Haitham S. Mohammed

Neurochemical and electrophysiological changes induced by paradoxical sleep deprivation in rats

The present study aims to investigate the effects of paradoxical sleep deprivation (PSD) on the waking EEG and amino acid neurotransmitters in the hippocampus and cortex of rats. Animals were deprived of paradoxical sleep for 72h by using the multiple platform method. The EEG power spectral analysis was carried out to assess the brains electrophysiological changes due to sleep deprivation. The concentrations of amino acid neurotransmitters were assessed in the hippocampus and cortex using HPLC. Control data showed slight differences from normal animals in the delta, theta and alpha waves while an increase in the beta wave was obtained. After 24h of PSD, delta relative power increased and the rest of EEG waves power decreased with respect to control. After 48h and 72h the spectral power analysis showed non-significant changes to control. The amino acid neurotransmitter analysis revealed a significant increase in cortical glutamate, glycine and taurine levels while in the hippocampus, glutamate, aspartate, glutamine and glycine levels increased significantly. Both the waking EEG and neurotransmitter analyses suggest that PSD induced neurochemical and electrophysiological changes that may affect brain proper functionality.

A promising therapeutic potential of cerebrolysin in 6-OHDA rat model of Parkinson's disease

AIMS Parkinsons disease (PD) is the second most prevalent neurodegenerative disease affecting the population. The present study investigates the potential therapeutic effect of cerebrolysin (CBL), as a neurotrophic factor mimic, on the behavioral and biochemical alterations induced in 6-hydroxydopamine (6-OHDA) - lesioned rats as a model of PD. MAIN METHODS The animals were divided into 3 experimental groups; control group, Parkinsonian model group through bilateral microinjection of 6-OHDA into substantia nigra (SN) and CBL-treated group which received a daily intraperitoneal administration of CBL (2.5ml/kg) initiated 24h after induction of Parkinsonism for 21days. KEY FINDINGS Treatment of Parkinsonian animals with CBL succeeded in restoring the midbrain and striatum dopamine levels. In addition, it normalized the increased MDA and NO levels recorded in the Parkinsonian animals and replenished the decreased level of midbrain GSH. In addition to the recorded recovery of the biochemical parameters, there was a parallel improvement in the animals behavioral aspects. SIGNIFICANCE The findings of the present study provide evidence for the promising therapeutic effect of CBL in the present 6-OHDA rat model of PD through counteracting oxidative stress, replenishing dopamine content and enhancing behavioral outcomes.

Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats

In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested.

Electroencephalographic and biochemical long–lasting abnormalities in animal model of febrile seizure

Febrile seizures (FS) are convulsions associated with high body temperature. It has a high incidence in children from the age of 6months to 5years and may have adverse consequences in adulthood. The experimental model of FS could be induced in animals via hyperthermia. The present study was designed to investigate persistent electroencephalographic (EEG), neurochemical and behavioral alterations in adult animals that had experienced complex FS at their immature age. EEG signals were obtained from the cortex of both FS and control normothermic groups of animals. A spectrophotometric assay was carried out to determine oxidative stress parameters (malondialdehyde, nitric oxide, reduced glutathione) and acetylcholinesterase activity in the cortex and hippocampus of FS and control animals. Behavioral assessment of seizure threshold and severity were investigated via a sub-convulsive dose of nicotine in adult animals. Alterations in the oxidant/antioxidant system and AChE activity were obtained in the cortex and hippocampus of FS animals in comparison to control animals. EEG spectral analysis displayed significant changes in all EEG frequency bands. A decrease in seizure latency and an increase in seizure severity were also observed. The present study provides evidence for long-lasting abnormalities in the cortex and hippocampus of adult animals subjected to complex FS at their developmental age, which may be correlated to the underlying mechanism of epileptogenesis and its related co-morbidities.

A miniature microdrive for recording auditory evoked potentials from awake anurans.

Electrical activity recording from the brains of awake animals is a corner stone in the study of the neurophysiological basis of behavior. To meet this need, a microelectrode driver suitable for the animal of interest has to be developed. In the present study a miniature microdrive was developed specifically for the leopard toad, Bufo regularis, however, it can be used for other small animals. The microdrive was designed to meet the following requirements: small size, light weight, simple and easy way of attaching and removing, advancing and withdrawing of microelectrode in the animal brain without rotation, can be reused and made from inexpensive materials. To assess the performance of the developed microdrive, we recorded auditory evoked potentials from different auditory centers in the toads brain. The potentials were obtained from mesencephalic, diencephalic and telencephalic auditory sensitive areas in response to simple and complex acoustic stimuli. The synthetic acoustical tones introduced to the toad were carrying the dominant frequencies of their mating calls.

Cerebellar neurochemical and histopathological changes in rat model of Parkinson's disease induced by intrastriatal injection of rotenone.

The aim of the present work was to investigate the neurochemical changes induced in the cerebellum of rat model of Parkinsons disease (PD). Rats were divided into two groups; control and rat model of PD induced by the intrastriatal injection of rotenone. As compared to control, a significant increase in the excitatory amino acid neurotransmitters; glutamate and aspartate together with a significant decrease in the inhibitory amino acids, GABA, glycine and taurine were observed in the cerebellum of rat model of PD. This was associated with a significant increase in lipid peroxidation, nitric oxide and tumor necrosis factor-α and a significant decrease in reduced glutathione. A significant decrease in acetylcholinesterase and a significant increase in Na+,K+-ATPase were recorded in the cerebellum of rat model of PD. In addition the cerebellar sections from rat model of PD showed marked necrosis of Purkinje cells, irregular damaged cells, cytoplasmic shrinkage, necrosis and perineuronal vacuolation. The present results indicate that the disturbance in the balance between the excitatory and inhibitory amino acids may have a role in the pathogenesis of PD. According to the present neurochemical and histopathological changes, the cerebellum should be taken into consideration during the treatment of PD.