Age-related changes in hematological values, serum biochemical constituents, and weights of various organs in both sexes of the Spontaneously Hypertensive (SHR/Izm), Stroke-prone SHR (SHRSP/Izm), and Wistar Kyoto (WKY/Izm) rat strains, bred under SPF conditions, were examined to obtain fundamental data. The body weights from 3-30 weeks and systolic blood pressure from 6-30 weeks in each strain were measured every week. At the ages of 8, 16, and 30 weeks, the hematological values (erythrocyte, hemoglobin, hematocrit, leucocyte, thrombocyte), serum biochemical constituents (total protein, GOT, GPT, ALP, BUN, creatinine, glucose, total Ca and phosphorus, and ionized Ca, Na, K, and Cl were measured. Also, the organs, brain, heart, lung, thymus, liver, spleen, pancreas, bilateral kidneys, adrenal glands, testes/ovaries, digestive tract, and muscle (soleus) were weighed. The age-related changes as well as the strain and sex differences in each measured item were examined. The body weights of each strain increased, but rate of the increase was less in SHR and SHRSP, and was lowest in SHRSP. The blood pressure of SHR and SHRSP elevated with age, and showed higher in SHRSP than SHR, while that of WKY did not change. There were many strain differences in most measured items at each time point, particularly at 30 weeks. In SHRSP, high values of BUN, creatinine, total and ionized Ca, weights of brain, heart, liver, kidney and digestive duct were observed at most time points indicating that this strain's abnormality of calcium metabolism may be related to functions of the kidney and digestive duct as well as hypertension.

ABSTRACT. Age-related changes in bone mineral density (BMD), cross-sectional area and strength strain index (SSI) of the long bones in the limbs and first lumbar vertebra of male Wistar rats were measured by a peripheral quantitative computed tomography (pQCT) method. One hundred and ten rats aged 2-30 months were used. The results indicate that the total (cortical + trabecular), cortical and trabecular BMD values of the metaphysis and cortical BMD values of the diaphysis in the long bones varied for each bone and differed from those of the first lumbar vertebra. The total BMD of long bones showed high values at 6-21 months and then decreased, but these did not always coincide with cortical and trabecular BMD. The values of SSI in the long bones varied. The values of total and cortical BMD and SSI of lumbar vertebra increased for 6-12 months and then decreased, but the trabecular BMD increased after 12 months. The total area in both the long bones and the first lumbar vertebra increased with the decrease in cortical area and the increase in the trabecular area with increasing age. It was concluded that age-related changes in bones, similar to those observed in humans, could be observed in some bones and parameters, although the age in rats when the so-called peak bone mass appears in the whole skeleton could not be clearly determined. KEY WORDS: age change, bone mineral density, male rat, peak bone mass, peripheral quantitative computed tomography (pQCT) J. Vet. Med. Sci. 64(1): 29-34, 2002 Rats are widely used for studies on bone metabolism and diseases such as osteoporosis, although their worth as an animal model has been contested [6,12,16,21] because their bone morphological patterns differ from those of humans. Rats show a modeling pattern from youth to old age, while humans show a modeling pattern in the growth stage which changes to a remodeling pattern after maturity [7]. The length and weight of long bones in rats continue to increase up to the old age due to the fact that both or either of the epiphysial growth plates do not close for a long time [8]. The cortical and trabecular bone components of the femur neck in rats have been found to be higher and lower, respectively, than those in humans [3].The age of peak bone mass, hereafter referred to as bone mineral density, in a human is considered a significant indicator for knowing the state of activity of bone metabolism and age of onset of osteoporosis, because thereafter the bone mass reduces with increasing age. To clarify whether rats show peak bone mass or not is an important matter for considering their worth as a model animal in bone researches and for determining corresponding ages between rats and humans in experimental procedures and assessing experimental results. That is, we are interested to know if rats have age-related changes in bone metabolism throughout their life similar to those in humans. We demonstrated that high values of mineral and organic contents at various skeletal sites are present in rats [11] and a peak of bone volume i...

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The aim of the present study was to examine the effect of different frequencies of running exercise on increasing bone mineral density (BMD) and improving bone histomorphology at various sites of the skeleton (tibia, femur, and second lumbar vertebra) in young rats. Twenty-five female Wistar rats, 8 weeks old, were divided into five groups, of 5 animals each according to running load: control group, no running (A group); running load (RL), 4 days per week (d/w; B group); RL, 5 d/w (C group); RL, 6 d/w (D group); and RL, 7 d/w (E group). Rats ran on a treadmill at a speed of 15 m/min for 30 min per day over an 8-week period. The results indicated that the BMD of the tibia in the B, C, D, and E groups and that of the femur in the B and E groups increased significantly over that of the A group. However, the cortical BMD and trabecular BMD of the second lumbar vertebra did not change. In regard to bone histomorphometry of the tibia, a parameter of bone resorption (eroded surface/bone surface) was significantly lower in the B and D groups than in the A group. There were no differences in the parameters of bone formation. Tartaric acid-resistant acid phosphatase (TRACP) values were significantly lower in the B and C groups than in the A group. There were significant increases in body weight in the B group and in muscle weight in the C group. From the data obtained in this study, it was concluded that increases in BMD were obtained by a moderate running load at frequencies of 4 and 5 days per week.

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ABSTRACT. The effects of orchidectomy on bone metabolism in male beagle dogs were examined using twelve 2-year-old dogs that were orchidectomized. The dogs' bilateral iliac bones, double-labeled with tetracycline and calcein for the histomorphometry, were obtained from three dogs prior to orchidectomy and at 3, 6, 9, and 12 months afterwards. The serum biochemical constituents related to bone metabolism were examined before and every month after orchidectomy. Between 1 and 6 months after orchidectomy, the value of serum testosterone decreased (1 month), while the levels of parathyroid hormone, calcitonin, total calcium, osteocalcin, and alkaline phosphatase activity increased significantly, indicating a high bone turnover. The mean trabecular thickness and the fraction of labeled osteoid surface decreased significantly 3 months after orchidectomy, but other histomorphometric parameters were unchanged. In the period 7-12 months after orchidectomy, the parathyroid hormone level increased ever and above that of the first 6-month period, while the levels of calcitonin, osteocalcin, alkaline phosphatase activity, and phosphorus decreased. The bone volume, mean trabecular thickness, and the fraction of labeled trabecular surface decreased significantly compared with the pre-orchidectomy values. These findings indicate an imbalance in bone metabolism ( i.e. bone resorption > bone formation). These results indicate that a loss of bone volume accompanied the fall in sex hormone levels following orchidectomy and suggest that the orchidectomized dog is available as an animal model for studying osteoporosis caused by hypogonadism and the decline of sex functions in men.-KEY WORDS: bone histomorphometry, canine, iliac bone, orchidectomy.

ABSTRACT. Age-related changes in bone mineral density (BMD) and cross-sectional area and bone strength index (SSI) of the femur, tibia, humerus, and first lumbar vertebra in female Wistar (WM/MsNrs) rats were examined by a quantitative computed tomography (pQCT) method. One hundred and sixteen virgin female Wistar (WM/MsNrs) rats aged 2-33 months were used. The data indicate that the to tal BMD values of metaphyses and diaphyses of long bones increased until 12 months, then decreased to a varying degree depending on the bone after 15-24 months, but the values of cortical and trabecular BMD with age were not always similar to the total BMD value. Nevetheless, the values for cross-sectional area and SSI in the long bones increased regardless of the total BMD decrease with a ge, indicating that this increase might have been due to a characteristic of the modeling pattern in rats. The total and cortical BMD values in the first lumbar vertebra decreased after 18 months, and SSI did after 15 months. The data obtained in this study were compared with those obtained from males in a previous study. In conclusion, it was indicated that in this strain the rats over 12 months with the highest total BMD values in the femur and tibia, and before the onset of various tumors, are useful as a model animal for osteoporosis experiments and observation of senile bone change. KEY WORDS: bone mineral density, cross-sectional area, female Wistar rat (WM/MsNrs), pQCT, strength strain index.J. Vet. Med. Sci. 66 (7): [755][756][757][758][759][760] 2004 We have previously reported the age-related changes in bone mineral density (BMD), cross-sectional area, and strength strain index (SSI), an indicator of bone fragility, in male rats [17], as rats are widely used for experiments regarding bone disease and for pharmacological tests. Female rats are more frequently used than males, for example, as a model of postmenopausal osteoporosis after ovariectomy treatment. Nevertheless, the differences between rats and humans in bone metabolic and morphologic characteristics have been contested [2,7,8,18,25,34]. Furthermore, although many studies on bones in the rat have carried out, the data have varied because of differences in the bones observed and the measurement methods [3,9,11,13,16,22,27,32,33].We consider it important to clarify the age-related changes in bones throughout the life span of rats to determine whether it is worthwhile to use rats in studies related to bones. Our report regarding the life span and incidence of tumors in this strain is available to aid in our understanding of the changes in bones with age in rats as laboratory animals [10].The measurement of BMD, cross-sectional area, and SSI in the present study was done by the QCT method because this method has merits with regard to simultaneously measuring BMD and morphologic features by separating trabecular and cortical bones, and because it can be carried out in live rats, the same as in clinical use for humans, as described previously [17].The purpose of the present stud...

A series of experiments was carried out with the antimycotic agent clotrimazole to establish MICs against a number of different yeasts and to estimate its blood levels following oral administration. Marked differences were noted between the MIC against A and B serotypes of Candida albicans in its yeast-like cell form, that against Type B being nearly 10-times higher than against Type A. Against the mycelial form, however, the MIC was much lower and there was little difference between the levels for the two serotypes. Clotrimazole administered in oral tablet form appeared to be poorly absorbed, little being transferred to the blood. Urinary levels were low and large amounts of the drug were detected in the faeces. Serum levels were below MIC levels in all cases examined. Blood levels 3-times as great as those after the same dosage in tablet form were produced when clotrimazole was given in oil solution and even with 250 mg, effective blood levels were achieved and maintained.