IDENTIFICATION OF CELLS EXPRESSING GALECTIN-1, A GALACTOSE-BINDING RECEPTOR, IN THE RAT OLFACTORY SYSTEM

Interactions between carbohydrate ligands and their receptors play an important role in cell adhesion and migration in many tissues. Cell-su rface carbohydrates that contain terminal galactose have previously be en implicated in primary sensory axon growth in the rodent olfactory s ystem. The aim of the present study was to determine whether galectin- 1, a galactose-binding receptor, was expressed within the rat primary olfactory pathway. Immunohistochemical and in situ hybridisation analy ses revealed expression of galectin-1 by primary sensory olfactory neu rons during the major embryonic period of axonogenesis as well as in m aturity. In the adult olfactory bulb, galectin-1 was expressed by both second-order projection neurons and interneurons and was selectively localised to the synaptic neuropil layers. Mitral cells, the principal postsynaptic target of primary olfactory axons, began expressing this lectin soon after genesis and maintained high levels into adulthood. The expression of galectin-1 in the primary olfactory pathway and olfa ctory bulb neuropil suggests a role for this lectin both in the initia l formation and in the subsequent maintenance of neuronal connections between the peripheral and the central olfactory neurons as well as be tween neurons within the bulb. (C) 1995 Wiley-Liss, Inc.