Subcellular distribution of delta-opioid receptors in the rat spinal cord:an approach using a three-dimensional reconstruction of confocal series ofimmunolabelled neurons

Using a specific rat monoclonal anti-idiotypic antibody eve have examined t he subcellular distribution of delta-opioid receptors in various neuronal s ubtypes of the rat spinal cord. The immunofluorescence was detected with a confocal microscope and in some cases serial images were processed for a th ree-dimensional (3-D) reconstruction of the neurons. Immunolabelling was fo und to be distributed throughout the spinal cord grey matter specially in t he most superficial layers of the dorsal horn, around the central canal and in the region of motoneurons of the ventral horn. The 3-D reconstruction m ade on large neurons of lamina IX in the ventral horn and on neurons of lam ina X around the central canal allowed the visualization of d-opioid recept ors in the cytoplasm of the soma and proximal neurites of immunofluorescent neurons. Some immunolabelled receptors were also detected at the level of the plasma membrane of the cell bodies and in the nuclear matrix. Interesti ngly, a particular arrangement of delta-opioid receptors organized along pa rallel alignments was observed on the plasma membrane of some neurons. This study emphasizes the potential usefulness of a 3-D reconstruction in the s tudy of the spatial arrangement of cellular components. (C) 1999 Elsevier S cience B.V. All rights reserved.