Feline amygdaloid kindling and the sleep-waking pattern: observations on daily 22-hour polygraphic recording

PfMORC protein regulates chromatin accessibility and transcriptional repression in the human malaria parasite, Plasmodium falciparum

The environmental challenges the human malaria parasite, Plasmodium falciparum, faces during its progression into its various lifecycle stages warrant the use of effective and highly regulated access to chromatin for transcriptional regulation. Microrchidia (MORC) proteins have been implicated in DNA compaction and gene silencing across plant and animal kingdoms. Accumulating evidence has shed light on the role MORC protein plays as a transcriptional switch in apicomplexan parasites. In this study, using the CRISPR/Cas9 genome editing tool along with complementary molecular and genomics approaches, we demonstrate that PfMORC not only modulates chromatin structure and heterochromatin formation throughout the parasite erythrocytic cycle, but is also essential to the parasite survival. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) experiments suggests that PfMORC binds to not only sub-telomeric regions and genes involved in antigenic variation but may also play a role in modulating stage transition. Protein knockdown experiments followed by chromatin conformation capture (Hi-C) studies indicate that downregulation of PfMORC impairs key histone marks and induces the collapse of the parasite heterochromatin structure leading to its death. All together these findings confirm that PfMORC plays a crucial role in chromatin structure and gene regulation, validating this factor as a strong candidate for novel antimalarial strategies.

Pentylenetetrazole Kindling Affects Sleep in Rats

PURPOSE

The aim of the study was to define sleep disturbances in pentylenetetrazole (PTZ)-kindled rats and to explore the effects of the nootropic drug piracetam (Pir; 100 mg/kg) and the noncompetitive N-methyl-D-aspartate (NMDA)-antagonist MK-801 (0.3 mg/kg), which normalized learning performance in PTZ-kindled rats, on altered sleep parameters.

METHODS

This is the first report showing a significant reduction in paradoxical sleep (PS) as a consequence of PTZ kindling. A correlation analysis revealed a significant correlation between seizure severity and PS deficit.

RESULTS

Pir did not interfere with seizure severity, and the substance did not ameliorate the PS deficit. However, the substance disconnected the correlation between seizure severity and PS deficit. MK-801, which reduced the severity of kindled seizures, counteracted the PS deficit efficaciously.

CONCLUSIONS

The results suggest that seizure severity and alterations in sleep architecture are two factors in the comprehensive network underlying learning impairments associated with epilepsy. Considering the results obtained in the experiments with Pir, reduction of seizure severity does not guarantee the reduction of impairments in the domain of learning.

Kindling Limits the Interictal Neuronal Temporal Response Properties in Cat Primary Auditory Cortex

PURPOSE

The present study examined the effect of electrical kindling on the interictal temporal response properties of single units recorded from primary auditory cortex (AI) of the adult cat.

METHODS

Cats were permanently implanted with electrodes in AI, kindled twice daily for 40 sessions, and the contralateral AI was subsequently mapped. Kindling stimulation consisted of 1-s trains of biphasic square-wave pulses applied at a frequency of 60 Hz, 100 microA above the afterdischarge (AD) threshold. The EEG activity was recorded during each kindling session, and the behavioral manifestation was scored. Subsequent to kindling, multiple single-unit responses were recorded under ketamine anesthesia in response to 1-s-long periodic click trains, with click rates between 2 and 64 Hz. Neuronal responses were characterized according to their ability to respond in time-locked fashion to the clicks.

RESULTS

Kindling stimulation resulted in progression of the AD characteristics and seizure behavior, with six of 10 kindled cats reaching a fully generalized state. In the fully kindled cats, the best modulation frequencies and limiting following rates for the single-unit responses were significantly lower compared with those of naive and sham controls.

CONCLUSIONS

Repeated epileptiform activity interferes with temporal processing in cat auditory cortex in the interictal state. This may have implications for people with epileptic foci in auditory-related areas.

Long-lasting effects of feline amygdala kindling on monoamines, seizures and sleep

This report describes the relationship between monoamines, sleep and seizures before and 1-month after amygdala kindling in young cats (<1 year old; n=8; six female and two male). Concentrations (fmoles of norepinephrine or NE, dopamine or DA and serotonin or 5-HT) were quantified in consecutive, 5-min microdialysis samples (2 microl/min infusion rate) from amygdala and locus ceruleus complex (LC) during four, 6-8-h polygraphic recordings before (n=2) and 1 month post-kindling (n=2); 5-min recording epochs were temporally adjusted to correspond to dialysate samples and differentiated according to dominant sleep or waking state (lasting > or =80% of 5-min epoch) and degree of spontaneous seizure activity (number and duration of focal versus generalized spikes and spike trains and behavioral seizure correlates). Post-kindling records in each cat were divided into two groups (n=1 record each) based on higher or lower spontaneous EEG and behavioral seizure activity and compared to pre-kindling records. We found: (1) before and after kindling, NE and 5-HT but not DA concentrations were significantly lower in sleep than waking at both sites; (2) after kindling, each cat showed cyclic patterns, as follows: (a) higher NE, 5-HT and DA concentrations accompanied increased seizure activity with delayed sleep onset latency and increased sleep fragmentation (reduced sleep state percentages, number of epochs and/or epoch duration) in one recording versus (b) lower monoaminergic concentrations accompanied reduced seizure activity, rapid sleep onset and reduced sleep disruption in the other recording. The alternating, post-kindling pattern suggested "rebound" effects which could explain some controversies in the literature about chronic effects of kindling on monoamines and sleep-waking state patterns.

Ontogeny of feline temporal lobe epilepsy. III: Spontaneous sleep and arousal disorders in amygdala-kindled kittens

We report the ontogeny and persistence of sleep and arousal disorders in amygdala-kindled kittens. We also identify procedural differences that may explain discrepancies in the literature on postkindling sleep disorders. The study population consisted of 12 preadolescent kittens kindled between 2.5 and 6.5 months of age, 8 of which were followed to adulthood (> or = 1 year), and 8 unkindled implanted control animals. Sleep and seizure patterns were monitored on 12-24-h polygraphic or split-screen video recordings of EEG and behavioral activity. Kindled kittens displayed spontaneous seizure and interictal sleep anomalies that persisted to adulthood, as follows. As compared with neurosurgical controls, kindled kittens exhibited slow-wave sleep (SWS) and REM sleep insomnia at least 1 year after kindling and 1-5 months after convulsions, regardless of postictal recording delay. Sleep and arousal defects in kindled kittens were similar to but more pronounced than those in kindled adult cats, possibly because kittens spontaneously became epileptic. Detection of postkindling SWS insomnia could be masked by brief scoring epochs (less than the preferred 1-min epoch for cats); recurrent behavioral arousals after kindling frequently aborted 1-min SWS epochs but often did not interrupt 30-s SWS epochs (based on 1-min vs. 30-s minimum duration scoring criteria). Detection of postkindling REM sleep insomnia could be masked in kittens with alternating patterns of REM loss and REM rebound; all these kittens showed periodic bouts of REM onset from waking after kindling. Different data collection and analysis procedures influence detection of sleep and arousal disorders in amygdala-kindled cats when replication of findings is attempted. We conclude that these differences explain some controversies regarding the nature and prevalence of sleep disturbances in the kindling literature in temporal lobe epilepsy (TLE).

Effects of seizures, kindling, and carbamazepine on sleep organization in cats

We studied the relationships between epilepsy, sleep, and anticonvulsant drugs in kindled cats. No sleep alteration was present at midkindling. When the animals became fully kindled, a reduction in REM sleep percentage and the number of entries into REM sleep were observed compared to baseline. In addition, with further seizures, an increase in the percentage of wakefulness appeared, accompanied by a further reduction in the number of entries into REM sleep. It therefore seems that there is a progressive disruption of sleep, dependent on the increasing number of tonic-clonic generalized seizures. After a seizure-free interval, REM sleep and wakefulness returned to baseline values. A reduction in the percentage of stage II compared to baseline was found and remained as a long-term effect of the kindling process. Acute administration of carbamazepine (CBZ) reduced the REM sleep percentage. This effect, paralleled by a reduction in the number of entries into REM sleep, was evident both at baseline and when the animals were fully kindled. After a large number of seizures, however, CBZ administration did not cause a further reduction in the already low percentage of REM sleep. Results are discussed with reference to previous literature. We propose a hypothesis of competition between seizure and REM sleep in the elimination of epileptogenic and hypnogenic factors.