Comparison between two experimental protocols to promote osteoporosis in the maxilla and proximal tibia of female rats.
The effects of two experimental protocols (ovariectomy associated or not with a low calcium diet) used to promote osteoporosis in the rat maxilla and proximal tibia were compared 5 and 11 weeks after surgery. Female Wistar rats were ovariectomized or sham-operated. Half of the ovariectomized rats were fed a low Ca++ diet (ovx*) and the remaining ovariectomized (ovx) and sham animals received a standard chow. At sacrifice, the proximal metaphysis was excised from the tibia and the molars were extracted from the hemi-maxilla. Dry (60 degrees C overnight) and ash (700 degrees C/14 h) weights were measured and the ashes were used for Ca++ measurement by means of a colorimetric method. After 5 weeks, ovx caused no alteration while ovx* decreased proximal metaphysis (17%) and maxilla (35%) bone mass. After 11 weeks, ovx caused a 14% bone mass reduction in the proximal metaphysis but not in the maxilla, while ovx* caused a comparable bone mass reduction (30%) in both bone segments. Calcium concentration was not altered in any experimental condition. The results show that estrogen deficiency is insufficient to cause maxillary osteoporosis in rats over an 11-week period and a long-term ovariectomy is needed to exert deleterious effect on proximal metaphysis bone mass. When a low Ca++ diet is associated with estrogen deficiency, however, a relatively precocious harmful effect is observed, twice as pronounced in the maxilla than in the proximal metaphysis. On a long-term basis, ovariectomy associated with a low Ca++ diet seems to be equally injurious to both proximal metaphysis and maxilla.
Teófilo
Juliana Mazzonetto
JM
Oral Rehabilitation Area, School of Dentistry of Ribeirão Preto.
Azevedo
Ana Carolina Bernardes
AC
Petenusci
Sérgio Olavo
SO
Mazaro
Renata
R
Lamano-Carvalho
Teresa Lúcia
TL
D016301:Alveolar Bone Loss / Q000209:etiology*; D000818:Animals; D015519:Bone Density / Q000502:physiology; D002118:Calcium / Q000172:deficiency; D002136:Calcium, Dietary / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004967:Estrogens / Q000172:deficiency; D005260:Female; D008437:Maxilla / Q000503:physiopathology; D008439:Maxillary Diseases / Q000209:etiology*; D010024:Osteoporosis / Q000209:etiology*; D010052:Ovariectomy / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric; D013977:Tibia / Q000503:physiopathology
D002136:Calcium, Dietary; D004967:Estrogens; D002118:Calcium