Prolonged febrile seizure history exacerbates seizure severity in a pentylenetetrazole rat model of epilepsy

The long-term neurodevelopmental outcomes of febrile seizures and underlying mechanisms

Febrile seizures (FSs) are convulsions caused by a sudden increase in body temperature during a fever. FSs are one of the commonest presentations in young children, occurring in up to 4% of children between the ages of about 6 months and 5 years old. FSs not only endanger children's health, cause panic and anxiety to families, but also have many adverse consequences. Both clinical and animal studies show that FSs have detrimental effects on neurodevelopment, that cause attention deficit hyperactivity disorder (ADHD), increased susceptibility to epilepsy, hippocampal sclerosis and cognitive decline during adulthood. However, the mechanisms of FSs in developmental abnormalities and disease occurrence during adulthood have not been determined. This article provides an overview of the association of FSs with neurodevelopmental outcomes, outlining both the underlying mechanisms and the possible appropriate clinical biomarkers, from histological changes to cellular molecular mechanisms. The hippocampus is the brain region most significantly altered after FSs, but the motor cortex and subcortical white matter may also be involved in the development disorders induced by FSs. The occurrence of multiple diseases after FSs may share common mechanisms, and the long-term role of inflammation and γ-aminobutyric acid (GABA) system are currently well studied.

Exploring the mechanism of Chaihujia Longgu Muli decoction in the treatment of epilepsy in rats based on the RhoA/ROCK signaling pathway

BACKGROUND

The Chinese herbal formula Chaihujia Longgu Muli Decoction (CD) has a good antiepileptic effect, but its mechanisms remain unclear. Therefore, in this study we explored the molecular mechanisms of CD against epilepsy.

METHODS

Twelve-day-old SD rats were randomly divided into a normal group, model group, valproic acid group, and CD high, medium, and low groups. Except for the normal group, the other groups were given an intraperitoneal injection of pentylenetetrazol (PTZ) to establish epilepsy models, and the Racine score was applied for model judgment. After 14 consecutive days of dosing, the Morris water maze test was performed. Then, hippocampal Nissl staining and immunofluorescence staining were performed, and synaptic ultrastructure was observed by transmission electron microscopy (TEM). RhoA/ROCK signaling pathway proteins were detected.

RESULTS

In PTZ model rats, the passing times were reduced, and the escape latency was prolonged in the Morris water maze test. Nissl staining showed that some hippocampal neurons swelled and ruptured, Nissl bodies in the cytoplasm were significantly reduced, and neurons were lost. Immunofluorescence detection revealed that the expression of PSD95 and SYP was significantly reduced. Electron microscopy results revealed that the number of synapses in hippocampal neurons was significantly reduced and the postsynaptic membrane length was significantly reduced. Western blot analysis showed that the RhoA/ROCK signaling pathway was activated, while SYP, SPD95, and PTEN expression was significantly decreased. After treatment with CD, neurobehavioral abnormalities and neuronal damage caused by epileptic seizures were improved.

CONCLUSION

CD exerted an antiepileptic effect by inhibiting the activation of the RhoA/ROCK signaling pathway.

Augmented impulsive behavior in febrile seizure-induced mice

Febrile seizure (FS) is one of the most prevalent etiological events in childhood affecting 2-5% of children from 3 months to 5 years old. Debates on whether neurodevelopmental consequences rise in later life following a febrile seizure or not are still ongoing however there is limited evidence of its effect, especially in a laboratory setting. Moreover, the comparative study using both male and female animal models is sparse. To examine the effect of FS on the behavioral features of mice, both sexes of ICR mice were induced with hyperthermic seizures through exposure to an infrared heat lamp. The mice were divided into two groups, one receiving a single febrile seizure at postnatal day 11 (P11) and one receiving three FS at P11, P13, and P15. Starting at P30 the FS-induced mice were subjected to a series of behavioral tests. Mice with seizures showed no locomotor and motor coordination deficits, repetitive, and depressive-like behavior. However, the FS-induced mice showed impulsive-like behavior in both elevated plus maze and cliff avoidance tests, which is more prominent in male mice. A greater number of mice displayed impaired CAT in both males and females in the three-time FS-induced group compared to the single induction group. These results demonstrate that after induction of FS, male mice have a higher susceptibility to consequences of febrile seizure than female mice and recurrent febrile seizure has a higher chance of subsequent disorders associated with decreased anxiety and increased impulsivity. We confirmed the dysregulated expression of impulsivity-related genes such as 5-HT1A and tryptophan hydroxylase 2 from the prefrontal cortices of FS-induced mice implying that the 5-HT system would be one of the mechanisms underlying the increased impulsivity after FS. Taken together, these findings are useful in unveiling future discoveries about the effect of childhood febrile seizure and the mechanism behind it.