Behavioral alterations in the pilocarpine model of temporal lobe epilepsy in mice
Introduction
Most patients with epilepsies have to cope not only with the disease itself but also with many additional medical problems that may be associated with epilepsies (Boro and Haut, 2003). Of all medical comorbidities associated with epilepsy, psychiatric disorders are the most common (Boro and Haut, 2003, Swinkels et al., 2005). Mood disorders, predominantly major depression, and anxiety disorders have the highest frequency, followed by psychosis (Boro and Haut, 2003, Devinsky, 2003). Psychopathology may coexist with epilepsy, may be directly related to seizure activity, or may be associated with the postictal state (Boro and Haut, 2003). The neurobiological mechanisms of the relationship between epilepsy and psychopathology are poorly understood and systematic research in this area is still lacking (Devinsky, 2003, Swinkels et al., 2005). Apart from psychiatric disorders, many patients with epilepsy suffer from impaired cognitive performance (Motamedi and Meador, 2003). The type of neuropathology associated with epilepsy may affect the type of cognitive dysfunction. For instance, temporal lobe epilepsy (TLE) with hippocampal sclerosis is often associated with memory impairment (Motamedi and Meador, 2003).
Animal models of epilepsy are useful to enhance our understanding of causal mechanisms underlying the association between epilepsy and behavioral abnormalities (Post, 2004, Majak and Pitkanen, 2004, Heinrichs and Seyfried, 2006). Most studies in this respect have used the kindling model and post-status epilepticus (SE) models of TLE in rats, whereas mouse models of TLE have received much less attention. Mice offer gene targeted technologies for in vivo gene function analysis that may be invaluable in unraveling the complex relationship between epileptogenesis, neurodegeneration and behavioral and cognitive abnormalities.
One of the most prominent models of TLE in rats and mice is the pilocarpine model (Turski et al., 1989, Cavalheiro et al., 1996, Coulter et al., 2002, Cavalheiro et al., 2006). The induction of SE by systemic administration of pilocarpine, a cholinergic muscarinic agonist, in rodents leads to epilepsy with spontaneous recurrent seizures (SRS) and hippocampal alterations that are reminiscent of hippocampal sclerosis in patients with TLE. Furthermore, alterations in learning and memory as well as behavioral dysfunction have been described in the pilocarpine model in rats. Surprisingly, although the acute convulsive and neurodegenerative effects of pilocarpine in mice were first reported in 1984 (Turski et al., 1984) and SRS following a pilocarpine-induced SE in mice in 1996 (Cavalheiro et al., 1996), to our knowledge the long-term behavioral alterations occurring in this model have not been characterized in detail in this species since then. This prompted us to perform a study with behavioral phenotyping of pilocarpine-treated mice, using behavioral test batteries to investigate locomotor activity and function, learning and memory, emotionality, depression-related behavior and other types of psychopathology. The study was undertaken in three subsequent parts as follows. (1) Because the systemic administration of convulsant doses of pilocarpine in mice is often associated with high mortality and/or a low percentage of mice developing or surviving SE (Shibley and Smith, 2002, Borges et al., 2003, Winokur et al., 2004, Borges et al., 2006), we compared different application and dosing protocols for pilocarpine to obtain a protocol yielding a high percentage of mice with SE but low mortality (“study #1”). (2) Because mortality, hippocampal damage and incidence of animals with SRS is affected by the duration of SE (Lemos and Cavalheiro, 1995, Goodman, 1998, Glien et al., 2001), we terminated SE after 1, 1.5 or 2 h and investigated the long-term consequences (“study #2”). (3) The pilocarpine protocol thus developed was used to study the behavioral and cognitive alterations developing in mice in this model of TLE (“study #3”). Some of the results have been presented in abstract form (Groeticke et al., 2006).
Section snippets
Animals
As in previous studies of our group (Löscher and Lehmann, 1996, Löscher and Lehmann, 1998, Wlaz et al., 1998b, Potschka and Löscher, 1999, Löscher et al., 2003), we used adult female outbred NMRI mice, which were obtained from a commercial breeder (Harlan-Winkelmann, Borchen) at an age of about 5–6 weeks. Female mice were used for the present study to ease housing in groups for the long period needed to perform all experiments (see below). After arriving at our Department, animals were housed
Comparison of different application and dosing protocols for pilocarpine
In a first preliminary experiment, single i.p. doses of pilocarpine were tested in mice (Table 1). The range of doses (200–360 mg/kg) covered the dose range previously reported for different mouse strains (Turski et al., 1984, Cavalheiro et al., 1996, Shibley and Smith, 2002, Borges et al., 2003, Winokur et al., 2004). Within a few minutes after pilocarpine injection, immobility, staring, Straub tail, head nodding and occasional clonic seizures occurred, but a SE with continuous seizure
Discussion
Pilocarpine is frequently used to induce SE in mice, but systemic (i.p.) injection of high doses is often associated with high mortality and/or a low percentage of mice developing or surviving SE (Shibley and Smith, 2002, Borges et al., 2003, Winokur et al., 2004, Borges et al., 2006). In a first series of preliminary experiments with administration of high i.p. doses of pilocarpine in NMRI mice, only few of the mice developed SE, but mortality was high. This prompted us to perform experiments
Acknowledgments
We thank Prof. H. Emrich (Department of Clinical Psychiatry and Psychotherapy, Medical School Hannover, Germany), Prof. S. Steinlecher (Department of Zoology, University of Veterinary Medicine Hannover, Germany), and Prof. J.P. Huston and his colleagues (Institute of Physiological Psychology, Center for Biological and Medical Research, University of Düsseldorf, Germany) for helpful discussions and advice during establishment of the behavioral models and interpretation of data obtained in these
References (83)
- et al.
Functional inactivation of a fraction of excitatory synapses in mice deficient for the active zone protein bassoon
Neuron
(2003) - et al.
Mouse defensive behaviors: pharmacological and behavioral assays for anxiety and panic
Neurosci. Biobehav. Rev.
(2001) - et al.
Neuronal and glial pathological changes during epileptogenesis in the mouse pilocarpine model
Exp. Neurol.
(2003) - et al.
Degeneration and proliferation of astrocytes in the mouse dentate gyrus after pilocarpine-induced status epilepticus
Exp. Neurol.
(2006) - et al.
N-methyl-D-aspartate receptor blockade after status epilepticus protects against limbic brain damage but not against epilepsy in the kainate model of temporal lobe epilepsy
Neuroscience
(2003) - et al.
Treatment with valproate after status epilepticus: effect on neuronal damage, epileptogenesis, and behavioral alterations in rats
Neuropharmacology
(2006) Antagonists of the NMDA receptor–channel complex and motor coordination
Life Sci.
(1995)- et al.
The pilocarpine model of seizures
- et al.
Expression analysis of metabotropic glutamate receptors I and III in mouse strains with different susceptibility to experimental temporal lobe epilepsy
Neurosci. Lett.
(2005) - et al.
Anticonvulsant action and long-term effects of gabapentin in the immature brain
Neuropharmacology
(2001)
The functional anatomy and pathology of lithium–pilocarpine and high-dose pilocarpine seizures
Neuroscience
Preliminary report of a simple animal behavior model for the anxiolytic effects of benzodiazepines
Pharmacol. Biochem. Behav.
The tail suspension test as a model for assessing antidepressant activity: review of pharmacological and genetic studies in mice
Neurosci. Biobehav. Rev.
Effects of anxiety on attentional allocation and task performance: an information processing analysis
Behav. Res. Ther.
Behavioral changes resulting from the administration of cycloheximide in the pilocarpine model of epilepsy
Brain Res.
A note on a simple apparatus for detecting neurological deficit in rats and mice
J. Am. Pharm. Assoc.
Repeated low-dose treatment of rats with pilocarpine: low mortality but high proportion of rats developing epilepsy
Epilepsy Res.
Chronic elevation of brain GABA levels beginning two days after status epilepticus does not prevent epileptogenesis in rats
Neuropharmacology
Behavioral seizure correlates in animal models of epilepsy: a road map for assay selection, data interpretation, and the search for causal mechanisms
Epilepsy Behav.
Characterization of lithium potentiation of pilocarpine-induced status epilepticus in rats
Exp. Neurol.
Influence of paternal genotypes on F1 behaviors: lessons from several mouse strains
Behav. Brain Res.
Age-related changes in spontaneous behavior and learning in NMRI mice from middle to old age
Physiol. Behav.
Pharmacology of glutamate receptor antagonists in the kindling model of epilepsy
Prog. Neurobiol.
Which animal models should be used in the search for new antiepileptic drugs? A proposal based on experimental and clinical considerations
Epilepsy Res.
Responses to NMDA receptor antagonists altered by epileptogenesis
Trends Pharmacol. Sci.
Strategies in antiepileptic drug development: is rational drug design superior to random screening and structural variation?
Epilepsy Res.
Anticonvulsant efficacy of l-deprenyl (selegiline) during chronic treatment in mice: continuous versus discontinuous administration
Neuropharmacology
Are neuronal nicotinic receptors a target for antiepileptic drug development? Studies in different seizure models in mice and rats
Eur. J. Pharmacol.
Patterns of seizures, hippocampal injury and neurogenesis in three models of status epilepticus in galanin receptor type 1 (GalR1) knockout mice
Neuroscience
Intact spatial memory in mice with seizure-induced partial loss of hippocampal pyramidal neurons
Neurobiol. Dis.
Spatial learning in male mice with different levels of aggressiveness: effects of housing conditions and nicotine administration
Behav. Brain Res.
Kindling and status epilepticus models of epilepsy: rewiring the brain
Prog. Neurobiol.
Developments of a water-maze procedure for studying spatial learning in the rat
J. Neurosci. Methods
Assessment of learning by the Morris water task and fear conditioning in inbred mouse strains and F1 hybrids: implications of genetic background for single gene mutations and quantitative trait loci analyses
Neuroscience
The open field as a paradigm to measure the effects of drugs on anxiety-like behaviors: a review
Eur. J. Pharmacol.
Antidepressant-like effects in various mice strains in the tail suspension test
Behav. Brain Res.
Fluoro-Jade C results in ultra high resolution and contrast labeling of degenerating neurons
Brain Res.
Psychosis: pathological activation of limbic thalamocortical circuits by psychomimetics and schizophrenia?
Trends Neurosci.
Pilocarpine-induced status epilepticus results in mossy fiber sprouting and spontaneous seizures in C57BL/6 and CD-1 mice
Epilepsy Res.
Temporal lobe seizures alter the amplitude and timing of rat behavioral rhythms
Epilepsy Behav.
The excitatory amino acid antagonist D-CPP-ene (SDZ EAA-494) in patients with epilepsy
Epilepsy Res.
Cited by (171)
The applications of the pilocarpine animal model of status epilepticus: 40 years of progress (1983–2023)
2023, Behavioural Brain ResearchPirarubicin loaded biodegradable nanoparticles downregulate IL-6, COX-II and TNF-α along with oxidative stress markers in comparison to conventional pirarubicin in healthy albino rats
2023, Journal of Drug Delivery Science and TechnologySubstantial outcome improvement using a refined pilocarpine mouse model of temporal lobe epilepsy
2021, Neurobiology of DiseaseAn inventory of basic research in temporal lobe epilepsy
2021, Revue Neurologique