Effect of ovariectomy on intraosseous vascularization and bone remodelling in rats: action of tiludronate.

In order to study the action of tiludronate on the changes in intraosseous vascularization induced by ovariectomy, and to link these effects to those observed in bone remodelling, 30 female Sprague-Dawley rats (age 40 weeks) were studied. Ten rats were shamoperated and treated by vehicle, 10 rats were ovariectomized and treated by vehicle, and 10 rats were ovariectomized and treated orally with tiludronate, 0.16 mmol/kg/per day, 3 days a week for 16 weeks, from the day following ovariectomy. The rats were killed after 4 months, and a histomorphometric study and quantification of intraosseous vessels carried out on the sixth lumbar vertebra. The area of the intraosseous sinusoidal capillaries increased after ovariectomy, which also induced a moderate increase in resorption surfaces and osteoid surfaces leading to a decrease of 40% in the trabecular bone volume at the lumbar spine level. This bone mineral loss was completely prevented by tiludronate, which normalized the bone turnover. However, tiludronate was without any effect on intraosseous vascularization. These results indicate that the surface area of the intraosseous sinusoidal capillaries was correlated positively with resorption surfaces and negatively with trabecular bone volume and the number of bone trabeculae. In these experimental conditions, an inhibitor of bone resorption can exert its positive effect on bone mass without normalization of vascularization.

Magnesium-deficient hairless rat: spleen cells mitogenic responses and variations in hormonal status.

Hairless rats with dermatosis induced with a poor magnesium diet were previously shown to bear biochemical and immunological abnormalities. It was therefore felt of interest to investigate the spleen cells proliferative responses from these rats, both in the rash and the remission phases, when testosterone and parathormone plasma levels were also determined. Results showed that proliferative responses to mitogens and PTH levels were inversely related to the intensity of the dermatosis, whereas testosterone levels were more or less decreased. The role of 1.25 dihydroxyvitamin D3 in these modifications is questionable.

Dermatosis in magnesium-deficient hairless rats: effects of steroidal and non-steroidal anti-inflammatory drugs.

Dermatosis in magnesium-deficient hairless rats has been described as a reproducible model of skin inflammation. It was therefore felt of interest to search for the effects of various anti-inflammatory compounds on this model. Results showed that 1) Dexamethasone acetate completely abolished the rash, 2) Indomethacin, a Non-Steroidal Anti-Inflammatory Drug (NSAID), inhibitor of the cyclooxygenase pathway was quite inactive, 3) Benoxaprofen, a NSAID inhibitor of both cyclooxygenase and lipoxygenase pathways only slightly modified the development of the pathology. Activity of steroidal anti-inflammatory drugs on this model may be related to their immunosuppressive effects.