RESUMEN
Objective To investigate the inhibition of rutaecarpine (Rut) on left ventricular hypertrophy rat induced by abdominal aorta coarctation (AAC) and further explore the potential mechanisms. Methods Left ventricular hypertrophy was induced by AAC in male Sprague-Dawley rats.Fifty rats were randomly divided into five groups:model control group,sham operation group,low-,middle- and high-dose (10,20,40 mg?kg-1?d-1 ) Rut group,with 10 rats of each group.Rut was administrated by gavage once daily from the first day after operation for consecutive 4 weeks.The sham operation and model groups were administrated with equal volume of 0.9％ sodium chloride solution.The hemodynamics parameters were detected by BL-420 E biology function laboratory system,and the left ventricular hypertrophy index (LVHI,left ventricular weight/ body weight) was measured at 8 h after administration of the last dose.The pathological changes of left ventricular hypertrophy were evaluated by HE staining.To elucidate the mechanism of protection,the mRNA expressions of atrial natriuretic factor ( ANF),extracellular signal-regulated kinase 2 (ERK2) and MAPK phosphatase-1 (MKP-1) were analyzed by real time RT-PCR,and the protein expressions of MKP-1 and phosphorylated ERK2 (p-ERK2) were examined by Western blotting. Results Left ventricular hypertrophy induced by AAC was evidenced by the increased left ventricular weight (LVW) and LVHI (P<0.01),the decreased± dp/ dt max (P<0.01),and the elevated expression of ANF (P<0.01).Compared with model control,Rut (20,40 mg?kg-1?d-1 ) treatment significantly attenuated AAC-induced rat left ventricular hypertrophy,decreased the LVHI (P<0.05),left ventricular systole pressure (LVSP),and left ventricular end diastolic pressure ( LVEDP ) ( P < 0. 05), and increased ± dp/ dtmax ( P < 0. 01). In addition, Rut ( 20, 40 mg?kg-1?d-1 ) downregulated the expression of ANF,ERK2 mRNA,and ERK2 protein,but upregulated the MKP-1 mRNA and protein expression.However,Rut low-dose (10 mg?kg-1 ?d-1 ) was ineffective (P> 0.05). Conclusion Rut alleviates left ventricular hypertrophy induced by abdominal aorta coarctation,and the protection appears to be due,at least in part,to its inhibitory effects on the MAPK/ ERK signal pathway.
RESUMEN
Recent studies suggest a critical role of osteocytes in controlling skeletal development and bone remodeling although the molecular mechanism is largely unknown. This study investigated BMP signaling in osteocytes by disrupting Bmpr1a under the Dmp1-promoter. The conditional knockout (cKO) mice displayed a striking osteosclerotic phenotype with increased trabecular bone volume, thickness, number, and mineral density as assessed by X-ray and micro-CT. The bone histomorphometry, H&E, and TRAP staining revealed a dramatic increase in trabecular and cortical bone masses but a sharp reduction in osteoclast number. Moreover, there was an increase in BrdU positive osteocytes (2-5-fold) and osteoid volume (~4-fold) but a decrease in the bone formation rate (~85%) in the cKO bones, indicating a defective mineralization. The SEM analysis revealed poorly formed osteocytes: a sharp increase in cell numbers, a great reduction in cell dendrites, and a remarkable change in the cell distribution pattern. Molecular studies demonstrated a significant decrease in the Sost mRNA levels in bone (>95%), and the SOST protein levels in serum (~85%) and bone matrices. There was a significant increase in the ß-catenin (>3-fold) mRNA levels as well as its target genes Tcf1 (>6-fold) and Tcf3 (~2-fold) in the cKO bones. We also showed a significant decrease in the RANKL levels of serum proteins (~65%) and bone mRNA (~57%), and a significant increase in the Opg mRNA levels (>20-fold) together with a significant reduction in the Rankl/Opg ratio (>95%), which are responsible for a sharp reduction in the cKO osteoclasts. The values of mechanical strength were higher in cKO femora (i.e. max force, displacement, and work failure). These results suggest that loss of BMP signaling specifically in osteocytes dramatically increases bone mass presumably through simultaneous inhibition of RANKL and SOST, leading to osteoclast inhibition and Wnt activation together. Finally, a working hypothesis is proposed to explain how BMPR1A controls bone remodeling by inhibiting cell proliferation and stimulating differentiation. It is reported that RANKL and SOST are abundantly expressed by osteocytes. Thus, BMP signaling through BMPR1A plays important roles in osteocytes.