Distribution and synaptic connectivity of neuropeptide Y‐immunoreactive amacrine cells in the rat retina

Abstract

Neuropeptide Y (NPY) is a potent bioactive peptide that is widely expressed in the nervous system, including the retina. Here we show that specific NPY immunoreactivity was localized to amacrine and displaced amacrine cells in the rat retina. Immunoreactive cells had a regular distribution across the retina and an overall cell density of 280 cells/mm(2) in the inner nuclear layer (INL) and 90 cells/mm(2) in the ganglion cell layer (GCL). In the INL, most immunoreactive cells were characterized by small cell bodies and fine processes that appeared to ramify primarily in stratum 1 of the inner plexiform layer (IPL). A few cells in the INL also ramified in stratum 3 of the IPL. In the GCL, small to medium immunoreactive cells appeared to ramify primarily in stratum 5 of the IPL. A few immunoreactive processes, originating from somata in the INL and processes in the IPL, ramified in the OPL. NPY-immunoreactive cells contained GABA immunoreactivity, and some amacrine cells also contained tyrosine hydroxylase immunoreactivity. NPY-immunostained processes were most frequently presynaptic to nonimmunostained amacrine and ganglion cell processes and postsynaptic to nonimmunostained amacrine cell processes and cone bipolar cell axonal terminals. These findings indicate that NPY immunoreactivity is present in two populations of amacrine cells, one located in the INL and the other in the GCL, and that these cells mainly form synaptic contacts with other amacrine cells. These observations suggest that NPY-immunoreactive cells participate in multiple circuits mediating visual information processing in the inner retina.

Neuropeptide Y stimulates retinal neural cell proliferation – involvement of nitric oxide

“…Neuropeptide Y and its receptors are present in the retina of different mammalian and non-mammalian species (Bruun et al 1986;Jen et al 1994;Hutsler and Chalupa 1995;Oh et al 2002;D'Angelo and Brecha 2004). Moreover, some studies have demonstrated an early expression of NPY, suggesting that NPY may have a role in modulating the development of retinal circuitry (Ferriero and Sagar 1989;Jen et al 1994;Jotwani et al 1994;Bagnoli et al 2003).…”

Selective Ablation of a Class of Amacrine Cells Alters Spatial Processing in the Retina

“…Anatomical analyses of NPY cells in mouse and other species (Hutsler and Chalupa, 1994;Sinclair and Nirenberg, 2001;Oh et al, 2002) show that the spread of their processes is on the scale of a hundred or a few hundred micrometers. This is smaller than the size of the extended surrounds and thus argues that individual NPY cells cannot, by themselves, be generating a large surround.…”

“…The subtype chosen was a set of cells distinguished by its expression of a peptide, neuropeptide Y (NPY) (Marshak, 1989;Hutsler and Chalupa, 1994;Sinclair and Nirenberg, 2001;Oh et al, 2002), and suggested to be involved in processing spatial information (Hutsler and Chalupa, 1994). These cells form a nonrandom array across the retina, lie in two layers [the ganglion cell layer (GCL) and inner nuclear layer (INL)], and are likely inhibitory because they show immunoreactivity to GABA transporter 1 (Sinclair and Nirenberg, 2001).…”

Neuropeptide Y Receptors Y1and Y2are Present in Neurons and Glial Cells in Rat Retinal Cells in Culture

“…[6][7][8][9][10][11][12] In rodent retinas, NPY-immunoreactivity (NPY-ir) is present in the inner retina, it is localized in cell bodies at both inner nuclear layer (INL) and ganglion cell layer (GCL), and is also present in processes located in the inner plexiform layer (IPL). 11,13 NPY shows one of the highest degrees of phylogenetic preservation, compared with other neuropeptides, and does not show marked differences between species.…”