Disproportional body growth in female estrogen receptor-α-inactivated mice

Estrogens play an important role in the regulation of longitudinal bone growth in man, as demonstrated by recent descriptions of individuals with estrogen insensitivity or aromatase deficiency. Two estrogen receptors, ER alpha and ER beta, have been cloned. The aim of the present study was to investigate the function of ER alpha in the regulation of body growth and skeletal growth. Adult female mice with inactivated ER alpha (ER alpha-/-) demonstrated an increased body weight compared with wild-type mice (114% of control). However, the length of the appendicular skeleton was decreased in adult ER alpha-/- mice (femur 93% of control). In contrast, the axial skeleton was normal (crown-rump length 98% of control). The decreased growth of the appendicular skeleton was associated with decreased serum levels of IGF-I (77% of control), indicating that the GH/IGF-I axis may be involved in the decreased longitudinal bone growth seen in female ER alpha-/- mice. (C) 1999 Academic Press.