Defects in growth and bone metabolism in klotho mutant mice are resistant to GH treatment.
Klotho mutant (kl/kl) mice exhibit growth retardation after weaning, and previous electron microscopic examination of GH-producing cells in pituitary glands revealed a reduction in GH granules. However, it has not been known whether growth retardation in klotho mutant mice is related to the loss of GH function. We therefore examined whether treatment with GH could rescue the retardation of growth. At the end of 3 weeks of treatment with human GH, the body weight of wild-type (WT) mice was increased. In contrast, body weight was not increased in klotho mutant mice even after the treatment with human GH. Another feature of klotho mutant mice is the presence of osteopetrosis in the epiphyses of long bones and vertebrae. Treatment with human GH increased trabecular bone volume in the epiphyseal region of WT tibiae. Interestingly, increase in trabecular bone volume by GH treatment was also observed in klotho mutant mice and, therefore, the phenotype of high bone volume in the klotho mice was further enhanced. These findings indicate that a GH receptor system in cancellous bones could operate in mutant mice. Thus, growth retardation in the klotho mutant mice is resistant against GH treatment even when these mice respond to GH treatment in terms of cancellous bone volume.
Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Kanda Surugadai 2-3-10, Chiyoda-ku, Tokyo 101-0062, Japan.
K
K
Kashimada
T
T
Yamashita
K
K
Tsuji
A
A
Nifuji
S
S
Mizutani
Y
Y
Nabeshima
M
M
Noda
D000818:Animals; D001823:Body Composition / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D006130:Growth Disorders / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D019382:Human Growth Hormone / Q000627:therapeutic use*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D023421:Models, Animal; D013977:Tibia / Q000000981:diagnostic imaging / Q000503:physiopathology; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure
D019382:Human Growth Hormone