L-Dopa Potentiates Presynaptic Inhibitory α2-Adrenoceptor- but Not Facilitatory Angiotensin II Receptor-Mediated Modulation of Noradrenaline Release from Rat Hypothalamic Slices

Abstract
The effects of menatetrenone, a vitamin K2 homologue, on bone loss induced by ovariectomy in rats were studied in 3 experiments. Menatetrenone was given as a dietary supplement. In experiment 1, at 2 weeks postovariectomy, menatetrenone (10 mg/kg/day given for 2 weeks) inhibited the decrease in bone density of the femoral metaphysis induced by the ovariectomy. In experiment 2, menatetrenone (3 or 30 mg/kg/day given for 6 months) inhibited the decrease in bone strength of the femur and the decrease in calcium and hydroxyproline content of the femoral diaphysis at 6 months postovariectomy. In experiment 3, menatetrenone treatment, at 30 or 100 mg/kg/day for 6 months, protected against the decrease in bone strength and calcium and hydroxyproline content in the bone loss model induced by ovariectomy and calcium-deficient diet. These findings suggest that menatetrenone protects against the bone loss induced by ovariectomy.

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