Colocalization of GABA, enkephalin and neuropeptide Y in the tectum of thegreen frog Rana esculenta

The colocalization of GABA, enkephalin and neuropeptide Y immunoreactivity in neurons in the pretectal area and in the mesencephalic tectum of the gre en frog (Rana esculenta) was studied. Several Met-enkephalin immunoreactive perikarya were found in layer 6 of the tectum and every third of these neu rons showed GABA-ir as well. Colocalization of GABA and NPY could also be s hown in half of the neuropeptide Y immunopositive cells in the 6th layer of the tectum, but only a few cells were double stained in layers 9 and 4. In the pretectal area no colocalization of the investigated peptides and GABA was found. (C) 2001 Elsevier Science Inc. All rights, reserved.