MONDAY, Oct. 16 (HealthDay News) -- In mice, fluoxetine increases bone mass under normal physiologic and inflammatory conditions, but does not prevent bone loss associated with estrogen deficiency, according to a study published online Oct. 13 in the Journal of Cellular Biochemistry.
Ricardo Battaglino, Ph.D., of the Forsyth Institute in Boston, and colleagues treated laboratory mice with fluoxetine for six weeks.
Under normal physiologic conditions, the researchers found that fluoxetine increased trabecular bone volume and total volume in femurs and vertebrae. Under inflammatory conditions induced by injections of lipopolysaccharide, fluoxetine stimulated new bone formation and a net gain in bone mass. However, fluoxetine did not protect against bone loss after ovariectomy, suggesting that its anabolic effect requires the presence of estrogen.
"Mounting evidence exists for the operation of a functional serotonin (5-HT) system in osteoclasts and osteoblasts, which involves both receptor activation and 5-HT reuptake," the authors write. "In previous work we showed that the serotonin transporter (5-HTT) is expressed in osteoclasts and that its activity is required for osteoclast differentiation in vitro. These [new] data suggest that commonly used antidepressive agents may affect bone mass."