Combined glucosamine and chondroitin sulfate provides functional and structural benefit in the anterior cruciate ligament transection model

Evidence that combined glucosamine sulfate and chondroitin sulfate (Gluchon) or isolated glucosamine (Glu) modifies joint damage in osteoarthritis (OA) is still lacking. We studied joint pain and cartilage damage using the anterior cruciate ligament transection (ACLT) model. Wistar rats were subjected to ACLT of the right knee (OA) or sham operation. Groups received either Glu (500 mg/kg), Gluchon (500 mg/kg glucosamine +400 mg/kg chondroitin) or vehicle (non-treated—NT) per os starting 7 days prior to ACLT until sacrifice at 70 days. Joint pain was evaluated daily using the rat-knee joint articular incapacitation test. Structural joint damage was assessed using histology and biochemistry as the chondroitin sulfate (CS) content of cartilage by densitometry (microgram per milligram dried cartilage), comparing to standard CS. The molar weight (Mw) of the CS samples, used as a qualitative biochemical parameter, was obtained by comparing their relative mobility on a polyacrylamide gel electrophoresis to standard CS. Gluchon, but not Glu, significantly reduced joint pain (P < 0.05) compared to NT. There was an increase in CS content in the OA group (77.7 ± 8.3 μg/mg) compared to sham (53.5 ± 11.2 μg/mg) (P < 0.05). The CS from OA samples had higher Mw \(\left( {{\text{4}}{\text{.62}} \pm {\text{0}}{\text{.24}} \times {\text{10}}^{\text{4}} \;{{\text{g}} \mathord{\left/ {\vphantom {{\text{g}} {{\text{mol}}}}} \right. \kern-\nulldelimiterspace} {{\text{mol}}}}} \right)\) compared to sham \(\left( {{\text{4}}{\text{.18}} \pm {\text{0}}{\text{.19}} \times {\text{10}}^{\text{4}} {{\text{g}} \mathord{\left/ {\vphantom {{\text{g}} {{\text{mol}}}}} \right. \kern-\nulldelimiterspace} {{\text{mol}}}}} \right)\) (P < 0.05). Gluchon administration significantly reversed both the increases in CS content (54.4 ± 12.1 μg/mg) and Mw \(\left( {{\text{4}}{\text{.18}} \pm {\text{0}}{\text{.2}} \times {\text{10}}^{\text{4}} \,{\text{g/mol}}} \right)\) as compared to NT. Isolated Glu decreased CS content though not reaching statistical significance. Cartilage histology alterations were also significantly prevented by Gluchon administration. Gluchon provides clinical (analgesia) and structural benefits in the ACLT model. This is the first demonstration that biochemical alterations occurring in parallel to histological damage in OA are prevented by Gluchon administration.