The microarchitecture and chemical composition of the femur neck of senescent female rats after different physical training protocols.

A sedentary lifestyle, coupled with a decrease in estrogen, impairs bone homeostasis, favoring to the development of osteopenia and osteoporosis, both recognized as risk factors for fractures. Here, we investigated the quality of the femur, particularly the femur neck region, and the ambulation performance of senescent rats subjected to three different physical training protocols during the periestropause period. Forty-eight female rats, 18 months of age, were subjected to a 120-day training period, three times a week. The rats were distributed into four groups: aerobic training (AT), strength training (ST), concurrent training (CT), or no training (NT). After the experimental period, at 21 months of age, ambulation performance and femur were analyzed using microtomography, Raman stereology, densitometry, and mechanical strength tests. The results demonstrated greater remodeling activity and improvement in resistance and bone microarchitecture in the femur neck of senescent female rats after undergoing physical training. Our verified higher intensities of bands related to collagen, phosphate, amide III, and amide I. Furthermore, the analysis of the secondary collagen structures indicated alterations in the collagen network due to the exercise, resulting in increased bone strength. Both AT and strength-based training proved beneficial, with AT showing greater adaptations in bone density and stiffness in the femur, while strength-based training greater adaptations in trabecular and cortical structure. These insights contribute to the understanding of the potential interventions for preventing osteopenia and osteoporosis, which are critical risk factors for fractures.

Analysis of the femoral neck from rats in the periestropause treated with oxytocin and submitted to strength training.

Among the interventions used to prevent osteoporosis in female organisms, strength training (ST) and oxytocin (OT) stand out, as a promising hormone with anabolic action on bone. This study aimed to verify whether the combined action of OT and ST, compared to isolated interventions, potentiates the bone remodeling process of the femoral neck of Wistar rats during periestropause. Forty Wistar rats (18 months) with irregular estrous cycle were randomly distributed into groups: 1-Vehicle (Veh; NaCl 0.15 mol/L ip); 2-Oxytocin (Ot; 134 µg/kg/ip); 3-Strength training (St); 4-Ot + St. The animals of the 1, 2 and 4 groups received two intraperitoneal injections with an interval of 12 h every 30 days, totaling 8 injections at the end of the experimental period (18 to 21 months). The animals in the St and Ot + St groups performed ST on a ladder 3 times a week, maximal voluntary carrying capacity (MVCC) test monthly. After 120 days, the animals were euthanized; the femur was collected for analysis of biomechanical testing, densitometry, bone microtomography, Raman spectroscopy, tissue PCR, and blood for analysis of bone biomarkers, liver damage, and oxidative stress. The main effects in the Ot group were observed in the maximum load and energy in the compression testing (femoral head), and stiffness and energy in the three-points bending testing (femur diaphysis). In addition, the main effects occurred on the bone mineral density (BMD), cortical thickness (Ct.Th), number of pores (Po.N), polar moment of inertia (J), trabecular thickness (Tb.Th), and connectivity density (Conn.Dn), Bone alkaline phosphatase (Alp), Tumor necrosis factor receptor superfamily member 11b (Opg), Tumor necrosis factor ligand superfamily member 11 (Rankl) and Cathepsin K (Ctsk) expression. There was an effect in the tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP). In the St group, the main effect was observed on the energy (compression and the three-points bending), stiffness, aBMD, BMD, cortical bone area (Ct.Ar), Po.N, trabecular bone volume (BV/TV), Tb.Th and in the mineralization ratio (ѵ1PO4/proline), Runt-related transcription factor 2 (Runx2), Bone morphogenetic protein 2 (Bmp2), Alp, Osteopontin/secreted phosphoprotein 1 (Opn/Spp1), Opg, Tumor necrosis factor receptor superfamily member 11ª (Rank), Rankl, Ctsk expression. There was an effect in the TRAP and ALP. The interaction in the combination of therapies in the Ot + St group was verified in energy to maximum load (compression and three-points bending testing), stiffness, BMD, Ct.Th, J, Tb.Th and ѵ1PO4/proline. In the gene analysis there was interaction in the Runx2, Osterix/Sp7 transcription factor (Osx/Sp7), Bmp2, Alp, Osteocalcin/Bone gamma-carboxyglutamate protein (Ocn/Bglap), Opg, Rankl and Acid phosphatase 5, tartrate resistant (Trap/Acp5) expression. In addition, the combination of OT and ST resulted in a higher maximum load compared to the Veh group, with higher BV/TV than the Ot group, higher Rankl and Ctsk expression than Veh and Ot groups, and lower Po.N and lower activity of TRAP than the other groups. In oxidative stress, total antioxidant capacity (TAC) was lower. These results showed that the combination of interventions is a promising anabolic strategy for the prevention of osteoporosis in the period of periestropause, standing out from the effects of isolated interventions.

The action of oxytocin on the bone of senescent female rats.

AIMS: This study verified the action of oxytocin (OT) as a preventive measure to control bone damage during aging in female rats. MAIN METHODS: Wistar rats received saline (0.15 mol/L/IP; Vehicle Group), Atosiban/AT (300 µg/Kg/IP; At Group), OT (134 µg/Kg/IP; Ot Group), or AT+OT (OT injections 5 min after AT; At+Ot Group), at 19 and 20 months of age. A functional test was performed immediately before and 30 days after the injections to analyze the animals' gait. KEY FINDINGS: Animals in the At group had higher alkaline phosphatase (ALP) activity, lower cortical and trabecular thickness, fewer trabeculae, higher expression of tartrate-resistant acid phosphatase (TRAP) and lower osteocalcin (OCN), higher cortical porosity, and lower moment of inertia and bone strength at the femoral neck. OT administration increased lipidic peroxidation and plasma superoxide dismutase (SOD), and provided, in the femoral neck, lower expression of TRAP and higher OCN, greater cortical and trabecular thickness, a greater number of trabeculae, bone mineral density (BMD), higher inertia bone strength, and lower cortical porosity. At + Ot group showed great similarity with the vehicle group, higher SOD, and BMD. An increase in stride length and no increase in base width of 21-month-old animals were observed after OT, unlike animal's vehicle or AT. SIGNIFICANCE: Endogenous OT plays an important role in the regulation of bone remodeling during periestropause, and exogenous OT stands out as a potential preventive intervention in this period to improve bone quality with functional repercussions, possibly providing better gait activity.

Effects of orchiectomy and testosterone replacement therapy on redox balance and salivary gland function in Wistar rats.

The objective of this study was to investigate the effects of orchiectomy (ORX) and testosterone replacement therapy (TRT) on redox balance and function of salivary glands. Forty-five young adult male Wistar rats (3 months old) were either castrated bilaterally or underwent fictitious surgery (SHAM) and were subsequently distributed into 3 groups: SHAM, ORX, and TRT (castrated rats that received an intramuscular injection of testosterone cypionate 10 mg/kg/weekly). All treatments started 4 weeks after castration (4 months old) and lasted 4 weeks (5 months old). At the end of treatment, pilocarpine-induced salivary secretion was collected to analyze salivary flow rate and biochemistry composition, and the parotid (PG) and submandibular (SMG) glands were sampled for redox balance markers and histomorphometric analyses. ORX increased salivary flow rate, calcium, phosphate, and chloride, and decreased total protein and amylase, while not changing the salivary buffer capacity, pH, sodium, and potassium compared to SHAM. TRT restored all salivary parameters to SHAM values. ORX increased oxidative lipid and protein damage, total antioxidant capacity, and uric acid in both salivary glands compared to SHAM. Superoxide dismutase, catalase, and glutathione peroxidase activities were greater only in the SMG of the ORX group in relation to SHAM. ORX decreased duct and acini area, while increasing connective tissue in the PG. On the other hand, ORX reduced duct area and increased acini area in the SMG compared to SHAM. TRT restored the redox balance and histomorphometric parameters to close to SHAM values in both salivary glands. Orchiectomy-induced salivary gland dysfunction was characterized by an increase in the salivary flow rate and changes in the secretion of total protein, amylase, and electrolytes, which are key factors, considered important for maintaining oral health status. To sum up, orchiectomy impaired the redox balance of the salivary glands. Our results also showed that TRT reversed the oxidative damage, morphological alterations, and salivary gland dysfunction induced by orchiectomy. Therefore, these results suggest an important action of testosterone on the redox balance and secretory ability of salivary glands.

A influência da ocitocina e do antagonista do receptor de ocitocina no metabolismo ósseo, estresse oxidativo, padrões da marcha e análise do tipo ansioso de ratas senescentes / The influence of oxytocin and the oxytocin receptor antagonist on bone metabolism, oxidative stress, gait and analysis of the anxious type of senescent rats

O objetivo deste estudo foi avaliar a ação da ocitocina (OT) endógena, bem como o efeito potencializador da OT exógena sobre o metabolismo ósseo, estresse oxidativo, marcha e análise do tipo ansioso de ratas na periestropausa. Ao completar 19 meses, os animais receberam injeções de solução salina (0,15M/ip), Atosiban (AT) (At; 300 µg/Kg/ip), OT (Ot; 134 µg/Kg/ip) ou At+Ot (injeções de OT 5 minutos após AT), sendo duas injeções de cada substância por dia, com intervalos de 12 horas entre elas, a cada 30 dias até a idade de 21 meses. Após trinta dias sem tratamentos, foi realizada a coleta de amostras biológicas. Aspartato aminotransferase (AST), marcador de dano hepático, foi menor em Ot e At+Ot. Substância ácida reativa ao ácido tiobarbitúrico (TBARs É¥mol/L), marcador do dano oxidativo lipídico, foi maior no grupo Ot comparado ao At (p = 0,0093), e menor no At+Ot em relação ao Ot (p = 0,0040). Houve maior defesa antioxidante enzimática avaliada por meio da superóxido dismutase (SOD) no grupo Ot em comparação ao Veh (p < 0,0312). Por sua vez, no grupo At houve maior atividade enzimática da fosfatase alcalina (FAL) em relação ao Veh e Ot (p < 0,0001; At+Ot: p = 0,0015). A espessura do tecido ósseo compacto foi menor no grupo At em relação ao Veh (p = 0,0228), no entanto, foi maior no grupo Ot em relação ao Veh e At (p = 0,0132, p < 0,0001); no grupo At+Ot foi menor quando comparado ao grupo Ot (p = 0,0003). O número de trabéculas ósseas foi menor no grupo At comparado ao Veh (p = 0,0240), e maior em Ot em relação ao At (p = 0,0084). Quanto a análise imunoistoquímica realizada no osso cortical do colo do fêmur, o grupo Ot apresentou maior expressão de osteocalcina (OCN) em comparação aos grupos Veh e At (p = 0,05 e 0,0033), e menor expressão no grupo At+Ot em relação ao grupo Ot (p = 0,05). A expressão de fosfatase ácida resistente ao tartarato (TRAP) foi menor no grupo Ot comparado aos grupos Veh e At (p = 0,05 e 0,0033), contudo foi maior no grupo At+Ot comparado ao Ot (p = 0,05). A densidade mineral óssea areal (DMO) foi significativamente maior nos grupos Ot e At+Ot em relação à Veh (p < 0,0001) e grupo At (p = 0,0231, p = 0,0418). Por sua vez, a relação mineral-matriz (vPO4/Proline) foi maior e a substituição de carbonato tipo B (CO3/vPO4) foi menor no grupo Veh. O teste de deambulação por comprimento (cm) usado para avaliar função musculoesquelética, aumentou em última análise no grupo Ot em relação ao grupo Veh - F (p = 0,0078), At - F (p = 0,0023), bem como aumentou sobre Ot - I (p = 0,0094). O teste do labirinto, usado para estudar o comportamento chamado "tipo ansioso", demonstrou que a OT inverte a redução nas entradas dos braços fechados, reduz o tempo gasto no centro causado pelo At. Os resultados obtidos neste estudo demonstram que a OT ajuda a modular o ciclo de remodelação óssea de ratas senescentes, melhorando os parâmetros de densitometria óssea e os parâmetros funcionais musculoesquelético(AU)

The objective of this study was to evaluate the endogenous oxytocin (OT) action, as well as the potentiating effect of exogenous OT on the bone metabolism, oxidative stress, gait and analysis of the anxious type of rats in periestropause. Upon completing 19 months, the animals received injections of saline solution (0.15M/ip), Atosiban (AT) (At; 300 µg/Kg/ip), OT (Ot; 134 µg/Kg/ip) or At+Ot (OT injections 5 minutes after AT), being two injections of each substance per day, with intervals of 12 hours between them, every 30 days until the age of 21 months. After thirty days without treatment, biological samples were collected. Aspartate aminotransferase (AST), a marker of liver damage, was lower after Ot and At+Ot. Acid reactive substance to thiobarbituric acid (TBARs µmol/L), marker of lipid oxidative damage, was higher in the Ot group compared to At (p = 0.0093), and lower in At+Ot compared to Ot (p = 0.0040). There was a higher antioxidant enzymatic defense evaluated by means of superoxide dismutase (SOD) in the Ot group compared to Veh (p < 0.0312). In turn, in the At group there was greater alkaline phosphatase (FAL) enzymatic activity in relation to Veh and Ot (p < 0.0001; At+Ot: p = 0.0015). The thickness of the compact bone tissue was smaller in the At group in relation to Veh (p = 0.0228), however, it was greater in the Ot group in relation to Veh and At (p = 0.0132, p < 0.0001); in the At+Ot group it was smaller when compared to Ot (p = 0.0003). The number of bone trabecules was smaller in the At group compared to the Veh (p = 0.0240), and greater in Ot in relation to the At (p = 0.0084). As for the immunohistochemical analysis performed on the cortical bone of the femoral neck, the Ot group presented a higher expression of osteocalcin (OCN) compared to the Veh and At groups (p = 0.05 and 0.0033), and lower expression in the At+Ot group compared to the Ot group (p = 0.05). The tartrate-resistant acid phosphatase (TRAP) expression was lower in the Ot group compared to the Veh and At groups (p = 0.05 and 0.0033), however it was higher in the At+Ot group compared to Ot (p = 0.05). The sandal mineral density (BMD) was significantly higher in the Ot and At+Ot groups compared to Veh (p < 0.0001) and At group (p = 0.0231, p = 0.0418). In turn, the parent mineral ratio (vPO4/Proline) was higher and the replacement of carbonate type B (CO3/vPO4) was lower in the Veh group. The walking test per length (cm) used to evaluate musculoskeletal function was ultimately increased in group Ot in relation to group Veh - F (p = 0.0078), At - F (p = 0.0023), as well as increased over Ot - I (p = 0.0094). The labyrinth test, used to study the so-called "anxious type" behavior, demonstrated that the OT reverses the reduction in the entries of the closed arms, reducing the time spent in the center caused by At. The results obtained in this study show that the OT helps to modulate the cycle of bone remodeling of senescent rats, improving the parameters of bone densitometry and the musculoskeletal functional parameters(AU)