Effect of Administration of Azithromycin and/or Probiotic Bacteria on Bones of Estrogen-Deficient Rats

Abstract

The gut microbiota plays an important role in maintaining homeostasis, including that of the skeletal system. Antibiotics may affect the skeletal system directly or indirectly by influencing the microbiota. Probiotic bacteria have been reported to favorably affect bones in conditions of estrogen deficiency. The aim of this study was to investigate the effects of azithromycin (AZM) administered alone or with probiotic bacteria (Lactobacillus rhamnosus; LR) on bones in estrogen-deficient rats. The experiments were carried out on mature rats divided into five groups: non-ovariectomized (NOVX) control rats, ovariectomized (OVX) control rats, and OVX rats treated with: LR, AZM, or AZM with LR. The drugs were administered for 4 weeks. Serum biochemical parameters, bone mineralization, histomorphometric parameters, and mechanical properties were examined. Estrogen deficiency increased bone turnover and worsened cancellous bone microarchitecture and mechanical properties. The administration of LR or AZM slightly favorably affected some skeletal parameters of estrogen-deficient rats. The administration of AZM with LR did not lead to the addition of the effects observed for the separate treatments, indicating that the effects could be microbiota-mediated.

Effects of Donepezil on the Musculoskeletal System in Female Rats

“…As previously described, a bilateral ovariectomy increased bone resorption (increasing the serum CTX-I level) [58,59] and bone formation (increasing the osteocalcin level and ALP activity) [57] in rats. Profound osteoporotic microstructure changes were demonstrated in cancellous bone in the femoral epiphysis (decreased BV/TV and Tb.Th) and in the femoral metaphysis (decreased BV/TV and Tb.N and increased Tb.Sp).…”

“…A four-week treatment in adult rats corresponds to approximately 2.5 years of the human life span [56]. This is a sufficient period to study the effects of drugs on the skeletal system in conditions of estrogen deficiency, as previously reported [57][58][59].…”

“…At this point, the apparatus automatically measured the peak force achieved by the forelimbs. Data were monitored, transferred and analyzed using a computer with data collection application (DCA) software version 2.2 (Ugo Basile, Gemonio, Italy), as previously described [57].…”

“…Bone organic substance mass was calculated by subtracting the bone mineral mass from the bone mass after lyophilization. The ratios of the bone mineral, water and organic substance to the bone mass were also calculated [57,99,100].…”

“…The measurements of the longitudinal cross-sections of the distal femoral epiphysis and metaphysis and epiphyseal cartilage were performed on decalcified and stained with hematoxylin and eosin preparations, as previously described [57,99,100]. The following histomorphometric parameters were measured in cancellous bone (the distal femoral metaphysis and epiphysis): bone volume/tissue volume ratio (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp) and trabecular number (Tb.N).…”