Asian Elm tree inner bark prevents articular cartilage deterioration in ovariectomized obese rats with monoiodoacetate-induced osteoarthritis

Abstract

Objective: We investigated whether long-term consumption of Korean mistletoe or Asian Ulmi cortex would prevent or delay menopausal symptoms and progression of osteoarthritis in estrogen-deficient obese rats.

Methods: Ovariectomized (OVX) rats were provided a 45% fat diet containing either (1) 0.6% lyophilized water extract of Korean mistletoe (KME) + 1.4% dextrose (KME; n = 10), (2) 2% lyophilized water extract of Ulmi cortex (UCE; n = 10), (3) 30 μg/kg bw 17β-estradiol + 2% dextrose (positive control; n = 10), (4) 2% dextrose (placebo; OVX-control; n = 10), or (5) 2% dextrose (normal-control; n = 10) for 4 weeks. At the beginning of the 5th week, OVX rats, except in the normal-control group, were given articular injections of monoiodoacetate into the right knee and the assigned diets were provided for an additional 3 weeks. The rats in the normal-control had injections of saline into the right knee.

Results: KME, but not UCE, partially prevented the insulin resistance and the loss of bone mineral density and lean mass. The limping scores were lower in the descending order of the OVX-control > KME and 17β-estradiol > UCE > normal-control at day 14 and 21 (P < 0.05). The scores for pain behaviors measured by weight distribution on the right leg, maximum running velocity on a treadmill and locomotive activity, were markedly decreased in the same order as limping scores. Monoiodoacetate increased the expression of matrix metalloprotinase-3 and metalloprotinase-13 in the articular cartilage and elevated the production of inflammatory markers such as tumor necrosis factor-α, interleukin-1β, and interleukin-6, but they were lower in the UCE than in the other groups (P < 0.05). Histology of the right knee revealed cartilage damage near the tidemark of the knee and proteoglycan loss was markedly less in UCE.

Conclusions: UCE was an effective therapeutic agent for preventing osteoarthritis and KME prevented decreases in lean body mass, bone mineral density, and insulin sensitivity in estrogen-deficient rats.