Introduction: Carbon nanotubes (CNTs) are novel candidates in nanotechnology with a variety of increasing applications in medicine and biology. Therefore the investigation of nanomaterials’ biocompatibility can be an important topic. The aim of present study was to investigate the CNTs impact on cardiac heart rate among rats. Methods: Electrocardiogram (ECG) signals were recorded before and after injection of CNTs on a group with six rats. The heart rate variability (HRV) analysis was used for signals analysis. The rhythm-to-rhythm (RR) intervals in HRV method were computed and features of signals in time and frequency domains were extracted before and after injection. Results: Results of the HRV analysis showed that CNTs increased the heart rate but generally these nanomaterials did not cause serious problem in autonomic nervous system (ANS) normal activities. Conclusion: Injection of CNTs in rats resulted in increase of heart rate. The reason of phenomenon is that multiwall CNTs may block potassium channels. The suppressed and inhibited IK and potassium channels lead to increase of heart rate.

In chronic experiments on five groups of WAG/Rij rats (a genetic model of absence epilepsy; six animals in each group), we recorded EEG activity from the S1po cortical area through implanted electrodes and subjected the cortex to the action of four agents affecting Land T-type calcium channels (injections through an implanted cannula). A blocker of L-type channels, verapamil hydrochloride, an agonist of these channels, Bay K8644, an antagonist of T-type calcium channels, L-ascorbate, and an agonist of the latter channels, PMA, were used. The parameters of 7-to 10-Hz spike-wave discharges, SWDs, spontaneously generated in the cortex of this rat strain (frequency of SWDs, mean duration of the latter, and their number) were measured within the baseline interval (before injections) and within three subsequent 20-min-long post-injection intervals. Normal saline was injected in the control group. There were no significant differences in the mean peak frequency in SWDs between all examined groups (P > 0.05 in all cases). Verapamil significantly (by more than 40%; P < 0.05) decreased the mean SWD duration throughout the entire period of post-injection observation. The dynamics of the Bay K8644 effects were rather similar, but the intensity of SWD duration changes was somewhat smaller. Both the above agents in the doses used dramatically decreased the number (frequency of appearance) of SWDs within the observation period. L-ascorbate also suppressed SWD generation. The duration of these phenomena decreased mildly, while their number dropped dramatically. In the PMA group, the number of SWDs increased significantly (by 50%, P < 0.05) within the first 20-min-long interval, but this was not observed within subsequent intervals. These findings confirm that blocking or activating of Land T-type Ca 2+ channels in the S1po area (cortical focus area) can significantly control generation of SWDs during absence seizures. Possible mechanisms underlying actions of the tested agents are discussed.

Synchronization of bioelectrical activities of neurons contributes to the initiation of epileptiform activities occurred during a seizure attack. Absence seizures are characterized by synchronous and symmetric 2.5-4 Hz spike-wave discharges in children under 15 years old. More than half of children with absence epilepsy suffer from cognitive, education, and learning difficulties. The amplitude ratio of the theta and alpha waves is a reliable indicator for measuring of learning difficulties in children. The aim of this study was to evaluate the effect of Land T-type voltage-dependent calcium channel blockers, verapamil and ethosuximide, on the amplitude of electroencephalogram (EEG) waves in WAG/Rij rats, a genetic animal model of absence epilepsy. Materials and Methods: 18 adult WAG/Rij rats in the age between 4 and 6 months were divided randomly into 3 groups. Using stereotaxic method, cannula was implanted in the peri-oral region of the primary somatosensory cortex for injection of drugs and recording electrodes were placed in the frontal and the occipital cortices. Electroencephalography was recorded 30 minutes before and one hour after drug injection. Results: The power of EEG sub-bands significantly decreased in the first 30 minutes after injection of verapamil and ethosuximide compared to the control group. Conclusion: Our data show that verapamil and ethosuximide can decrease the power of EEG sub-bands. However, they have not noticeable effect on theta to alpha ratio.

Objective: Absence seizure as one of several kinds of seizures has been characterized by short-term episodes of either conscious or unconscious "abnormal excessive or synchronous neuronal activity in the brain. WAG/Rij rats, a genetic model of absence epilepsy, were originally developed as experimental tools to resemble human absence epilepsy. Factors like blood variation and CSF (Cerebrospinal fluid) oxidative stress and antioxidant balance, play a key role in the induction and development of absence epilepsy and its complications. In this study we tried to evaluate the effects of changes in oxidative and antioxidant levels in CSF and blood on absence seizures. Materials and Methods: 20 male WAG/Rij rats and 20 male Wistar rats (250-350g, 6-7 months old) were used in the study. At the end of the experiment animals were anesthetized, then blood and CSF samples were collected and used for the determination of Glutathione peroxidase (GPx), Superoxide dismutase (SOD), Malondialdehyde (MDA) levels and total antioxidant capacity (TAC). Results: This study showed that the level of MDA, as an index of oxidative stress, significantly increased in WAG/Rij rats when compared to control group (p=0.001 for WD and p=0.003 for CSF). It was also found that the levels of antioxidants such as GPx, SOD, and TAC in WAG/Rij rats decreased significantly: p= 0.03, p= 0.013, p= 0.001,p= 0.003, p= 0.009 and p= 0.003, respectively, for GPx WB, GPx CSF, SOD WB, SOD CSF, TAC serum and TAC CSF. Conclusion: In absence seizure, measurement of oxidative stress markers and antioxidant levels such as MDA, SOD, GPx, in serum and CSF cases can lead to a better diagnosis and treatment of this condition.

We investigated the effects of muscimol on generation of spike-wave discharges (SWDs) and short-term plasticity alterations in the somatosensory cortex of WAG/Rij rats. The rats were implanted with a twisted tripolar electrode into the above cortex region and with an intraventricular cannula into the right cerebral ventricle. EEG recordings were made before and after muscimol and saline injections. Paired-pulse stimulations (200 µsec, 100-1000 µA, 0.1 sec -1 ) were applied to the somatosensory cortex at 50-, 100-, 400-, and 500-mseclong intervals for 50 min. Pharmacological amplification of GABAergic transmission in the somatosensory cortex exerted an inhibitory effect on the thalamo-cortical circuit underlying the generation of spike-wave discharges (SWDs). Ten minutes post-injection of muscimol, paired-pulse facilitation was significantly reduced at 50-and 100-msec-long interpulse intervals (P < 0.05). The data obtained suggest that muscimol suppresses generation of SWDs and changes short-term plasticity via imitation of the effects of GABA in inhibitory synapses.