Comparative study of glycoconjugates of the rat prostatic lobes by lectin histochemistry

BACKGROUND. The rat prostate gland is composed of several distinct lobes: t he ventral, lateral, dorsal, and anterior (also called the coagulating glan d). Each prostatic lobe is different in its morphology, secretions, and res ponse to hormones. METHODS. The present study characterized and compared the expression of gly coconjugates in three different lobes (ventral, lateral, and dorsal) of the Noble rat prostate gland by lectin histochemistry, using a battery of 30 d ifferent lectins. RESULTS. The results indicate that different prostatic lobes elaborate and secrete different glycoconjugates. The dorsal prostatic epithelium secretes mainly in an apocrine mode, as characterized by the presence of apical cyt oplasmic blebs which are absent in the other two lobes, though merocrine se cretion is also suggested. These cytoplasmic blebs were rich in Man, GlcNAc , Gal/GalNac, Fuc, NeuAc(alpha 2,6)Gal, and oligosaccharides. Two types of cytoplasmic belbs were also identified according to their lectin bindings: blebs stained by S-Con A, LCA, PWA, UEA-II, RCA-I, DBA, EGA, WFA, Jacalin, MPA, SJA, LTA, UEA-I, PHA-E, and PHA-L, and some blebs stained by S-WGA, SE A, HAA, HPA, VAA, BPA, MAA, and SNA. The lectins, which reacted with the se cond type of blebs, also revealed some cytoplasmic granules in the dorsal p rostatic epithelial cells. The epithelium of the lateral prostate showed we ak or negative reactions to lectins, suggesting that it may express fewer g lycoconjugates as compared to the other two lobes. The epithelial Golgi reg ion of the ventral prostate is the most developed among the three lobes, an d contained abundant GlcNAc, alpha/beta-GalNAc, and NeuAc(alpha 2,6)Gal res idues, as shown by its intense reactions to S-WGA, DBA, SEA, HAA, HPA, WFA, and SNA. GS-I-B4 reacted specifically with the basal epithelial cells in a ll three lobes, indicating that glycoconjugates with terminal alpha-Gal/Gal NAc were commonly expressed in these basal cells. The basal cells in ventra l prostate might express more complex glycoconjugates, as they were also st ained by PWA, RCA-I, EGA, and PHA-L, in addition to GS-I-BC, suggesting tha t these basal cells contained more Gal(beta 1, 4)GlcNAc and Gal(beta 1,4)Gl cNAc(alpha 1,2)Man residues. GS-I-B4 and PHA-L also demonstrated a differen tial staining of the stromal smooth muscles and their associated extracellu lar matrix in the three prostatic lobes, suggesting that these structural c omponents in different prostatic lobes were different in their complex olig osaccharide contents, which probably has an influence on the epithelial-str omal interaction in the prostate. CONCLUSIONS. In summary, the present study has established for the first ti me the expression patterns of glycoconjugates in the three lobes of the Nob le rat prostate gland and suggests that certain lectins are useful as histo chemical markers for the three individual prostatic lobes. (C) 1999 Wiley-L iss,Inc.