Dietary lipids, prostaglandin E2 levels, and tooth movement in alveolar bone of rats

Abstract

A previous study showed that certain dietary lipids can alter arachidonic acid concentrations in alveolar bone. Because arachidonic acid is a precursor of prostaglandin (PG) E2, which is known to play an important role in orthodontic tooth movement, the purpose of the present study was to determine the effect of dietary lipids on PGE2 levels and tooth movement. Two groups of male Sprague-Dawley rats (20/group) were fed nutritionally adequate purified diets containing 10% corn oil (group I, rich in n-6 fatty acids) or 9% ethyl ester concentrate of n-3 fatty acids + 1% corn oil (group II rich in n-3 fatty acids). After 5 weeks of feeding the diets, orthodontic force of 56 g was applied to the maxillary incisors to tip them distally. Prior to killing the rats at day 4 and 8 of orthodontic force application, tooth movement was measured by computerized image analysis. Premaxillae were dissected out free of soft tissue and incisors. The alveolar bone was frozen in liquid nitrogen, pulverized, and lipids were extracted. The concentrations of arachidonic acid and fatty acid composition of total phospholipids were measured by gas chromatography. PGE2 levels were measured by enzyme immunoassay. Arachidonic acid and PGE2 concentration were significantly lower (P < 0.001) in alveolar bone of rats in group II than in group I. The tooth movement was also significantly lower (P < 0.02) in group II than in group I at both 4 and 8 days. The results suggest that PGE2 levels in alveolar bone and orthodontic tooth movement can be affected by the type of dietary fat.

Review of Nonprimate, Large Animal Models for Osteoporosis Research

“…Turner (12) has previously speculated that sensitivity to an estrogen deficiency in an ovariectomized animal model may be increased in relation to the frequency of estrous cycles. Consistent with the comparatively shorter estrous cycles and gestation periods, the bone remodeling cycle is generally shorter in smaller animals (e.g., mice and rats (13) < rabbits (14) < dogs (15) < humans (16) ) than in larger species of mammals. Overall, some sort of systematic contrast of estradiol status may be warranted to establish whether there is reasonable similarity in terms of cause and effect when it comes to estradiol diminution and bone loss in nonhuman mammals.…”

“…Despite the increase in osteoblast number and boneforming cells, this finding was attributed to a decrease in osteoblastic function that had ramifications at the tissue level. Dannucci et al (27) observed increased osteocalcin levels in dogs after OHX (weeks [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], indicating an increased rate of bone turnover similar to what transpire in postmenopausal women with high remodeling osteoporosis. Decremental changes for bone histomorphometric values (BV/TV and Tb.Th) of the iliac crest and for serum biochemical parameters have also been shown by Fukuda and Ilda (54) in 2-yr-old male beagles examined before and 12 mo after orchidectomy.…”

Orthodontic mechanotransduction and the role of the P2X7 receptor

“…In bone biology, lower dosages of PGE2 were shown to have anabolic effects, whereas higher dosages appear to disrupt this effect and cause bone resorptionthis effect appears to be linked to a consequential increase in IGF-1 levels (Baylink, Finkelman & Mohan, 1993). In orthodontics, there seems to be a consensus on the fact that PGE2 injections increase the rate of tooth movement (Bao, Zhao & Rao, 1995;Chao et al, 1988;Kale et al, 2004;Kokkinos et al, 1993;Leiker et al, 1995;Seifi, Eslami & Saffar, 2003). In contrast to orthopedic studies, which typically show anabolic effects of PGE2 (Norrdin, Jee & High, 1990), studies have reported increase in bone resorption alone (Boekenoogen et al, 1996;Chao et al, 1988;Kale et al, 2004;Leiker et al, 1995;Seifi et al, 2003;Yamasaki, Shibata & Fukuhara, 1982).…”

Albumin‐bound lipids induce free cytoplasmic calcium oscillations in human osteoblast‐like cells

“…Other studies have shown similar ½Ca 2þ i oscillations and increased proliferation in astrocytes exposed to albumin-bound lipids. 2,3 The influence of lipids on bone and osteoblasts has been studied with respect to bone density, 4 prostaglandin formation 5 and bone IGF-I levels, 6 but not regarding the influence on ½Ca 2þ i . By serendipity we have found that the ½Ca 2þ i oscillations that we previously demonstrated, are induced by lipids bound to albumin.…”