Effects of Caffeine on Bones of Osteoporotic Rats

Nonlinear effects of caffeine on the viability, synthesis and gene expression of chondrocytes from the offspring of rats treated during pregnancy

OBJECTIVE

Evaluate the effects of doses of caffeine administered to pregnant rats on the articular cartilage chondrocytes of their offspring.

METHODS

Twenty-four adult Wistar rats were randomly assigned to four groups, with one control group and three groups being treated with caffeine at doses of 25, 50 and 100 mg/kg throughout pregnancy. At birth, three offspring/females were euthanized so that the chondrocytes could be extracted. At 7, 14 and 21 days of culture, the chondrocytes were subjected to the MTT cell viability assay and an evaluation of their alkaline phosphatase activity and collagen synthesis. Chondrocytes were also stained by Hematoxylin-eosin, PAS, Safranin-O and Alcian Blue. The Sox-9, Runx-2, aggrecan, collagen-II and alkaline phosphatase gene transcript levels were also evaluated. Mean comparisons were performed by the Student-Newman-Keuls test.

RESULTS

Chondrocyte cultures from the 25 mg/kg group had the lowest results, as chondrocytes from this group had reduced viability, percentage of cells, alkaline phosphatase activity and collagen and chondrogenic matrix synthesis. A reduced expression of Sox-9, alkaline phosphatase and collagen-II was also detected in the 25 mg/kg group. Chondrocyte cultures of the group treated with 50 mg/kg caffeine showed reduced collagen synthesis and Sox-9 expression. The caffeine dose of 100 mg/kg also reduced collagen and Sox-9 and alkaline phosphatase expression.

CONCLUSION

Caffeine administered to pregnant rats negatively alters the articular cartilage chondrocytes of their offspring, reducing the synthesis of collagen and Sox-9 expression regardless of the dose. This study also concluded that the effects of caffeine are not linear or dose-dependent.

Inhibition of the osteogenic differentiation of mesenchymal stem cells derived from the offspring of rats treated with caffeine during pregnancy and lactation

Caffeine is an alkaloid that is widely consumed due to its presence in drugs, coffee, tea, and chocolate. This compound passes to offspring through the placenta and milk; can cause teratogenic mutations; and reduces the formation, growth, and mass of bone. Because mesenchymal stem cells (MSCs) are responsible for generating the entire skeleton, we hypothesized that these cells are targets of caffeine. This study evaluated the osteogenic differentiation of MSCs derived from the offspring of rats treated with caffeine during pregnancy and lactation. Twenty-four adult Wistar rats were randomly divided into four groups, including one control group and three experimental groups treated with 25, 50, or 100 mg/kg of caffeine. At weaning, three 21-day-old pups from each dam in each group were euthanized for extraction of bone marrow cells for in vitro tests. Caffeine doses of 50 and 100 mg/kg significantly reduced the activity of alkaline phosphatase at 7, 14, and 21 days and the expression of collagen I at 21 days. However, the expression of gene transcripts for alkaline phosphatase, Runx-2, and bone sialoprotein, as well as the synthesis of mineralization nodules, decreased significantly in all groups treated with caffeine. The expression of osteocalcin was significantly reduced only in the group treated with 50 mg/kg caffeine. The caffeine that passes from the mother to the offspring during pregnancy and lactation reduces the osteogenic differentiation of MSCs. We propose that this reduction in the osteogenic potential of MSCs may be involved in the pathogenesis of osteopenia resulting from caffeine consumption.

Effects of Coffee Intake and Intraperitoneal Caffeine on Bone Repair Process - A Histologic and Histometric Study

Studies have suggested that caffeine acts on bone promoting an increase of calcium excretion, inhibition of osteoblast proliferation and delay in tissue repair process, raising the risk of fractures, osteoporosis, periodontal disease and affecting the success of bone reconstructive procedures. The aim of this study was to analyze histomorphometrically the process of alveolar bone healing after tooth extraction in rats subjected to daily intake of boiled coffee or intraperitoneal administration of caffeine. Forty-five male rats were divided according to the treatment in Control group (C); Coffee group (CO) - treated with coffee since birth; and Caffeine (CAF) - intraperitoneal injection of aqueous solution of caffeine 1.5% (0.2 mL/100g body weight) for 30 days. When weighing between 250-300 g they were anesthetized, subjected to extraction of the maxillary right incisor, and euthanized 7, 21 and 42 days after surgery for histological assessments of bone volume and the quality of formed bone in the dental socket. The qualitative results demonstrated larger amounts of blood clot and immature bone in animals under treatment of pure caffeine compared to coffee and control. Histometric analysis revealed that coffee treatment led to a 40% drop in bone formation, and caffeine a 60% drop in comparison to control animals (ANOVA p≤0.01). It was concluded that both the daily ingestion of coffee and the intraperitoneal administration of caffeine in rats delayed the alveolar bone reparative process after tooth extraction, and this effect was more aggressive when pure caffeine was used.