Table 1.

Genetically engineered mouse models for analyzing skeletal action of serotonin

Mouse		Skeletal phenotype	Reference
5-HTT−/−	Global knock out of serotonin transporter	Low bone mass, low bone formation	20
Tph1gut−/−	Gut-specific Tph1 knock out under villin promoter	Reduced serotonin levels in the gut High bone mass, increased bone formation	21
Tph1do−/−	Osteoblasts specific Tph1 knock out under al(I)Col promoter	Minimal increase in bone mass	21
Htr1b−/−	Global knock out of Htr1b. Htr1b is the most abundantly expressed serotonin receptor in osteoblasts	High bone mass, increased bone formation	21
Tph2−/−	Global knock out of Tph2	No detectable serotonin in the CNS Low bone mass, low bone formation, increased bone resorption	19
Htr2c−/−	Global knock out of Htr2c. Htr2c is most abundantly expressed in the hypothalamus	Low bone mass, low bone formation, increased bone resorption High sympathetic activity	19

5-HTT, 5-HT(5-hydroxytryptamine) transporter; Tph, tryptophan hydroxylase; Htr, 5-HT receptor.