estradiol-3-benzoate and Magnesium-Deficiency

Magnesium-deficient rats develop simultaneously a significant lowering of nociceptive threshold and a generalized inflammation. We investigated the relationship between these two phenomena by testing drugs that are able to suppress the inflammation in this model. In weaning rats fed a magnesium-depleted diet for ten days, the nociceptive threshold was assessed by the paw pressure test and the inflammation by a clinical score. A non-steroidal anti-inflammatory drug (piroxicam); antagonists of H1 and H2 receptors (astemizole and cimetidine. respectively); a glucocorticoid (dexamethasone); an inhibitor of mastocyte degranulation (cromoglycate); and estradiol benzoate were used to block the inflammatory response. Dexamethasone and estradiol significantly suppressed the inflammation (p < 0.001 vs control group). Cromoglycate showed a delayed anti-inflammatory effect (p < 0.01 vs control group on D10). The combination of astemizole and cimetidine partially blocked the inflammation process, whereas astemizole and piroxicam were without effect. Regardless of the effect of the test drugs on inflammation, no change in the time course of hyperalgesia was observed. These data support the view that hyperalgesia induced by the magnesium-depleted diet is not a consequence of the inflammatory process.

Topics: Animals; Anti-Inflammatory Agents; Astemizole; Cimetidine; Cromolyn Sodium; Dexamethasone; Disease Models, Animal; Estradiol; Hyperalgesia; Inflammation; Magnesium Deficiency; Male; Piroxicam; Rats; Rats, Wistar

To investigate interactions between circulating sex hormones, dietary fructose and magnesium on bone mineral density and numbers of trabeculae, 10 weeks old orchiectomized and sham-orchiectomized rats were studied. One-third of the orchiectomized animals were injected with beta-oestradiol-3-benzoate twice per week in sesame oil; another one-third, testosterone cypionate; the remaining one-third as well as the sham-orchiectomized animals, sesame oil only. All animals were fed either fructose or cornstarch without added magnesium. After 14 weeks, a 24 h urine sample was collected for measurements of calcium, magnesium, phosphorus, and cAMP. Blood was collected for determinations of calcium, magnesium, phosphorus, 25-monohydroxy and 1,25-dihydroxycholecalciferols, oestrogen, testosterone, and parathyroid hormone. Femurs were used for measurements of bone mineral density, and tibiae, for numbers of trabeculae. Exogenous testosterone interacted with starch and magnesium deficiency to decrease serum calcium concentration significantly, which increased circulating parathyroid hormone. High circulating parathyroid hormone raised urinary cAMP and serum 1,25-dihydroxycholecalciferol. Increased parathyroid hormone, cAMP and 1,25-dihydroxycholecalciferol may be responsible for bone resorption which was noted in reductions of bone mineral density and the numbers of trabeculae in the group. In contrast, exogenous oestrogen interacted with fructose and magnesium deficiency to increase serum calcium concentration which caused a reduction of circulating parathyroid. Low parathyroid hormone, reduced 1,25-dihydroxycholecalciferol and cAMP may explain the increased bone mineral density and the numbers of trabeculae in this group.

Topics: Animals; Body Weight; Bone Density; Bone Diseases, Metabolic; Calcifediol; Calcitriol; Calcium; Cyclic AMP; Estradiol; Fructose; Magnesium; Magnesium Deficiency; Male; Orchiectomy; Parathyroid Hormone; Phosphorus; Rats; Starch; Testosterone

To investigate interactions between circulating oestrogen, high dietary fructose, and low dietary magnesium on bone mineral density and numbers of trabeculae, 10 week old ovariectomized (OVX) and sham-ovariectomized (SOVX) rats were studied. The OVX animals were divided into three groups: one-third of the animals were injected with beta-oestradiol-3-benzoate dissolved in sesame oil twice a week; another one-third were injected with testosterone cypionate; and the remaining OVX and all of the SOVX animals were injected with sesame oil only. One-half of the animals in each group were fed cornstarch without magnesium and the other half, fructose without magnesium. After a 14 week experimental period, a 24 h urine sample was collected for measurements of Ca, Mg, P and cAMP. Blood was collected for determination of Ca, Mg, P, 25-hydroxy- and 1,25-dihydroxy-cholecalciferol. Femurs were used for determination of bone density, and tibiae for numbers of trabeculae. Testosterone-treated and OVX control animals fed cornstarch diets had the lowest bone density, whereas oestrogen-treated and SOVX control rats fed fructose had the greatest bone density. Oestrogen-treated animals fed fructose without magnesium had the highest serum and urinary Ca, whereas testosterone-treated animals fed cornstarch without magnesium had the lowest serum and urinary Ca. Serum alkaline phosphatase was higher in OVX- and testosterone-treated and starch-fed animals as compared to their respective counterparts. High urinary cAMP in OVX- and testosterone-treated animals may reflect the action of increased circulating concentrations of PTH, which could be responsible for bone resorption. The results show that high dietary fructose without magnesium interacts with endogenous or exogenous oestrogen to decrease bone mineral loss significantly in ovariectomized rats.

Topics: Animals; Bone and Bones; Calcifediol; Calcitriol; Calcium; Cyclic AMP; Estradiol; Female; Fructose; Magnesium; Magnesium Deficiency; Ovariectomy; Phosphorus; Rats; Rats, Sprague-Dawley; Testosterone