Early morphological changes in the knee joint of rats after opioid exposure

Abstract

The objective is to study early morphological changes of rats’ knee joint after experimental opioid exposure. Materials and methods. Research material is mature, non-breeding male rats 4.5 months old (n = 16) with body weight 80 g. Animals were divided into 2 groups: experimental and control. The experimental group of rats (n = 10) got the injection of nalbuphine hydrochloride intramuscularly, one time per day during 7 days; initial dose – 8 mg/kg. The condition of chronic opioid exposure has been modeled. The rats of control group (n = 6) got the injection of physiological solution intramuscularly during 7 days. The distal epiphysis of rat thigh and proximal epiphysis of rat tibia taking into account the preservation of topographical correlation of the knee joint structural components have been used for histological analysis. Following decalcination, the histologic specimens have been stained with hematoxylin, eosin, azure and azan by Heidenhain. The thickness of the cover synovial layer of articular cartilage has been measured. Results. The architectonics of articular cartilage distorts, the cover synovial layer of articular cartilage gets thinner due to experimental action of opiates. There is also tendency towards volume decrease of chondrocytes in proliferation zone and thickness loss of the cartilage. Conclusions. At the early stage of opioid exposure the structure abnormality of laboratory rats’ knee joint can be seen in the synovial layer and in the zone of chondrocytes proliferation. These research data can be a prerequisite for opioid chondropathy.