engleski

Quantification of calretinin interneurons in the medial orbital cortex of the rat and area 14 caudal in the monkey

Cortical column may have structural differences between species of different cognitive abilities. Several studies illustrate that the ratio of excitatory VS inhibitory neurons, in cortex of different species, is not constant. This variability could result from evolutionary increased number of GABAergic cells, especially those containing calretinin (CR). In order to test this hypothesis, a quantitative study of the CR neuron density was performed in the orbitofrontal cortex (OFC) of Wistar rat and Rhesus monkey. The analyzed region corresponds to agranular or dysgranular cortex, with strong hippocampal projections, i.e. medial orbital (MO) area in the rat and Brodmann area 14 caudal (14c) in monkey. Cresyl violet staining and imunohistochemical labeling for calretinin and NeuN were performed on adjacent sections throughout the entire region. Unbiased stereological method was used to estimate the total number of neurons (NeuN) and CR cells in each cortical layer of the region of interest. The rat MO region has a volume of 2.6 mm3 with ~ 115 000 NeuN cells, giving density of ~44 000/mm3. Number of CR cells in MO is ~3 000, with the density of ~ 1100/mm3. CR neurons represent 2.6% of the total neuronal population. Monkey region 14c displays a volume of 13.8 mm3 with ~ 1 050 000 NeuN cells, giving density of ~ 75 800/mm3. Number of CR cells is ~ 130 000, with density of ~9400/mm3. CR neurons represent ~12% of the entire neuronal population. This study establishes a significant difference between primates and rodents regarding CR neuron proportion.

calretinin; interneuron; neocotex; primate

nije evidentirano