MyMedR

Displaying all 6 publications

Abstract:

Sort:

Fulltext Mixed-mode oscillations in pyramidal neurons under antiepileptic drug conditions

V-Ghaffari B, Kouhnavard M, Elbasiouny SM

PLoS One, 2017;12(6):e0178244.
PMID: 28591171 DOI: 10.1371/journal.pone.0178244

Subthreshold oscillations in combination with large-amplitude oscillations generate mixed-mode oscillations (MMOs), which mediate various spatial and temporal cognition and memory processes and behavioral motor tasks. Although many studies have shown that canard theory is a reliable method to investigate the properties underlying the MMOs phenomena, the relationship between the results obtained by applying canard theory and conductance-based models of neurons and their electrophysiological mechanisms are still not well understood. The goal of this study was to apply canard theory to the conductance-based model of pyramidal neurons in layer V of the Entorhinal Cortex to investigate the properties of MMOs under antiepileptic drug conditions (i.e., when persistent sodium current is inhibited). We investigated not only the mathematical properties of MMOs in these neurons, but also the electrophysiological mechanisms that shape spike clustering. Our results show that pyramidal neurons can display two types of MMOs and the magnitude of the slow potassium current determines whether MMOs of type I or type II would emerge. Our results also indicate that slow potassium currents with large time constant have significant impact on generating the MMOs, as opposed to fast inward currents. Our results provide complete characterization of the subthreshold activities in MMOs in pyramidal neurons and provide explanation to experimental studies that showed MMOs of type I or type II in pyramidal neurons under antiepileptic drug conditions.

Matched MeSH terms: Pyramidal Cells/drug effects; Pyramidal Cells/physiology*
Fulltext Prevention of brain hypoperfusion-induced neurodegeneration in rat’s hippocampus by black cumin fixed oil treatment

Marwan Saad Azzubaidi, Al-Ani, Imad Matloub, Anil Kumar Saxena, Ghasak Ghazi Faisal

International Medical Journal Malaysia, 2018;17(1):103-112.
MyJurnal

Introduction: The oil extract of black cumin seeds Nigella sativa (NSO) demonstrated considerable
preservation of spatial cognitive functions in rats subjected to chronic brain hypoperfusion (CBH). The hippocampal CA1 region pyramidal cells are the earliest neurons suffering neurodegeneration following CBH. Objective: The current study was devoted to assess the protective effects of Nigella sativa (NSO) treatment on CA1 hippocampal pyramidal cells of rats subjected to chronic brain hypoperfusion (CBH) that was achieved through permanent two vessel occlusion (2VO) procedure. Methods: Twenty four rats were equally divided into three groups; sham control, untreated 2VO and NSO treated group (2VO with daily oral NSO treatment. After the 10th postoperative week coronal sections of the hippocampus were collected for histopathological and electron microscopical examinations. Results: The number of viable pyramidal cells within CA1 hippocampal region in sham control and NSO treated groups was significantly higher than that of untreated 2VO group, while the difference was not significant when comparing the viable pyramidal cells number of sham control with NSO treated groups. Furthermore, 2VO group showed marked intracellular ultrastructural distortions that were less pronounced in NSO treated group. Conclusion: NSO displayed a robust potential to protect hippocampal pyramidal cells from CBH induced neurodegeneration putting forward its prospective neuroprotective activity against age related cognitive decline of Alzheimer’s disease and vascular dementia.

Matched MeSH terms: Pyramidal Cells
Fulltext Effects of electromagnetic field (EMF) on histological changes and norepinephrine levels in the brains of adult male rats

Yap, Hui Cin, Asmah Hamid, Farah Wahida Ibrahim, Nor Fadilah Rajab, Yanti Rosli

Jurnal Sains Kesihatan Malaysia, 2016;14(1):55-61.
MyJurnal

The emergence of research about the biological effects of electromagnetic field (EMF) have growing concern among
researchers. The aim of this study was to investigate the effects on the brain of rats periodically exposed to 0.1 mT EMF.
Total 24 adult male Sprague Dawley rats were subdivided randomly to 4 groups: 2 control groups (C1 6 hours: 6 h/
day for 5 days; C2 20 hours: 20 h/day for 5 days) and 2 treatment groups which exposed to 0.1 mT EMF (T1 6 hours:
6 h/day for 5 days; T2 20 hours: 20 h/day for 5 days). A significant decrease in the pyramidal cell number was higher
as the exposure duration to EMF was extended (T1, p

Matched MeSH terms: Pyramidal Cells
Housing under the pyramid reduces susceptibility of hippocampal CA3 pyramidal neurons to prenatal stress in the developing rat offspring

Murthy KD, George MC, Ramasamy P, Mustapha ZA

Indian J Exp Biol, 2013 Dec;51(12):1070-8.
PMID: 24579372

Mother-offspring interaction begins before birth. The foetus is particularly vulnerable to environmental insults and stress. The body responds by releasing excess of the stress hormone cortisol, which acts on glucocorticoid receptors. Hippocampus in the brain is rich in glucocorticoid receptors and therefore susceptible to stress. The stress effects are reduced when the animals are placed under a model wooden pyramid. The present study was to first explore the effects of prenatal restraint-stress on the plasma corticosterone levels and the dendritic arborisation of CA3 pyramidal neurons in the hippocampus of the offspring. Further, to test whether the pyramid environment would alter these effects, as housing under a pyramid is known to reduce the stress effects, pregnant Sprague Dawley rats were restrained for 9 h per day from gestation day 7 until parturition in a wire-mesh restrainer. Plasma corticosterone levels were found to be significantly increased. In addition, there was a significant reduction in the apical and the basal total dendritic branching points and intersections of the CA3 hippocampal pyramidal neurons. The results thus suggest that, housing in the pyramid dramatically reduces prenatal stress effects in rats.

Matched MeSH terms: Pyramidal Cells/metabolism*
Tualang honey consumption enhanced hippocampal pyramidal count and spatial memory performance of adult male rats

Mohd Amiruddin Kamarulzaidi, Zulkifli Mohd. Yusoff MY, Abdul Majid Mohamed, Durriyyah Sharifah Hasan Adli

Sains Malaysiana, 2016;45:215-220.

As a natural anti-oxidant source, Tualang honey, produced by wild bees nesting on the Tualang tree (Koompassia excelsa) is expected to have positive influence on health, including memory. This study investigated the effect of Tualang honey on the cell count of memory formation related hippocampal pyramidal neuron and on spatial memory performance (SMP) of rats using the radial arm maze (RAM). Sprague Dawley male rats (n=24), 7-8 weeks old were divided into two groups; experimental group group force-fed 1 mL/100 g body weight with 70% honey (HG); and the control group with 0.9% saline (CG) for 12 weeks. Nissl staining technique (with cresyl violet) was employed for neurohistological analysis of the hippocampal tissue. Six randomly selected rats from each group were used for the neuronal soma counting of pyramidal cell layer CA1, CA3a and CA3c regions. Two-way ANOVA analysis showed positively significant differences between treatment and control groups for SMP comparison of working memory and reference memory components, as well as the number of pyramidal neurons. Hence, this positive effects of Tualang honey, as demonstrated behaviorally and neurohistologically, supported report that Tualang honey could improve memory and deter hippocampal morphological impairments; possibly due to its high anti-oxidant properties.

Matched MeSH terms: Pyramidal Cells
Fulltext Role of Pre-Synaptic NMDA Receptors in the Modulation of Inhibitory Synaptic Transmission in Sensory-Motor and Visual Cortical Pyramidal Neurons in Brain Slices of Young Epileptic Mice

Lah MHC, Reza F, Begum T, Abdullah JM

Malays J Med Sci, 2018 May;25(3):27-39.
PMID: 30899185 MyJurnal DOI: 10.21315/mjms2018.25.3.4

Background: Previous studies from animal models have shown that pre-synaptic NMDA receptors (preNMDARs) are present in the cortex, but the role of inhibition mediated by preNMDARs during epileptogenesis remains unclear. In this study, we wanted to observe the changes in GABAergic inhibition through preNMDARs in sensory-motor and visual cortical pyramidal neurons after pilocarpine-induced status epilepticus.
Methods: Using a pilocarpine-induced epileptic mouse model, sensory-motor and visual cortical slices were prepared, and the whole-cell patch clamp technique was used to record spontaneous inhibitory post-synaptic currents (sIPSCs).
Results: The primary finding was that the mean amplitude of sIPSC from the sensory-motor cortex increased significantly in epileptic mice when the recording pipette contained MK-801 compared to control mice, whereas the mean sIPSC frequency was not significantly different, indicating that post-synaptic mechanisms are involved. However, there was no significant pre-synaptic inhibition through preNMDARs in the acute brain slices from pilocarpine-induced epileptic mice.
Conclusion: In the acute case of epilepsy, a compensatory mechanism of post-synaptic inhibition, possibly from ambient GABA, was observed through changes in the amplitude without significant changes in the frequency of sIPSC compared to control mice. The role of preNMDAR-mediated inhibition in epileptogenesis during the chronic condition or in the juvenile stage warrants further investigation.

Matched MeSH terms: Pyramidal Cells