Susceptibility of rat hippocampal neurons to hypothermia during development

Potential Protective Effects of Chronic Anterior Thalamic Nucleus Stimulation on Hippocampal Neurons in Epileptic Monkeys

BACKGROUND

Stimulation of the anterior nucleus of the thalamus (ANT) is effective in seizure reduction, but the mechanisms underlying the beneficial effects of ANT stimulation are unclear.

OBJECTIVE

To assess the beneficial effects of ANT stimulation on hippocampal neurons of epileptic monkeys.

METHODS

Chronic ANT stimulation was applied to kainic acid-induced epileptic monkeys. Behavioral seizures were continuously monitored. Immunohistochemical staining and western blot assays were performed to assess the hippocampal injury and the effects of ANT stimulation.

RESULTS

The frequency of seizures was 42.8% lower in the stimulation group compared with the sham-stimulation group. Immunohistochemical staining and western blot analyses indicated that neuronal loss and apoptosis were less severe and that neurofilament synthesis was enhanced in the stimulation monkeys compared with the sham-stimulation group. These data showed that the hippocampal injury was less severe in monkeys in the stimulation group than in those in the sham-stimulation group.

CONCLUSIONS

Our data suggest that chronic ANT stimulation may exert protective effects on hippocampal neurons and boost the regeneration of neuronal fibers. These effects may be closely related to the mechanisms of ANT stimulation in epilepsy treatment.

Dysfunction of thermoregulation contributes to the generation of hyperthermia-induced seizures

Febrile seizures (FS) are generally defined as seizures taking place during fever. Long-term prognosis, including development of epilepsy and malformation of cognitive function, has been demonstrated after infantile FS. However, the mechanism that triggers seizures in hyperthermic environment is still unclear. We here found that the body temperature of rat pups that experienced experimental FS was markedly decreased (∼28°C) after they were removed from the hyperthermic environment. Both the seizure generation and the temperature drop after seizure attack were abolished by either pre-treatment with chlorpromazine (CPZ), which impairs the thermoregulation, or by an electrolytic lesion of the preoptic area and anterior hypothalamus (PO/AH). However, the non-steroidal anti-inflammatory drug celecoxib did not affect the seizure incidence and the decrease in body temperature after seizure attack. In addition, pentobarbital prevented the generation of seizures, but did not reverse the decrease of body temperature after FS. Therefore, our work indicates that an over-regulation of body temperature occurs during hyperthermic environment, and that the dysfunction of thermoregulation in the PO/AH following hyperthermia contributes to the generation of FS.