Ethnopharmacological relevance: Fructus Ligustri Lucidi (FLL), the fruit of Ligustrum lucidum Ait, is a commonly prescribed herb to nourish the endocrine and renal systems and to strengthen the bones in Traditional Chinese Medicine. This study was aimed to determine the effects of water fraction of FLL ethanol extract (WF-EE) on urinary calcium excretion and trabecular bone properties in type 1 diabetic mice.
Materials and methods: The DBA/2J mice with type 1 diabetes induced by streptozotocin injection were orally administered with WF-EE. After 6 weeks of treatment, the level of biomarkers, including serum calcium, parathyroid hormone (PTH), and fibroblast growth factor-23 (FGF-23) and urine calcium, was measured. Micro-CT was performed to detect trabecular bone properties of the proximal tibial metaphysis. The expression of active calcium transporting proteins in kidney and duodenum was determined by RT-PCR, immunoblotting and immunostaining.
Results: Type 1 diabetes induced hypercalciuria and trabecular bone deterioration. The WF-EE could significantly inhibit hypercalciuria and ameliorate the micro-structure of trabecular bone as well as increase serum PTH and FGF-23 levels in type 1 diabetic mice. The gene expressions of active calcium transporting proteins in duodenum were up-regulated, and the gene and protein expressions of calcium-sensing receptor (CaSR) in kidney were dramatically down-regulated in diabetic mice in response to the treatment with WF-EE.
Conclusions: The present study demonstrated the protective effects of the water fraction of Fructus Ligustri Lucidi ethanol extract against hypercalciuria and trabecular bone deterioration in experimentally type 1 diabetic mice, and the underlying mechanism may be attributed to its regulations on duodenal calcium transporting proteins and renal CaSR.
Keywords: Calcium; Calcium-sensing receptor; Diabetes; Fructus Ligustri Lucidi; Kidney; Trabecular bone.
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