Comparative Evaluation of Enalapril and Losartan in Pharmacological Correction of Experimental Osteoporosis and Fractures of Its Background

In the experiment on the white Wistar female rats (222 animals), the osteoprotective effect of enalapril and losartan was studied on experimental models of osteoporosis and osteoporotic fractures. It was revealed that in rats after ovariectomy, the endothelial dysfunction of microcirculation vessels of osteal tissue develops, resulting in occurrence of osteoporosis and delay of consolidation of experimental fractures. Enalapril and losartan prevented the reduction of microcirculation in bone, which was reflected in slowing the thinning of bone trabeculae and in preventing the occurrence of these microfractures, as well as increasing quality of experimental fractures healing. 1. Introduction The blood flow plays a significant role in the process of bone remodeling and reparative regeneration of bone tissue [1, 2]. Microvessels of the bones have just the endothelium; they do not have the muscle and connective tissue layers. Consequently, it is the endothelium that mediates the entire humoral regulation of exchange between osteoblasts, osteoclasts, and the blood [3, 4]. At the same time in the available literature, we found no information that anyone has used the vascular endothelium of bone as a target for pharmacological action in osteoporotic changes. In our opinion, one of the reasons for the deterioration of regional blood supply of bone tissue is the endothelial dysfunction, which causes negative effects on the microcirculation that could lead to a disturbance in the processes of bone formation and osteoreparation, thereby causing osteoporosis. The increase in the frequency of osteoporosis and its complications shows that there is currently no reliable methods of drug treatment and prevention of this disease. Modern pathogenetic therapy of osteoporosis has neglected drugs with favorable effects on blood flow to bone. This indicates the actuality of research actions about osteoprotective drugs with proven positive effects on endothelium. 2. Objective To estimate the osteoprotective property of angiotensin-converting enzyme (ACE) inhibitor enalapril and angiotensin receptor blocker (ARBs) losartan on experimental models of osteoporosis and on the osteoporotic fractures. 3. Materials and Methods The experiments were conducted for 222 white female Wistar rats weighing 200–300？g. All manipulations in the experiment were performed under general anesthesia (intraperitoneal injection of chloral hydrate solution at a dose of 300？mg/kg). To study, the animals are divided into 8 groups: (i) control (intact animals) ( ); (ii) after ovariectomy ( ); (iii) after