Effect of calcitonin on experimentally induced osteoarthritis in adult male rabbits: biochemical, histomorphometric, and immunohistochemical study

Osteoarthritis [OA] is the most common joint disease. This disease progresses slowly and develops over years. Conservative treatment regimens for OA treat the symptoms but not the disease. The purpose of this study was to investigate the role of salmon calcitonin in the changes that occur in the articular cartilage and subchondral bone following experimentally induced OA in rabbits. Thirty adult male New Zealand white rabbits were used. They were divided into three groups: control; osteoarthitic; and calcitonin-prophylactic. On sacrifice, blood samples were withdrawn to estimate serum alkaline phosphatase, calcium, and phosphorus levels. Articular cartilage and subchondral bone were processed for histological, immunohistochemical, and morphometric studies. Estimation of bone calcium and phosphorous concentrations was also carried out. Articular cartilage of osteoarthritic rabbits showed a disrupted articular surface with a reduction of the subchondral bone thickness. An irregular or a doubled tide-mark was also seen. There was a change in the normal distribution of the chondrocytes with loss of the superficial layer. Weak Periodic Acid Schiff's and Alcian blue staining with a negative BCL-2 reaction were also present in the articular cartilage. Bone calcium and phosphorus concentrations were significantly decreased in OA compared with those of the control group. Serum alkaline phosphatase level was significantly increased in the OA group compared with the control group. In the calcitonin-prophylactic group, there was an improvement in biochemical, histological, and immunohistochemical changes. Calcitonin had a protective effect on the OA changes induced in the articular cartilage of rabbits. Also, it played a role in improving bone calcium and phosphorus content and integrity of the bone matrix

protective effects of ghrelin and leptin against stress induced gastric ulcer in rats

Ghrelin and leptin hormones have been well recognised as key factors in regulating appetite and energy homeostasis. Recently, it has been reported that both are produced in the stomach, but little is known about their influence on gastric mucosal integrity. Therefore, this study aims to compare the effects of subcutaneous [sc] administration of ghrelin and leptin on acute gastric ulcer induced by immobilisation stress. The study was carried out on 36 adult male albino rats. The animals were divided into four main groups: group I [control group]; group II [ghrelin-treated group, 40 microg kg [-1] body weight [BW] sc], which was divided into two equal subgroups: group IIa [ghrelin alone] and group IIb [pretreated with nitro-l-arginine methyl ester 'L-NAME'] [70 mg kg [-1] BW sc]; group III [leptin-treated group, 10 micro g kg [-1] BW sc], which was divided into two equal subgroups: group IIIa [leptin alone] and group IIIb [pretreated with L-NAME] [70 mg kg [-1] BW sc]; and finally group IV [treated with both ghrelin and leptin]. In all the groups studied, ulcer score, ulcer index and preventive index were evaluated. sc administration of ghrelin or leptin produced a significant decrease in the ulcer score [p<0.001] and ulcer index, with an increase in the preventive index. Moreover, the combined treatment with both ghrelin and leptin induced a more protective effect than each one alone. In L-NAME-pretreated animals, the ulcer prevention ability of both ghrelin and leptin was significantly reduced [p<0.05]. However, there was still a significant reduction in the ulcer score and ulcer index when compared with that of the control rats [p<0.05]. Both ghrelin and leptin play a protective role against stress-induced gastric ulcer and their combination effect is additive in nature. Furthermore, their effects proved to be mostly, but not completely, through nitric oxide pathway