Figure 1
From: Serotonin: a novel bone mass controller may have implications for alveolar bone
Diagram depicting the two alternative models for Lrp5 action. According to the former, “central”, serotonin-mediated model (left-hand side), activation of Lrp5 inhibits Tryptophan Hydroxylase 1 (Tph1) and reduces circulating levels of Serotonin, thus decreasing its inhibitory effect on osteoblasts via its HTR1B receptor. According to the “peripheral” serotonin-independent model (right-hand side), Lrp5 acts directly on osteoblasts initiating the canonical Wnt signal cascade and inducing beta catenin translocation to the nucleus and activation of its transcriptional program.