The effect of the cannabinoid-receptor antagonist, SR141716, on the early stage of kainate-induced epileptogenesis in the adult rat.

Pretreatment with the endocannabinoid-receptor antagonist, SR141716, has been reported to suppress the long-lasting hyperexcitability and increased seizure susceptibility present after 30 min of hyperthermia-induced convulsions in immature rats, an animal model of complex febrile seizures in children, which may be a cause of temporal lobe epilepsy. The present experiments tested the hypothesis that SR141716 suppresses epileptogenesis in the adult kainate model, an animal model of temporal lobe epilepsy. Adult male rats (n = 35), implanted for electroencephalography (EEG) recordings, were treated with kainate.

Chronic social stress and susceptibility to concentrated ambient fine particles in rats.

Background: Epidemiologic evidence suggests that chronic stress may alter susceptibility to air pollution. However, persistent spatial confounding between these exposures may limit the utility of epidemiologic methods to disentangle these effects and cannot identify physiologic mechanisms for potential differential susceptibilities.

Objectives: Using a rat model of social stress, we compared respiratory responses to fine concentrated ambient particles (CAPs) and examined biological markers of inflammation.

Analysis of theta power in hippocampal EEG during bar pressing and running behavior in rats during distinct behavioral contexts.

These experiments examine changes in theta power as measured by wavelet analysis in five rats performing a conditional visual discrimination task and a simple running task. In the conditional task, rats were trained to press one lever to initiate a trial and then to press one of two choice levers, each corresponding to one of two cue lights. Analysis of theta power in this operant task found a large decrease in theta power during the choice bar presses, in contrast to the increase in theta power during trial initiation bar presses.

Stimulation in hippocampal region CA1 in behaving rats yields long-term potentiation when delivered to the peak of theta and long-term depression when delivered to the trough.

Experimental evidence suggests that the hippocampal theta rhythm plays a critical role in learning. Previous studies have shown long-term potentiation (LTP) to be preferentially induced with stimulation on the peak of local theta rhythm in region CA1 in anesthetized rats and with stimulation of the perforant path at the peak of theta in both anesthetized and behaving animals. We set out to determine the effects of tetanic burst stimulation in stratum radiatum of region CA1 in awake behaving animals, delivered during either the peak or the trough of the theta rhythm in the EEG.