreased by 13.0%) and mechanical properties of cancellous bone (the maximum load in the proximal tibial metaphysis decreased by 34.2%). DM in both the NOVX and OVX rats decreased bone mass, increased bone resorption and decreased bone formation, and worsened cancellous bone microarchitecture (for example, the femoral metaphyseal BV/TV decreased by 17.3% and 18.1%, respectively, in relation to the NOVX controls) and strength (the maximum load in the proximal tibial metaphysis decreased by 35.4% and 48.1%, respectively, in relation to the NOVX controls). Only in the diabetic rats, profound increases in some cytokine levels were noted. In conclusion, the changes induced by DM in female rats were only slightly intensified by estrogen deficiency. Despite similar effects on bone microstructure and strength, the influence of DM on the skeletal system was based on more profound systemic homeostasis changes than those induced by estrogen deficiency.

The gut microbiota plays an important role in maintaining homeostasis, including that of the skeletal system. Antibiotics may affect the skeletal system directly or indirectly by influencing the microbiota. Probiotic bacteria have been reported to favorably affect bones in conditions of estrogen deficiency. The aim of this study was to investigate the effects of azithromycin (AZM) administered alone or with probiotic bacteria (Lactobacillus rhamnosus; LR) on bones in estrogen-deficient rats. The experiments were carried out on mature rats divided into five groups: non-ovariectomized (NOVX) control rats, ovariectomized (OVX) control rats, and OVX rats treated with: LR, AZM, or AZM with LR. The drugs were administered for 4 weeks. Serum biochemical parameters, bone mineralization, histomorphometric parameters, and mechanical properties were examined. Estrogen deficiency increased bone turnover and worsened cancellous bone microarchitecture and mechanical properties. The administration of LR or AZM slightly favorably affected some skeletal parameters of estrogen-deficient rats. The administration of AZM with LR did not lead to the addition of the effects observed for the separate treatments, indicating that the effects could be microbiota-mediated.