The use of LP533401 as a therapeutic option for renal osteodystrophy affects, renal calcium handling, vitamin D metabolism and bone health in uremic rats.

BACKGROUND: Klotho is a key regulator of phosphate and Ca2+ - transport in the kidney. Recently, we showed that treatment with LP533401 improved bone health in rats with chronic kidney disease (CKD) via the normalization of serum phosphate resulting from the reduced renal expression of phosphate co-transporters, including Klotho.

METHODS: We evaluated the effect of LP533401 therapy on Klotho-expression dependent Ca2+ - transporters, renal calcium handling and the potential consequences for the bone of uremic rats.

RESULTS: Treatment with LP533401 and its vehicle, resulted in the inhibition of transient receptor potential vanilloid receptor subtypes 5 and 6 (TRPV5, TRPV6) and calbidin (CaBP-28k, CaBP-9k) expression. The compensatory acceleration in renal expression of Na+/Ca2+ -exchanger (NCX1), 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1), the intensification of vitamin D metabolism and disruption of sophisticated balance between 1,25-dihydroxyvitamin D - serotonin was observed, especially in rats treated with LP533401. The imbalance between 1,25-dihydroxyvitamin D - serotonin levels led to intensified bone remodeling and improvement in bone geometry, mineral status and strength in animals treated with LP533401.

CONCLUSION: The modulation of circulating serotonin and its relation to other regulators of calcium handling can play an important role in calcium homeostasis and bone integrity in CKD rats treated with LP533401.