Changing distribution of GABA-like immunoreactivity in pigeon visual areas during the early posthatching period and effects of retinal removal on tectal GABAergic systems

Abstract

The distribution of GABA-like immunoreactivity in the pigeon visual system was studied during the first 9 days after hatching using a mouse monoclonal antibody, mAb 3A12, to glutaraldehyde linked GABA . GABA-like immunoreactivity was seen in cell bodies as well as in neuropil at the level of both the retina and central visual regions at any posthatching age. However, the distribution of putative GABAergic cells and processes varied with age reaching the adult pattern at around 9 days. As a general observation, almost no cell bodies in the retina (except for some perikarya in the ganglion cell layer) were labeled at hatching but densely packed immunostained processes were present in the inner plexiform layer. During the next few days, GABA-immunoreactive amacrine and horizontal cells appeared and the adult distribution of GABA-like immunoreactivity was reached at around 9 days. In the other visual regions examined, the general trend in the variation of GABA-like immunoreactivity included: (1) a progressive decrease in the density of immunostained cell bodies and (2) an almost parallel increase in the concentration of stained neuropil. Since in pigeons the adult organization of visual pathways and the final distribution of putative GABAergic systems are reached at around the same age, we suggest the possibility that incoming ganglion cell axons play a role in regulating the distribution of GABA-like immunoreactivity in visual areas. This hypothesis is supported by the fact that the distribution of GABA-like immunoreactivity in the superficial layers of the optic tectum was altered following ablation of the contralateral retina immediately after hatching.

The axon arbourisation of nuclei isthmi neurons in the optic tectum of the chick and pigeon. A Golgi and anterograde tracer-study

“…Recently GAD positivity was also found by Wang et al (2004) in the Imc neurons. The present observation supports earlier results (Dominici et al 1988;Bagnoli et al 1989; Tö mbo¨l and Ne´meth 1999) but do not completely agree with the earlier physiological observations (Wang and Frost 1991;Wang et al 1995aWang et al , 1995bWang et al , 2000Wu et al 1994). In a recent study (Wang 2003), dichotomous modulation of the receptive field of tectal neurons was reported in pigeon.…”

“…These experiments found inhibition initiated from the parvocellular nucleus (Ipc), and excitation from the magnocellular nucleus (Imc). Imunocytochemistry revealed that neurons of the Imc nucleus were GABA-positive and the neurons of the Ipc nucleus were GABA-negative (Domenici et al 1988;Bagnoli et al 1989;Tö mbo¨l et al 1995;Tö mbo¨l and Ne´meth 1998). Bagnoli et al (1989) suggested a delayed inhibition in their experiment on isthmic nuclei.…”

“…Imunocytochemistry revealed that neurons of the Imc nucleus were GABA-positive and the neurons of the Ipc nucleus were GABA-negative (Domenici et al 1988;Bagnoli et al 1989;Tö mbo¨l et al 1995;Tö mbo¨l and Ne´meth 1998). Bagnoli et al (1989) suggested a delayed inhibition in their experiment on isthmic nuclei. Both morphologists and physiologists have suggested that Ipc neurons use the neurotransmitter glycine (Hunt et al 1977;Wang and Frost 1991;Wang et al 2000).…”

Fine structure of the visual dorsolateral anterior thalamic nucleus of the pigeon (Columba livia): A hodological and GABA‐immunocytochemical study

“…These studies show that these different projections particularly affect the ventral part of the DLLv. Other light microscopic studies, using immunocytochemical techniques, have revealed the presence within the DLL of fibers immunoreactive to serotonin (Gü ntü rkü n and Challet et al, 1996), different enzymes of synthesis of catecholamines (Gü ntü rkü n and Reiner et al, 1994), ChAT (Gü ntü rkü n and Medina and Reiner, 1994), GABA (Domenici et al, 1988;Bagnoli et al, 1989;Granda and Crossland, 1989; Gü ntü rkü n and Veeman and Reiner, 1994), neuropeptide Y, and l-enkephalin (Gü ntü rkü n and . The origin of these projections is still unknown.…”

“…On the other hand, data concerning the distribution of interneurons within the DLA of the pigeon are somewhat fragmentary (Domenici et al, 1988;Bagnoli et al, 1989; Gü ntü rkü n and Veeman and Reiner, 1994). We therefore sought to augment these observations with some quantitative data, particularly with reference to the DLLv, a region in which electron microscopic observations were also made (see below).…”