The present study was designed to evaluate the effect of olive oil and its main polyphenol (oleuropein) in ovariectomised rats with or without inflammation. Rats (6 months old) were ovariectomised or sham-operated as control. Ovariectomised rats were separated into three groups receiving different diets for 3 months: a control diet with 25 g peanut oil and 25 g rapeseed oil/kg (OVX), the control diet with 50 g olive oil/kg or the control diet with 0·15 g oleuropein/kg. The sham-operated group was given the same control diet as OVX. Inflammation was induced 3 weeks before the end of the experiment by subcutaneous injections of talc (magnesium silicate) in one-half of each group. The sucess of ovariectomy was verified at necropsy by the atrophy of uterine horns. Inflammation, oleuropein or olive oil intakes did not have any uterotrophic activity, as they had had no effect on uterus weight. The plasma concentration of a-1-acid glycoprotein (an indicator of inflammation) was increased in OVX rats with inflammation. With regard to bone variables, osteopenia in OVX was exacerbated by inflammation, as shown by a decrease in metaphyseal and total femoral mineral density. Both oleuropein and olive oil prevented this bone loss in OVX rats with inflammation. At necropsy, oleuropein and olive oil consumption had had no effect on plasma osteocalcin concentrations (marker of bone formation) or on urinary deoxypyridinoline excretion (marker of bone resorption). In conclusion, oleuropein and olive-oil feeding can prevent inflammation-induced osteopenia in OVX rats.

This exploratory study supports preclinical observations and warrants further research by showing that a specific olive polyphenol extract (Bonolive®) affects serum osteocalcin levels and may stabilize lumbar spine BMD. Moreover, the improved blood lipid profiles suggest additional health benefits associated to the intake of the olive polyphenol extract.

Fifty Holstein dairy cows (26 primiparous) were used to evaluate effects of level of concentrate and of slow release recombinant bST on plasma hormones and metabolites. Blood was sampled at wk 14 and 20 of lactation, which was 5 and 11 wk after the first bST injection. In addition, at d 3 and 10 after the third bST injection, diurnal profiles of somatotropin and metabolites were studied in 7 bST cows and 5 control cows by blood sampling every 20 min over 6 h. Supplementation by bST enhanced plasma somatotropin and insulin-like growth factor-I but did not significantly affect plasma concentrations of triiodothyronin and insulin. The bST supplementation increased plasma NEFA at wk 14 and reduced uremia at wk 20. Primiparous cows showed higher plasma NEFA and triiodothyronin than multiparous cows at both sampling periods, higher insulin-like growth factor I, and lower beta-hydroxybutyrate at wk 14, and higher glucose and lower insulin at wk 20. In the diurnal kinetic study, bST supplementation did not alter bST spike frequency and duration but increased spike magnitude, the area under the curve above the baseline, and the baseline mean. Sixty-one to 56% of the increase over controls in plasma bST total area was due to increase in the area under the curve above baseline. Preprandial NEFA were increased by bST at d 10.

Studies about bone formation and regulation are complex due to a close relationship between bone cells. Primary cell cultures allow to understand osteoblastic function. We isolated cells from the cortical metacarpal bone of 85 or 120 day-old ovine fetuses by an enzymatic method. After first passage and cell amplification, the growth medium (DMEM, ascorbic acid and fetal calf serum 10%) was replaced at confluence by a mineralization medium (MM: DMEM, ascorbic acid, beta-glycerophosphate, insulin). Alkaline phosphatase (ALP) activity in cell-matrix layer increased after 4 days of cultures in MM and maximized at day 6. We also measured osteocalcin, ALP and IGF-I secretion simultaneously during mineralization. PTH, PTHrP and 1.25(OH)2D3 decreased ALP activity in cell-matrix layer after 4 days of treatment in MM without fetal calf serum (FCS). Cells from 120 day-old fetuses were cultivated in MM with 10% FCS during 32 days to induce mineralization. Inorganic phosphorus concentration increased in medium between days 5 and 12, Ca concentration decreased in medium after 12 days of culture. Mineralization started at day 12, in the same time ALP activity appeared in medium. Osteocalcin secretion increased between days 6 and 12, decreased at day 14 and increased from day 16 until day 32. Ovine fetal bone cells produced IGF-I until first days of culture in MM. Such ovine osteoblast phenotype cells having the capacity to differentiate and mineralize in vitro would be a model to study the endocrine regulation of osteoblastic function in large mammals.