Estimation of the Number of Neurons in the Hippocampus of Rats With Penicillin Induced Epilepsy

Abstract

Epilepsy is a neurological disease arising from strong and uncontrollable electrical firings of a group of neurons in the central nervous system. Experimental epileptic models have been developed to assess the physiopathology of epileptic seizures. This study was undertaken to estimate the number of neurons in the rat hippocampus with penicillin induced epilepsy, using a stereological method, "the optical fractionator". In the experimental group, 500 IU penicillin-G was injected intra-cortically, and in the control group, the same volume of saline was administered. A week later, the animals were decapitated and their brains were removed by craniatomy. Frozen brains were cut with a thickness of 150 µm in a cryostat. Sections were collected by systematic random sampling and stained with hematoxylen-eosin. Microscopic images of pyramidal cell layers from hippocampus CA1, CA2 and CA3 subfields were then transferred to a monitor, using a 100x objective (N.A. = 1.25). Using the optical disector method, the neurons were counted in the frames and determined with a fractionator sampling scheme. The total pyramidal neuron number was then estimated using the optical fractionator method. The total pyramidal neuron number was found to be statistically lower in the experimental group (mean = 142,888 ± 11,745) than in the control group (mean = 177,953 ± 10,907) (p < 0.05). The results suggest that a decrease in the hippocampal neuronal number in a penicillin model of epilepsy can be determined objectively and efficiently using the optical fractionator method.

Cryptic sexual dimorphism in spatial memory and hippocampal oxytocin receptors in prairie voles (Microtus ochrogaster)

“…A modified version of the fractionator sampling method (Akdogan et al, 2002; West, 1993) was used to calculate cell density using the same set of brains from the volumetric analysis. After cresyl violet staining, photos were taken using our Leica microscope at 10X magnification.…”

Saccade Velocity Driven Oscillatory Network Model of Grid Cells

“…SVDON-NPCA model is capable of exhibiting place cell like activity on saccadic space when a second LAHN (place cells) layer is added after the first LAHN (SC Layer in Figure 1). Experimental Studies have shown that the number of neurons (Akdogan et al, 2011) in rat CA1 region is about 90 percent of EC (considering only layer 2 and layer 3 of MEC as they form major afferent synapse with CA1). Accordingly, a similar ratio of neurons is kept in LAHN (SC) and LAHN (PC) layers.…”

A unified hierarchical oscillatory network model of head direction cells, spatially periodic cells, and place cells

“…A–F). Anatomical studies report that (Mulders et al ., ; Akdogan et al ., ) the ratio of number of neurons in CA1 to EC (considering only layers 2 and 3 of MEC as they form major synapses with CA1; Moser et al ., ) in rats is ≈0.91. We followed the same ratio of number of neurons of LAHN PC to LAHN SC layer.…”

“…A second LAHN named as LAHN PC of smaller size, such that N PC = 0.91* N SC ; this ratio was based on the empirical reports (Akdogan et al ., ) and was placed on top of the LAHN SC , and LAHN PC was trained using the responses of LAHN SC (we have performed simulations using different network size of LAHN PC and included it as A6 Section of Appendix S1). Training equations for LAHN PC were same as that of LAHN SC (Eqns and ).…”