Differential responses of bone to angiotensin II and angiotensin(1-7): beneficial effects of ANG(1-7) on bone with exposure to high glucose.

Osteoporosis, diabetes, and hypertension are common concurrent chronic disorders. This study aimed to explore the respective effects of angiotensin II (ANG II) and angiotensin(1-7) [ANG(1-7)], active peptides in the renin-angiotensin system, on osteoblasts and osteoclasts under high-glucose level, as well as to investigate the osteo-preservative effects of ANG II type 1 receptor (AT1R) blocker and ANG(1-7) in diabetic spontaneously hypertensive rats (SHR). ANG II and ANG(1-7), respectively, decreased and increased the formation of calcified nodules and alkaline phosphatase activity in MC3T3-E1 cells under high-glucose level, and respectively stimulated and inhibited the number of matured osteoclasts and pit resorptive area in RANKL-induced bone marrow macrophages. Olmesartan and Mas receptor antagonist A779 could abolish those effects. ANG II and ANG(1-7), respectively, downregulated and upregulated the expressions of osteogenesis factors in MC3T3-E1 cells. ANG II promoted the expressions of cathepsin K and MMP9 in RAW 264.7 cells, whereas ANG(1-7) repressed these osteoclastogenesis factors. ANG II rapidly increased the phosphorylation of Akt and p38 in RAW 264.7 cells, whereas ANG(1-7) markedly reduced the phosphorylation of p38 and ERK under high-glucose condition. After treatments of diabetic SHR with valsartan and ANG(1-7), a significant increase in trabecular bone area, bone mineral density, and mechanical strength was only found in the ANG(1-7)-treated group. Treatment with ANG(1-7) significantly suppressed the increase in renin expression and ANG II content in the bone of SHR. Taken together, ANG II/AT1R and ANG(1-7)/Mas distinctly regulated the differentiation and functions of osteoblasts and osteoclasts upon exposure to high-glucose condition. ANG(1-7) could protect SHR from diabetes-induced osteoporosis.

Muscone Ameliorates LPS-Induced Depressive-Like Behaviors and Inhibits Neuroinflammation in Prefrontal Cortex of Mice.

Depression is partially caused by inflammation in the central nervous system. Early study demonstrated that musk, glandular secretion from male musk deer, exerted an antidepressant-like effect. The aim of this study was to investigate if muscone, a bioactive ingredient in musk, could ameliorate neuroinflammation and depressive-like behaviors as well as explore the potential action mechanism. Mice were intraperitoneally (i.p.) injected with muscone for 2 weeks prior to administration of lipopolysaccharides (LPS, 1mg/kg, i.p.). Pre-treatment with muscone reversed the LPS-induced decrease in body weight within 24h and ameliorated depressive-like behaviors shown by sucrose preference, tail suspension test, and forced swimming test. LPS-induced activation of microglial cells and elevation in expression of inflammatory cytokines including IL-1ß, RANTES, and MCP-1 in the prefrontal cortex of mice were effectively abrogated by muscone, which significantly down-regulated expression of TLR4, MyD88, Caspase-1, NLRP3, renin, and Ang II. In addition, treatment of BV2 microglia cells with muscone markedly attenuated the LPS-induced rise in protein expression of TLR4, Ang II, and IL-1ß. This study revealed that muscone could ameliorate LPS-induced depressive-like behaviors by repressing neuroinflammation in the prefrontal cortex of mice caused by its suppression on microglia activation and production of inflammatory cytokines via acting on TLR4 pathway and RAS cascade.

Paricalcitol alleviates lipopolysaccharide-induced depressive-like behavior by suppressing hypothalamic microglia activation and neuroinflammation.

Depression is highly prevalent in patients suffering from chronic inflammatory diseases. Dysregulated neuroinflammation and concomitant activated microglia play a pivotal role in the pathogenesis of depression. Paricalcitol (Pari), a vitamin D2 analogue, has been demonstrated to exert anti-inflammative effects on renal and cardiovascular diseases. In this study, mice were pretreated with Pari before being induced to acute depression-like behaviors by systemic lipopolysaccharide (LPS) injection. To determine the therapeutic effects of Pari, alterations in acute body weight, sucrose preference, forced swimming and tail suspension tests were assessed. Then, alterations of pro-inflammation cytokine IL1-ß level and microglia activity in the hypothalamus, which are involved in the pathophysiology of depression, were examined. The results showed that Pari significantly alleviated systemic LPS injection induced depressive-like behaviors as shown by increased sucrose preference and decreased TST and FST immobility. Pari could specifically regulate microglia-mediated neuroinflammation process and local activity of renin-angiotensin system to exert its anti-depressant effects. This study demonstrated a potential for paricalcitol in treating depressive symptoms induced by systemic inflammation, particularly in patients with chronic hypertension.

Effect of the water fraction isolated from Fructus Ligustri Lucidi extract on bone metabolism via antagonizing a calcium-sensing receptor in experimental type 1 diabetic rats.

Our previous studies have demonstrated that the extract of Fructus Ligustri Lucidi (FLL) can maintain in vivo calcium homeostasis in aged and ovariectomized rats. This study was designed to elucidate the action of water fraction isolated from the FLL extract on bone metabolism and a calcium-sensing receptor (CaSR) in parathyroid glands and kidneys of diabetic rats. The streptozotocin-induced diabetic rats were treated with vehicle, FLL extract, and the water fraction (WF) isolated from the FLL extract for 4 weeks. Treatment with WF dramatically increased the serum levels of both calcium and parathyroid hormone and reduced urinary calcium excretion in diabetic rats as well as improved the pathological changes of trabecular bone as shown by the increased BA/TA, BMD/BV, and BV/TV. The mRNA expression of the calcium-binding protein 9k and protein expression of a vitamin D receptor (VDR) and plasma membrane Ca-ATPase in duodenum were significantly increased in diabetic rats after treatment with WF, which reduced the expression of CaSR in parathyroid gland and kidney as well as inhibited the up-regulation of VDR and 25-hydroxyvitamin D-24 hydroxylase expressions in the kidney of diabetic rats. This study reveals that the water fraction may be an active component of the FLL extract that exerts beneficial effects on improving bone metabolism via regulating vitamin D metabolism in kidney and vitamin D-dependent calcium transporters in duodenum as well as modulating the expression of CaSR in the parathyroid gland and kidneys.

Differential response of bone and kidney to ACEI in db/db mice: A potential effect of captopril on accelerating bone loss.

The components of renin-angiotensin system (RAS) are expressed in the kidney and bone. Kidney disease and bone injury are common complications associated with diabetes. This study aimed to investigate the effects of an angiotensin-converting enzyme inhibitor, captopril, on the kidney and bone of db/db mice. The db/db mice were orally administered by gavage with captopril for 8weeks with db/+ mice as the non-diabetic control. Serum and urine biochemistries were determined by standard colorimetric methods or ELISA. Histological measurements were performed on the kidney by periodic acid-schiff staining and on the tibial proximal metaphysis by safranin O and masson-trichrome staining. Trabecular bone mass and bone quality were analyzed by microcomputed tomography. Quantitative polymerase chain reaction and immunoblotting were applied for molecular analysis on mRNA and protein expression. Captopril significantly improved albuminuria and glomerulosclerosis in db/db mice, and these effects might be attributed to the down-regulation of angiotensin II expression and the expression of its down-stream profibrotic factors in the kidney, like connective tissue growth factor and vascular endothelial growth factor. Urinary excretion of calcium and phosphorus markedly increased in db/db mice in response to captopril. Treatment with captopril induced a decrease in bone mineral density and deterioration of trabecular bone at proximal metaphysis of tibia in db/db mice, as shown in the histological and reconstructed 3-dimensional images. Even though captopril effectively reversed the diabetes-induced changes in calcium-binding protein 28-k and vitamin D receptor expression in the kidney as well as the expression of RAS components and bradykinin receptor-2 in bone tissue, treatment with captopril increased the osteoclast-covered bone surface, reduced the osteoblast-covered bone surface, down-regulated the expression of type 1 collagen and transcription factor runt-related transcription factor 2 (markers for osteoblastic functions), and up-regulated the expression of carbonic anhydrase II (marker for bone resorption). Captopril exerted therapeutic effects on renal injuries associated with type 2 diabetes but worsened the deteriorations of trabecular bone in db/db mice; the latter of which was at least in part due to the stimulation of osteoclastogenesis and the suppression of osteogenesis by captopril.