Effects of 275 nm and 310 nm ultraviolet irradiation on bone metabolism in ovariectomized osteoporotic rats / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effect of 275 nm and 310 nm ultraviolet irradiation on ovariectomized rats' bone metabolism.@*METHODS@#Twenty four 3-month-old female Sprague-Dawley (SD) rat were randomly divided into control group, sham operated group, 275 nm ultraviolet (UV) irradiation group and 310 nm UV irradiation group. Each group contained 6 rats. The rats in the two irradiation groups were treated with bilateral ovariectomy. The rats in sham operated group received sham operation (They were given the same back incision and a bit of par-ovarian fat were removed). Control group received no disposition. About 24 weeks after operation, all the rats received detailed bone mineral density (BMD) detection again. Detection regions include cervical vertebra, lumbar vertebra, proximal femur, mid femur and distal femur. Next, osteopenia rats in 275 nm irradiation group were UV irradiated 275 nm with fixed illumination intensity (15 μW/cm2) everyday for 16 weeks. The osteopenia rats in 310 nm irradiation group were UV irradiated 310 nm with fixed illumination intensity (15 μW/cm2) everyday for 16 weeks. The backs of the rats were shaved regularly as irradiation area (6 cm×8 cm). After 16-week irradiation, all the rats' BMD of cervical vertebra, lumbar vertebra, proximal femur, mid femur and distal femur were measured. At the end of the trial, all the rats' blood specimens were obtained and serum 25(OH)D, procollagen type Ⅰ N-peptide (PINP) and osteocalcin (OC) were measured.@*RESULTS@#Compared with control group [(238.78±26.74) mg/cm3], the BMD of the whole body were significantly lower in 275 nm [(193.34±13.28) mg/cm3] and 310 nm [(191.19±18.48) mg/cm3] irradiation groups (P=0.002, P=0.001). There were no significant difference between sham operated group [(227.20±14.32) mg/cm3] and control group. After 16-week ultraviolet irradiation, the BMD of the whole body were significantly increased in 275 nm [(193.34±13.28) mg/cm3 vs. (221.68±25.52) mg/cm3, P=0.005] and 310 nm groups [(191.19±18.48) mg/cm3 vs. (267.48±20.54) mg/cm3, P < 0.001] after corresponding irradiation. The BMD of the four body regions (lumbar vertebra, proximal femur, mid femur and distal femur) had significantly increased after irradiation in 275 nm irradiation group. For 310 nm irradiation group, the BMD in cervical vertebra, lumbar vertebra, proximal femur, mid femur and distal femur also had increased significantly after 310 nm ultraviolet irradiation. The concentration of serum 25(OH)D and OC was higher in 275 nm irradiation group than in control group [(46.78±5.59) μg/L vs. (21.32±6.65) μg/L, P=0.002;(2.05±0.53) U/L vs. (1.32±0.07) U/L, P=0.022]. Compared with the control, the concentration of serum 25(OH)D [(58.05±12.74) μg/L], OC [(2.04±0.53) U/L] and PINP [(176.16±24.18) U/L] was significantly higher (P < 0.001, P=0.015, P=0.005) in 310 nm irradiation group. However, there were no significantly difference between sham operated group and the control.@*CONCLUSION@#Both 275 nm and 310 nm ultraviolet could improve rats' vitamin D synthesis. Both 275 nm and 310 nm ultraviolet could improve osteopenia rats' bone condition. The irradiation of 310 nm might be more effective on bone condition improvement.

Inhibitory effect of Astragalus polysaccharide on osteoporosis in ovariectomized rats by regulating FoxO3a /Wnt signaling pathway

Abstract Purpose: To investigate inhibitory effect of Astragalus polysaccharide (APS) on osteoporosis in ovariectomized rats by regulating FoxO3a/Wnt2 signaling pathway. Methods: Postmenopausal osteoporosis (PMOP) animal model was developed by excising the bilateral ovaries of rats. The model rats were administered with APS (200 mg/kg, 400 mg/kg, 800 mg/kg) by intragastric administration once daily for 12 weeks. Bone density, bone metabolism index and oxidative stress index were measured in all groups. Furthermore, the regulation of APS of FoxO3a / Wnt2 signaling pathway was observed. Results: APS has an estrogen-like effect, which can increase bone mass, lower serum ALP and BGP values, increase blood calcium content, and increase bone density of the femur and vertebrae in rats. At the same time, APS can increase the bone mineral content of the femur, increase the maximum stress, maximum load and elastic modulus of the ovariectomized rats, improve oxidative stress in rats by increasing the gene expression of β-catenin and Wnt2 mRNA and inhibiting the gene expression of FoxO3a mRNA. Conclusion: Astragalus polysaccharide can effectively alleviate oxidative stress-mediated osteoporosis in ovariectomized rats, which may be related to its regulation of FoxO3a/Wnt2/β-catenin pathway.

Influence of low-level laser irradiation on osteocalcin protein and gene expression in bone tissue1

Abstract Purpose: To evaluate osteocalcin gene and protein expression in vitro and in an in vivo model of ostectomy. Methods: Twenty Wistar rats were assigned into two groups A (n=10, laser) and B (n=10, control). Ostectomy was performed in the femur diaphysis; the twenty fragments removed, composed in vitro groups named as in vivo (A and B) and cultivated in CO2 atmosphere for thirteen days. Low-level laser irradiation was performed in groups A (in vivo and in vitro) by an GaAlAs device (λ=808 nm, dose of 2J/cm2, power of 200mW, power density of 0.2W/cm2, total energy of 1.25J, spot diameter of 0.02mm) for 5 seconds, at one point, daily. It was performed immunocytochemistry assays in vivo and in vitro groups. In vitro groups were also submitted to RNA extraction, cDNA synthesis and gene expression by quantitative PCR. Statistical analysis was realized with p<0.05. Results: Immunocytochemistry scores showed no significant differences between control and laser groups either in vivo and in vitro. Gene expression also showed no statistical differences. Conclusion: Low-level laser irradiation did not alter osteocalcin protein and gene expression in vivo and in vitro in the studied period but it may have been expressed them in an earlier period.

Association between undercarboxylated osteocalcin, bone mineral density, and metabolic parameters in postmenopausal women

ABSTRACT Objective: Osteocalcin has been associated with several effects on energy and glucose metabolism. However, the physiological role of undercarboxylated osteocalcin (U-osc; the hormonally active isoform of osteocalcin) is still controversial. To correlate the serum levels of U-osc with bone mineral density (BMD) values and metabolic parameters in postmenopausal women. Subjects and methods: Cross-sectional study including 105 postmenopausal women (age 56.5 ± 6.1 years, body mass index [BMI] 28.2 ± 4.9 kg/m2) grouped based on the presence of three or less, four, or five criteria of metabolic syndrome according to the International Diabetes Federation (IDF). The subjects underwent dualenergy x-ray absorptiometry (DXA) for the assessment of body composition and BMD and blood tests for the measurement of U-osc and bone-specific alkaline phosphatase (BSAP) levels. Results: The mean U-osc level was 3.1 ± 3.4 ng/mL (median 2.3 ng/mL, range 0.0-18.4 ng/mL) and the mean BSAP level was 12.9 ± 4.0 ng/mL (median 12.1 ng/mL, range 73-24.4 ng/mL). There were no associations between U-osc and BSAP levels with serum metabolic parameters. Lower fasting glucose levels were observed in participants with increased values of U-osc/femoral BMD ratio (3.61 ± 4 ng/mL versus 10.2 ± 1.6 ng/mL, p = 0.036). When the participants were stratified into tertiles according to the U-osc/ femoral BMD and U-osc/lumbar BMD ratios, lower fasting glucose levels correlated with increased ratios (p = 0.029 and p = 0.042, respectively). Conclusion: Based on the ratio of U-osc to BMD, our study demonstrated an association between U-osc and glucose metabolism. However, no association was observed between U-osc and metabolic parameters.The U-osc/BMD ratio is an innovative way to correct the U-osc value for bone mass.

Role of Triticum aestivum aqueous extract in glucocorticoid induced osteoporosis in rats.

Administration of aqueous extract of T. aestivum (200 and 400 mg/kg/day, po, for 30 days) and risedronate (20 mg/kg, sc, five times a week for 30 days) following methyl prednisolone sodium succinate (10 mg/kg, sc, thrice a week for 4 weeks) induced osteoporosis in Wistar rats showed an increase in the serum levels of bone mineral content markers, decrease in the serum and urinary levels of bone resorption markers. An incline in strength of femur and tibia was seen particularly with 400 mg/kg of T. aestivum. Maintenance of calcium homeostasis, formation of collagen and scavenging of free radicals can plausibly be the mode of action of aqueous extract of T. aestivum thereby combating osteoporosis induced by glucocorticoids.

Are skeletally mature female rats a suitable model to study osteoporosis? / Ratas esqueleticamente maduras são um modelo satisfatório para estudar osteoporose?

OBJECTIVE: To analyze if female Wistar rats at 56 weeks of age are a suitable model to study osteoporosis. MATERIALS AND METHODS: Female rats with 6 and 36 weeks of age (n = 8 per group) were kept over a 20-week period and fed a diet for mature rodents complete in terms of Ca, phosphorous, and vitamin D. Excised femurs were measured for bone mass using dual-energy x-ray absorptiometry, morphometry, and biomechanical properties. The following serum mar-kers of bone metabolism were analyzed: parathyroid hormone (PTH), osteocalcin (OC), osteoprotegerin (OPG), receptor activator of nuclear factor Κappa B ligand (RANKL), C-terminal peptides of type I collagen (CTX-I), total calcium, and alkaline phosphatase (ALP) activity. RESULTS: Rats at 56 weeks of age showed important bone metabolism differences when compared with the younger group, such as, highest diaphysis energy to failure, lowest levels of OC, CTX-I, and ALP, and elevated PTH, even with adequate dietary Ca. CONCLUSION: Rats at 26-week-old rats may be too young to study age-related bone loss, whereas the 56-week-old rats may be good models to represent the early stages of age-related changes in bone metabolism.

OBJETIVO: Avaliar se ratas Wistar com 56 semanas de idade são um modelo satisfatório para estudar osteoporose. MATERIAIS E MÉTODOS: Ratas com 6 e 36 semanas de idade (n = 8 por grupo) foram criadas por um período de 20 semanas e alimentadas com dieta completa em Ca, fósforo e vitamina D para ratas adultas. Os fêmures foram analisados quanto à massa óssea pela técnica de absortiometria por dupla fonte de raios-X, morfometria e propriedades biomecânicas; os marcadores séricos do metabolismo ósseo analisados foram paratormônio (PTH), osteocalcina (OC), osteoprotegerina (OPG), fator receptor ativador nuclear Κappa B ligante (RANKL), peptídeos C-terminal de colágeno tipo I (CTX-I), cálcio total e atividade da fosfatase alcalina (FA). RESULTADOS: As ratas com 56 semanas de vida apresentaram uma importante diferença no metabolismo ósseo quando comparadas ao grupo das ratas jovens, como, por exemplo, maior energia para quebrar a diáfise do fêmur, menores níveis de OC, CTX-I e ALP e maiores níveis de PTH mesmo com dieta adequada em cálcio. CONCLUSÃO: As ratas com 26 semanas de vida podem ser consideradas muito jovens para estudar a perda óssea relacionada à idade, porém, as ratas com 56 semanas de vida podem representar um bom modelo dos estágios iniciais das alterações associadas à idade no metabolismo ósseo.

Biodistribution of technetium-99m pertechnetate after Roux-en-Y gastric bypass (Capella technique) in rats / Biodistribuição de tecnécio-99m pertecnetato após desvio gástrico em Y de Roux (técnica de Capella) em ratos

PURPOSE: The biodistribution of sodium pertechnetate, the most used radiopharmaceutical in nuclear medicine, has not been studied in details after bariatric surgery. The objective was to investigate the effect of Roux-en-Y gastric bypass (RYGB) on biodistribution of sodium pertechnetate (Na99mTc-) in organs and tissues of rats. METHODS: Twelve rats were randomly divided into two groups of 6 animals each. The RYGB group rats were submitted to the Roux-en-Y gastric bypass and the control group rats were not operated. After 15 days, all rats were injected with 0.1mL of Na99mTc- via orbital plexus with average radioactivity of 0.66 MBq. After 30 minutes, liver, stomach, thyroid, heart, lung, kidney and femur samples were harvested, weighed and percentage of radioactivity per gram ( percentATI/g) of each organ was determined by gama counter Wizard Perkin-Elmer. We applied the Student t test for statistical analysis, considering p<0.05 as significant. RESULTS: Significant reduction in mean percentATI/g was observed in the liver, stomach and femur in the RYGB group animals, compared with the control group rats (p<0.05). In other organs no significant difference in percentATI/g was observed between the two groups. CONCLUSION: This work contributes to the knowledge that the bariatric surgery RYGB modifies the pattern of biodistribution of Na99mTc-.

OBJETIVO: Avaliar o efeito da cirurgia de desvio gástrico em Y de Roux (BGYR) na biodistribuição do pertecnetato de sódio (Na99mTc) em órgãos e tecidos de ratos. MÉTODOS: Doze ratos Wistar foram aleatoriamente distribuidos em dois grupos de seis animais cada. O grupo BGYR foi submetido a técnica cirúrgica do desvio gástrico em Y de Roux e o grupo controle não foi operado. No 15º dia de pós-operatório foi administrado 0,1 ml IV de Na99mTc aos animais dos dois grupos, com atividade radioativa média de 0,66MBq. Após 30 minutos os ratos foram mortos e retirados fragmentos de fígado, estômago, tireóide, coração, pulmão, rim e fêmur. As amostras foram lavadas com solução salina 0,9 por cento pesadas e submetidas ao Contador Gama 1470, WizardTM Perkin-Elmer para se determinar o percentual de atividade radiotiva por grama ( por centoATI/g) de cada órgão. Empregou-se o teste t de Student para análise estatística, considerando p<0,05 como significante. RESULTADOS: Redução significante na média de por centoATI/g foi observada no fígado, estômago e fêmur nos animais submetidos a cirurgia de BGYR comparado com o grupo controle (p<0,05). Nos demais órgãos não houve diferença significante no por centoATI/g entre os dois grupos. CONCLUSÃO: A cirurgia BGYR em ratos modificou a biodistribuição do Na99mTc em alguns órgãos, podendo ter implicações clínicas na interpretação de exames cintilográficos.

Bone structure, strength and microhardness resulting after hindlimb unloading in rats

Introduction: Bone strength is influenced by a number of different determinants, such as mass, size, geometry and also by the intrinsic material properties of the tissue. Aims: The structure and mechanical properties of the femur were analyzed in aged (14 mo-old) animals submitted to hindlimb unloading (HU) for 21 days. Methods: Twenty Wistar rats were randomly divided into Control and HU groups and the femur was submitted to dual X ray absorptiometry (DXA), DIGORA radiographic density, mechanical compression testing and Knoop microhardness analyse in cortical and cancellous bone. Results: Femurs from HU group presented significantly lower failure load, decreased bone mineral density (BMD)/bone mineral content (BMC) in whole bone; proximal/distal epiphysis and middiaphyseal cortical bone measured by DXA were similar in the two groups; radiographic density from areas in proximal epiphysis was significantly lower in HU group, and microhardness measured at periosteal and endosteal levels were also significantly diminished in HU compared with Control group. Conclusion: Disuse induced damage in the trabecular femoral bone architecture with decisive effect on the head and trochanteric fossa, which became weaker. Bone diaphyseal cortical hardness also suffered effect of unloading, probably related to osteocyte/osteoblast activity.

Does Quantitative Tibial Ultrasound Predict Low Bone Mineral Density Defined by Dual Energy X-Ray Absorptiometry?

PURPOSE: Efforts for the early detection of bone loss and subsequent fracture risk by quantitative ultrasound (QUS), which is a non-invasive, radiation free, and cheaper method, seem rational to reduce the management costs. We aimed in this study to assess the probable correlation of speed of sound (SOS) values obtained by QUS with bone mineral density (BMD) as measured by the gold standard method, dual energy X-ray absorptiometry (DEXA), and to investigate the diagnostic value of QUS to define low BMD. MATERIALS AND METHODS: One hundred twenty-two postmenopausal women having prior standard DEXA measurements were included in the study. Spine and proximal femur (neck, trochanter and Ward's triangle) BMD were assessed in a standard protocol by DEXA. The middle point of the right tibia was chosen for SOS measurement by tibial QUS. RESULTS: The SOS values were observed to be significantly higher in the normal BMD (t score >-1) group at all measurement sites except for the lumbar region, when compared with the low BMD group (t score <-1). SOS was negatively correlated with age (r=-0.66) and month since menopause (r=-0.57). The sensitivity, specificity, and positive and negative predictive values for QUS t score to diagnose low BMD did not seem to be satisfactory at either of the measurement sites. CONCLUSION: Tibial SOS was correlated weakly with BMD values of femur and lumbar spine as measured by DEXA and its diagnostic value did not seem to be high for discriminating between normal and low BMD, at these sites.

MRI characteristics and transverse relaxation time measurements in normal growing cartilage / 华中科技大学学报（医学）（英德文版）

To determine the characteristics of magnetic resonance (MR) signals of normal growing cartilage and identify the difference in transverse relaxation times between physeal and epiphyseal cartilage in vivo. 24 distal femora of 12 two-week-old piglets were imaged on a 1.5 Tesla GE MR scanner. Comparison was made between signal intensity on MR images and the structure shown in corresponding histologic sections. T2 values were measured in eight piglets by means of multiecho spin-echo sequences. Our results showed that MR imaging delineated five regions between the secondary ossification center and the metaphysis, which histologically correspond to the zone of provisional calcification of the secondary ossification center, physis of the secondary ossification center, epiphyseal cartilage, physis and zone of provisional calcification. The T2 value in the physeal cartilage was much larger than that in the epiphyseal cartilage (P<0.05). It is concluded that MRI findings could differentiate the different regions of growing cartilage. T2 is longer in physeal than in epiphyseal cartilage, perhaps reflecting differences in water binding by proteoglycans.

Efecto del nivel de calcio de la dieta consumida durante gestación y lactancia sobre el zinc en sangre y hueso, en ratas / Effect of dietary calcium during pregnancy and lactation on zinc levels in blood and bone, in rats

The effect of dietary calcium (Ca) level on maternal zinc (Zn) nutritional status was studied. Female Wistar rats, weighing 250-350 g, were fed during pregnancy and lactation with an experimental diet containing/100 g different levels of calcium: 0.2 g (low calcium: LCa), 0.6 g (normal calcium: NCa) or 0.9 (high calcium: HCa). Maternal blood samples were drawn from the tail at delivery and at the end of lactation. Laboratory determinations were: Zn in whole blood (WB) at delivery and weaning; Zn (ZnF) and Ca (CaF) in the ashed femur at weaning. The results (mean +/- SEM) were: ZnWB (microgram/ml) at delivery and weaning: LCa: 8.73 +/- 1.05; 12.8 +/- 2.02; NCa: 3.49 +/- 0.19; 3.73 +/- 0.37; HCa: 3.21 +/- 0.19; 3.85 +/- 0.27. CaF (mg/100 mg): LCa: 19.2 +/- 0.8; NCa: 21.4 +/- 0.6; HCa: 20.4 +/- 1.1. ZnF (microgram/100 mg): LCa: 30.2 +/- 0.9; NCa: 24.1 +/- 0.3; HCa: 24.1 +/- 0.9. ZnWB was significantly higher in LCa (p < 0.0001) regarding NCa and Hca. ZnF showed an increase and CaF a decrease in LCa regarding NCa and HCa (p < 0.0001). There were no significant differences in ZnWB, ZnF and CaF between NCa and HCa These results show that: there was no detrimental effect when dietary Ca content was increased by 50 per cent above the normal requirements of the rat.; low dietary Ca during pregnancy and lactation produced an increase of Zn utilization, reflected in maternal blood Zn and in ZnF content.

Variaciones en el contenido de calcio, fosfato, magnesio y sodio en huesos de ratas macho castradas / Variations in the contents of calcium, phosphate, magnesium and sodium in bones of castrated male rats

Un grupo de ratas macho Holtzman de tres meses de edad fue bilateralmente castrado (TX). Otro grupo igual (control) fue sometido a operación simulada. La alimentación fue ad libitum para el grupo control y restringida para el TX. A los 30,60, 90, 120 y 150 días de la castración se seccionó un segmento de cola a todas las ratas. A los 150 días de realizó densitometría mineral ósea (BMD) a todos los animales, se sacrificaron y se extrajeron los fémures izquierdos. En los huesos de la cola (HC) y en los fémures se determinaron las cenizas y las concentraciones de Ca++, PO4(-3), Mg++ y Na+. En los HC, a los 30 días disminuyeron las cenizas y la concentración de Ca++, PO4(-3), (p<0,05) en las ratas TX. A los 60 días las cenizas y todos los iones analizados habían disminuido (p<0,05 y p<0,025) en las ratas TX, descenso que se profundizó más adelante. Las disminuciones más significativas en los HC se observaron para el Ca++ a los 90 días (p<0,005); para las cenizas a los 120 días (p<0,005); para el fosfato, el Mg++ y el Na+ a los 150 días (p<0,005). A los 150 días las cenizas y las concentraciones de los iones analizados no mostraron diferencias estadísiticamente entre los HC y los fémures. La BMD a los 150 días disminuyó en el grupo TX (p<0,05). No hubo diferencias estadísticas entre los pesos corporales de los dos grupos de ratas durante toda la experiencia. Los resultados sugieren que en ratas macho castradas a los tres meses de edad, los contenidos de calcio, fosfato, magnesio y sodio y las cenizas en HC son buenos indicadores de la pérdida de masa ósea, a partir de los 30 y 60 días de la castración. Además, a los 150 días la desmineralización ósea se refleja cuantitativamente igual en fémur que en HC, y el descenso en la concentración de los iones óseos sería mejor indicador de pérdida de masa ósea que la disminución de BMD.

El olpadronato previene la perdida de hueso cortical y trabecular inducida por dosis suprafisiologicas de tiroxina en ratas ovariectomizadas / Olpadronate prevents cortical and trabecular bone loss induced by supraphysiological dosis of thyroxine in ovariectomized rats

En el presente estudio experimental en ratas se evaluaron los efectos de la ovariectomia (OVX) y la administración de tiroxina (T4) sobre la densidad mineral ósea (DMO) del hueso cortical y trabecular. Además se estudió la eficacia del olpadronato (Olpa) para prevenir la pérdida ósea axial y periférica inducida por el exceso e hormonas tiroideas. Ratas hembras Sprague-Dawley (220 + 2 gr)se dividieron en los siguientes grupos: SHAM, OVX+Vh (Vh: vehículo); OVX+T4 (T4 250 mug/Kg peso/día); OVX+Olpa (0.3 mg de Olpa/Kg de peso/semana) y OVX+T4+Olpa (ambos: T4+Olpa). La DMO de las OVX+Vh fue significativamente menor que la de las SHAM en tibia total (p<0.01) pero no en el fémur ni en la columna lumbar. En el segmento medio de la tibia los resultados fueron similares en ambos grupos; un valor menor se observó en la parte distal (pns) y en la proximal (p <0.003) en el grupo OVX+Vh. La DMO de las OVX+T4 fue significativamente menor que la de las OVX+Vh en la tibia total (p<0.02), el fémur (p<0.006), la columna lumbar (p<0.006); además, la DMO de las OVX+T4 fue menor en todos los sectores analizados de la tibia, pero alcanzó un nivel estadísticamente significativo sólo en la parte media (p<0.004). La DMO de las OVX+Olpa fue mayor que la de las OVX+Vh en fémur (p<0.002), columna lumbar (p<0.03), tibia total (p<0.001) y tibia proximal (p<0.001). Sorprendentemente, la DMO de las OVX+Olpa fue mayor que la de las SHAM, en tibia total y proximal (p<0.05 y p<0.001, respectivamente). La DMO del grupo OVX+T4+Olpa fue significativamente mayor que el de OVX+T4 en fémur (p<0.001), columna lumbar (p<0.001), tibia total (p<0.001), tibia proximal (p<0.0001); asimismo, alcanzó niveles significativamente mayores que la de las SHAM en columna lumbar, tibia total y proximal (p<0.01 para todas ellas). El presente estudio sugiere que el hueso cortical, en condiciones de deficiencia estrogénica, sería más sensible que el trabecular al efecto de la T4. El Olpa prevendría la pérdida ósea axial y periférica del hueso inducida por un exceso de hormonas tiroideas.

Effect of total food deprivation on the proteoglycans of rat hyaline cartilage and bone

Hay hipótesis que sugieren que el efecto de la privación total de alimentos sobre el hueso ocurre por alteraciones en la síntesis de la matriz orgánica. Este trabajo se llevó a cabo con el propósito de caracterizar las posibles alteraciones en las propiedades de los proteoglucanos de cartílago hialino y hueso de rata como resultado de un ayuno total. Ratas macho de la cepa Wistar fueron separadas aleatoriamente y asignadas a un grupo control que comió y bebió "ad libitum" o a un grupo experimental que únicamente bebió agua. Los animales fueron pesados y sacrificados a los 4 u 8 días de iniciada la experiencia después de administrarles una dosis de 35S(-SO4-). Se aislaron los PG de los fémures y cartílagos xifoides y se determinó la captación de 35S, el patrón de distribución de los GAG, el peso molecular y densidad de los PG y el largo de las cadenas laterales. Todos los parámetros analizados disminuyeron significativamente después de 4 y 8 días mostró una disminución de la fracción correspondiente al Congroitin-4-Sulfato. Estos resultados podrían indicar una alteración en el proceso de osificación como consecuencia de las modificaciones en las propiedades de los PG que alterarían su unión con el colágeno, molécula que desempeña un papel muy importante en el mencionado proceso