This work studies the depression-osteoporosis relationship, with the aim of focusing on depressive disorders that concern the quantitative dynamic of platelet membrane viscosity and interactome cytoskeleton modifications (in particular Tubulin and Gsα protein) as a possible condition of the involvement of the serotonin axis (gut, brain and platelet), not only in depression but also in connection with osteoporosis. Here, GNAS is linked to major depressive disorder.