Organization of Neuropeptide Y-Immunoreactive Cells in the Mongolian gerbil (Meriones unguiculatus) Visual Cortex

Abstract

Neuropeptide Y (NPY) is found throughout the central nervous system where it appears to be involved in the regulation of a wide range of physiological effects. The Mongolian gerbil, a member of the rodent family Muridae, is a diurnal animal and has been widely used in various aspects of biomedical research. This study was conducted to investigate the organization of NPY-immunoreactive (IR) neurons in the gerbil visual cortex using NPY immunocytochemistry. The highest density of NPY-IR neurons was located in layer V (50.58%). The major type of NPY-IR neuron was a multipolar round/oval cell type (44.57%). Double-color immunofluorescence revealed that 89.55% and 89.95% of NPY-IR neurons contained gamma-aminobutyric acid (GABA) or somatostatin, respectively. Several processes of the NPY-IR neurons surrounded GABAergic interneurons. Although 30.81% of the NPY-IR neurons contained calretinin, NPY and calbindin-D28K-IR neurons were co-expressed rarely (3.75%) and NPY did not co-express parvalbumin. Triple-color immunofluorescence with anti-GluR2 or CaMKII antibodies suggested that some non-GABAergic NPY-IR neurons may make excitatory synaptic contacts. This study indicates that NPY-IR neurons have a notable architecture and are unique subpopulations of the interneurons of the gerbil visual cortex, which could provide additional valuable data for elucidating the role of NPY in the visual process in diurnal animals.

The Organization of Somatostatin-Immunoreactive Cells in the Visual Cortex of the Gerbil

“…NPY and NOS have been widely used as markers for the classification of neurochemically distinct interneurons in VC [ 84 , 85 ]. The present study shows large numbers of SST neurons co-expressing NPY (80.07%) and NOS (75.41%).…”

“…All of the animals were deeply anesthetized with isoflurane (5% in O 2 ) and perfused intracardially with 4% paraformaldehyde and 0.3% glutaraldehyde in 0.1 M sodium phosphate buffer (pH 7.4) containing 0.002% CaCl 2 . Procedures for perfusion, isolation of the brain and tissue sectioning were based on those previously described [ 83 , 84 , 85 ]. The Guide for the Care and Use of Laboratory Animals ( ; accessed on 20 October 2021) was followed.…”

“…Standard immunocytochemical methods were employed as described earlier [ 83 , 84 , 85 ]. Cortical sections were double-labeled for SST with each of the following: GABA, CBPs (CB, CR, PV), NPY, NOS, CaMKII, and D 1 or D 2 dopamine receptors.…”

“…All of the methods have been described in detail elsewhere and are only summarized here [ 85 ]. For the quantitative analysis of laminar distribution, a total of 9 sections, with a width of 2000 μm each, were sampled from each of the 3 animals (3 tissue sections per animal).…”

Immunocytochemical localization of nitric oxide synthase-containing neurons in the visual cortex of the Mongolian gerbil

“…Neuropeptide Y (NPY) is one of the most highly expressed neuropeptides across the central and peripheral nervous systems of mammals [20][21][22][23]. NPY--containing neurons are distributed in layers II-VI of the gerbil visual cortex and include at least six morphologically different cell types [24]. Somatostatin (SST) exhibits widespread expression throughout the brain and plays diverse significant roles [25][26][27][28][29][30][31].…”