Tetracycline administration normalizes the structure and acid phosphatase activity of osteoclasts in streptozotocin‐induced diabetic rats

Abstract

Diabetes induces osteopenia, which is characterized by a deficiency of osteoid and decreased activity of osteoblasts. We recently found that tetracyclines prevent the loss of osteoid and bone matrix and the degeneration of osteoblasts in diabetic rats by a mechanism independent of their antimicrobial efficacy. However, bone remodeling requires the activity of osteoclasts as well as osteoblasts. To determine the in vivo effects of tetracycline on osteoclasts in long bones, either a tetracycline (minocycline, TC) or its chemically modified non-antibiotic analogue (CMT), 4-de-dimethylaminotetracycline, was administrated daily to streptozotocin-induced diabetic rats by oral intubation. After 21 days, the rats were perfusion-fixed with a mixture of formaldehyde and glutaraldehyde, and the humeri were dissected and processed for ultracytochemical demonstration of acid trimetaphosphatase (ACPase) activity. In untreated non-diabetic (control) rats, the osteoclasts at the zone of provisional ossification exhibited abundant mitochondria and cisterns of rough endoplasmic reticulum (RER) throughout the cytoplasm, prominent stacks of Golgi membranes, and lysosomes in the perinuclear cytoplasm, and numerous various pale vacuoles in the cytoplasmic area adjacent to well-developed ruffled border. Intense ACPase activity was observed in the Golgi saccules, lysosomes, pale vacuoles, and the extracellular canals of ruffled border. The reaction products were also noted along the resorbing bone surfaces associated with the osteoclast ruffled border. The osteoclasts in the untreated diabetic rats showed a cytoplasmic organization similar to that of the non-diabetic control rats, but showed little or no ruffled border which was replaced by a broad clear zone in some of these cells. However, most of the osteoclasts on bone matrix in the diabetics were devoid of both a ruffled border and a clear zone. ACPase activity was detected in the osteoclast cytoplasm of diabetic rat, as in the controls, but to a much lesser extent along the broad clear zone facing the resorbing bone surfaces. The osteoclasts in TC-treated diabetic rats possessed both a clear zone and a small ruffled border. However, in some cases, they lacked both structures reminiscent of the untreated diabetic cells. The osteoclasts of CMT-treated diabetic rats exhibited structural and enzymatic features essentially identical to those of the non-diabetic control rats. These results suggest that the diabetes-induced osteopenia results, at least in part, from degeneration of osteoclasts (as well as atrophic osteoblasts) and that tetracyclines may be effective in preventing these abnormalities by a mechanism not dependent on the drugs' antimicrobial properties.

Tetracycline administration restores osteoblast structure and function during experimental diabetes

“…This osteoclast abnormality in diabetes may result from a prior inactivation of the osteoblasts and decreased release of soluble cytokine(s) by these cells required for osteoclast differentiation (Heath et al, 1985;McSheehy and Chambers, 1986a,b;Thomson et al, 1986). These results are consistent with earlier reports that diabetes-induced bone loss (osteopenia) results from impaired bone formation rather than increased osteoclastic bone resorption (Hough et al, 1981;Shires et al, 1981;Golub et al, 1990;Kaneko et al, 1990).…”

Effect of tetracyclines which have metalloproteinase inhibitory capacity on basal and heparin-stimulated bone resorption by chick osteoclasts

“…Dox reverses osteopenia in diabetic rats I-5]. CMT also (i) inhibits in vitro bone resorption by disaggregated rat osteoclasts (OC) [6], (ii) inhibits loss of osteoid and osteoblast (OB) disintegration and restores OB function in diabetic rats [7], (iii) normalizes OC ultrastructure and acid phosphatase activity in diabetic rats [8], and (iv) increases collagen synthesis in diabetic rat osteoblasts [9]. We have pursued this line of study by extending the study to chick OC and by examining the effect of TET treatment on heparin-stimulated osteoclastic bone resorption.…”

Effect of Bone Morphogenetic Protein-2 and Doxycycline on the Differentiation of Osteoprogenitors from Human Femoral Bone

“…One l of RNase H was added and incubated for 20 min at 37 °C. OCN primers (SigmaAldrich) have been used in various other studies [18][19][20]. The primer sequences used were: forward 5'ATGAGA GCCCTCACACTCCTC'3 and reverse 5'GCCGTAGAAGC GCCGATAGGC'3 to generate a 297 base pair (bp) PCRproduct.…”

“…Tetracyclines have been shown to restore or maintain bone; in diabetic and ovariectomized rats, minocycline can prevent cancellous bone loss by both inhibiting bone resorption and increasing osteoblastic activity [15][16][17][18]. We have previously shown that doxycycline decreases tumor burden in a mouse model for human breast cancer bone metastasis and increases bone formation parameters, such as osteoid volume, osteoid surface and number of osteoblasts per bone surface [19].…”