Luteolin Stimulates Proliferation and Inhibits Late Differentiation of Primary Rat Calvarial Osteoblast Induced by High-dose Dexamethasone via Sema3A /NRP1/Pleixin A1.

Abstract

Although Semaphorin 3A (Sema3A)/ Neuropilin-1(NRP1)/Plexin A1 is one of the important targets in bone metabolism, few studies are performed on this target in the glucocorticoids- induced osteoporosis. Luteolin is a chemical component of Honeysuckle and it has various bioactivities. The effect of Luteolin on the glucocorticoids-induced osteoporosis (primary osteoblasts model) remain unknown. The aim of this study was to investigate the action of Sema3A/ NRP1/Plexin A1 in Luteolin- induced osteoprotection against high-dose Dexamethasone. The effect of Luteolin on the proliferation, late differentiation, and apoptosis of primary osteoblasts model of glucocorticoids-induced osteoporosis in vitro as well as the expression of Sema3A/ NRP1/Plexin A1 are investigated by using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-Htetrazolium bromide, Cell Counting Kit-8, reverse transcription-quantitative real-time polymerase chain reaction, western bolting and so on. Suckling SD rats' calvarial osteoblasts were isolated and identified. The glucocorticoidsinduced primary osteoporosis cell model was established by 100 μM Dexamethasone in 48 h (P<0.01). Luteolin promotes osteoblasts either in physiological condition (without Dexamethasone) or pathological condition (with Dexamethasone) at 1 μM concentration for 48h (P<0.01). Luteolin partly reverses down-regulated expression of proliferation markers such as proliferating cell nuclear and CyclinD1. (P<0.01) Similarly, Luteolin partly reverses up-regulated expression of apoptosis markers such as Bax/B-cell lymphoma-2. (P<0.01) The expression of mRNA and protein of Sema3A/ NRP1/Plexin A1 decreased in model one which significantly increased in Luteolin protecting one. (P<0.05) Interestingly, the late differentiation marker such as osteocalcin and collagenase Ⅰ sharply decreased in Luteolin protecting group compared with model one. (P<0.01). The thesis concludes that Luteolin promoted the proliferation of osteoblast and inhibited its apoptosis and late differentiation in this glucocorticoids-induced primary osteoporosis cell model. This function may be related to the expression of up-regulated Sema3A/NRP1/Plexin A1. Therefore, Luteolin may be a potential medicine for the glucocorticoids-induced osteoporosis.