Implication for melatonin and its receptor in the spinal deformities of hereditary Lordoscoliotic Rabbits.
METHODS
The association between melatonin system and the spontaneous development of the spinal deformities in the Hereditary Lordoscoliotic Rabbit, the natural animal model for idiopathic scoliosis, was studied.


OBJECTIVE
To examine the implication for melatonin and its receptor in the spinal deformities of the natural animal model, the Hereditary Lordoscoliotic Rabbit.


BACKGROUND
We previously reported radiologic and histologic studies investigating the etiology of spinal deformities in a breed of Japanese White Rabbit, the Hereditary Lordoscoliotic Rabbit. These animals develop thoracic lordoscoliosis during growth and as such can be used as a model for human idiopathic scoliosis. Although previous studies in chickens have established that pinealectomy produces scoliosis, the cause of the condition is yet to be fully elucidated.


METHODS
Serum melatonin levels in Hereditary Lordoscoliotic Rabbits were measured by radioimmunoassay and compared with those of Japanese White Rabbits (controls). The expression of melatonin receptor in the rabbit was detected by homology cloning to access the number of the melatonin receptor mRNA in the rabbit spinal cord by quantitative reverse-transcribed polymerase chain reaction.


RESULTS
Serum melatonin levels in Hereditary Lordoscoliotic Rabbits were significant higher than those of controls in each period until 20 weeks. We detected the expression of melatonin receptor mRNA in rabbit spinal cord. However, no significant quantitative differences were found in the level of expression of melatonin mRNA in the spinal cord between Hereditary Lordoscoliotic Rabbits and controls.


CONCLUSIONS
In relation to the present study, we suggest that causes of spinal deformities in the Hereditary Lordoscoliotic Rabbit may be the result of the contribution of melatonin receptors as well as that of altered serum melatonin levels in the Hereditary Lordoscoliotic Rabbit. Further studies will be required to investigate the expression of melatonin receptor in other tissues of the Hereditary Lordoscoliotic Rabbit as well as to delineate the role of melatonin in the pathogenesis of idiopathic scoliosis.
Sobajima
Satoshi
S
Department of Orthopedic Surgery, Osaka Medical College, Osaka, Japan. skun75@aol.com
Kin
Akihiro
A
Baba
Ichiro
I
Kanbara
Kiyoto
K
Semoto
Yoshihiro
Y
Abe
Muneaki
M
D000367:Age Factors; D000818:Animals; D004195:Disease Models, Animal; D008141:Lordosis / Q000235:genetics / Q000378:metabolism; D008550:Melatonin / Q000097:blood*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism*; D044094:Receptors, Melatonin; D012160:Retina / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012600:Scoliosis / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013116:Spinal Cord / Q000378:metabolism; D013121:Spinal Curvatures / Q000235:genetics* / Q000378:metabolism*
D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D044094:Receptors, Melatonin; D008550:Melatonin