Heterogenous response of knee cartilage to pregnancy in the rabbit: Assessment of specific mRNA levels

Abstract

Objective: The purpose of this study was to evaluate the effect of pregnancy on mRNA levels for several relevant molecules between five articular cartilage surfaces of the rabbit knee joint. Design: Total RNA was extracted from the following five knee joint articular surfaces: the lateral and medial femoral condyles (LFC and MFC); the lateral and medial tibial plateau (LTP and MTP); and the femoral groove (G) from pregnant and age- matched non-pregnant skeletally immature New Zealand White rabbits. The RNA was analysed by the sensitive molecular technique of semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) using rabbit specific primer sets. Two types of comparisons were performed: (i) comparison of mRNA levels between cartilage surfaces and (ii) comparison of mRNA levels between pregnant and non-pregnant rabbits within the same articular surfaces. Results: (i) Total RNA yield from the MFC and G represented 53 and 58% of the total RNA amount from the five cartilage surfaces in both non-pregnant and pregnant rabbits, respectively. Transcript levels for progesterone receptor (PR), aggrecan and biglycan were similar in all of the cartilage surfaces. In contrast, the cartilage surfaces exhibited significantly different transcript levels with a similar pattern for the estrogen receptor (ER), collagenase and urokinase (i.e., MTP