DIFFERENTIAL EXPRESSION OF GLYCANS IN THE HIPPOCAMPUS OF RATS TRAINED ON AN INHIBITORY LEARNING PARADIGM

HIDALGO A, BURGOS V; VIOLA H; MEDINA JH; ARGIBAY P

Neuropathology

Año: 2006 vol. 26 p. 501 - 507

0919-6544

The glycan chains of glycoconjugates play important roles in cell–cell and cell–matrix interactions. In the CNS, previous studies on learning and memory suggest the importance of oligosaccharides attached to glycoconjugates in the modulation of synaptic connections. We studied the hippocampal glycan distribution of rats subject to an inhibitory avoidance task. The expression of glycans was examined by lectin-histochemistry using Vicia villosa lectin (VVL) for terminal a/b N-acetylgalactosamine (a/b GalNAc); Galanthus nivalus lectin (GNL) for terminal mannose a-1,3 (Man a-1,3); Peanut agglutinin (PNA) for galactose b-1,3Nacetylgalactosamine (Gal b-1,3 GalNAc); Erythrina cristagalli lectin (ECL) for galactose b-1,4 N-acetylglucosamine (Gal b-1,4 GlcNAc); Sambucus nigra lectin (SNA) for sialic acid a-2.6 galactose (SA a-2,6 Gal); Maackia amurensis lectin II (MAL II) for sialic acid a-2,3 (SA a-2,3); Wheat germ agglutinin (WGA) for terminal N-acetylglucosamine with/ without sialic acid (GlcNAc wo SA); succynilated WGA (sWGA) for terminal N-acetylglucosamine without sialic acid (terminal GlcNAc without SA); Griffonia simplicifolia lectin II (GSL II) for terminal a/b N-acetylglucosamine (a/ b GlcNAc terminal); and Lotus tetragonolobus lectin (LTL) a–fucose. Two groups of 10 animals were examined: non-trained (Control) and Trained rats. ECL, sWGA and GSL II were negative for both groups in all the hippocampal subfields studied. For both groups, VVL was negative in CA4 and granular cells of the Dentate Gyrus (DG) and LTL was negative in the CA4 subfield. Expression of a/b GalNAc, a-fucose and GlcNAc in other hippocampal subfields was positive, with no differences between groups. However, expression of Man a-1,3 was significantly higher in the CA1, CA2, CA3, and CA4 subfields in the Trained group. On the other hand, expression of Gal b-1,3 GalNAc was significantly low in CA4 and DG in the Trained group. In conclusion, the results here presented indicate that the exposure of rats to an associative behavioral paradigm related to declarative memory, involves some regulatory mechanism/s for the differential patterns of glycan expression.