Lectin receptor sites during postnatal osteogenesis in guinea pigs

Osteoporosis and its complications have become widespread, affecting large portions of the world's population. More advanced information is needed on these pathologies to expand the possibilities for pathogenetic therapy.

Lectin histochemistry methods offer new insights into the structure of tissue carbohydrates and their rearrangement under physiological and pathological conditions. The aim of the present investigation was to use a set of lectins with different carbohydrate affinities to study postnatal remodelling of cartilage and bone in relation to the age and sex of experimental animals.

A panel of five conventional lectins--Con A, PNA, RCA, WGA, SNA, supplemented with an original fucose-specific lectin from Laburnum anagyroides bark (LABA)--was used to investigate the femoral bones of female and male guinea pigs aged 3 months, 1 year and 3 years. Tissue samples were fixed in 4% formaline, decalcified in 7% HNO3 and embedded in paraplast. The sections were subjected to a routine lectin-peroxidase-diaminobenzidine visualization technique.

A pronounced labeling of growth plate chondromucoid was found with Con A, PNA and SNA. Articular cartilage showed much fainter labeling with these same lectins. Capsules of isogenic groups of chondrocytes expressed a strong affinity for SNA and WGA, encompassing a predominance of Neu5Ac/2-6Gal, DGlcNAc and NeuNAc determinants. Osseomucoid showed faint reactivity with all the lectins used, while SNA distinctly marked the line of ossification. Glycoconjugates within lacunas and osseous canaliculi, as well as cytoplasmic glycoconjugates of bone and cartilage cellular elements, expressed strong labeling with RCA and SNA. Osteoclasts reacted selectively with PNA. A comparison of lectin labeling between the experimental groups indicated that the tissue reactivity of males exceeded that of females, and that aging caused a decrease in the lectin reactivity of both genders.

The data extend current knowledge regarding the selective lectin labeling of osseous tissue constituents, and demonstrate the applicability of lectin histochemistry methods in osteoporosis studies.