Low-Affinity NMDA Receptor Antagonist Hemantane in a Topical Formulation Attenuates Arthritis Induced by Freund's Complete Adjuvant in Rats.

Abstract

N-methyl-D-aspartate (NMDA) receptors that are expressed by T-cells modulate T-cell proliferation, cytotoxicity and cell migration toward chemokines. Several studies have shown an anti-inflammatory effect of NMDA receptor antagonists. This study compares the effect of the noncompetitive low-affinity NMDA receptor antagonist N-(2-adamantyl)-hexamethyleneimine hydrochloride (hemantane) in a topical formulation (gel) with the cyclooxygenase (COX) inhibitor diclofenac in a topical formulation (gel) in rats with arthritis induced by Freund's Complete Adjuvant (FCA). On day 14 after an FCA injection into the left hind paw, rats with contralateral hind paw edema were selected for further investigation (29/65). They were treated with 5% hemantane gel or 1% diclofenac gel applied locally to hind paws daily for 2 weeks starting 14 days after the FCA injection. Rats with arthritis were examined hind paw edema, hyperalgesia, and motor deficits; their body weight and hematological parameters were recorded. The rats were euthanized on day 28, followed by histological examination of the ankle joint (HE stain). Rats with arthritis exhibited hind paw inflammation and hyperalgesia, motor deficits, changes of hematological parameters, reduced weight gain and spleen hypertrophy. Histological examination of the ankle joint revealed degenerative-dystrophic lesions of the cartilaginous tissue, proliferative inflammation of the synovium, edema and lymphocytic/macrophage infiltration of periarticular tissues. Hemantane gel reduced hind paw edema, pain, motor deficits and histological signs of inflammation; its effect was comparable to diclofenac gel. Hemantane gel alleviates FCA-induced arthritis in rats, and its effect is comparable to diclofenac gel.