Cellular And Molecular Neuropharmacology

The CRC Press Cellular and Molecular Neuropharmacology Series provides the reader with state-of-the-art research methods that address the cellular and molecular mechanisms of the neuropharmacology of brain function in a clear and concise format. Topics covering all aspects of neuropharmacology are being reviewed for publication. Molecular Regulation of Arousal States, Ralph Lydic Neuropharmacology Methods in Epilepsy Research, Steven L. Peterson and Timothy E. Albertson Methods in Neuro...

Body Temperature

Body temperature should be carefully monitored after both vehicle and test drug application, because changes in body temperature influence seizure susceptibility.19 Following transportation of animals from the vivarium to the laboratory, the animals should be allowed some time (e.g., 0.5 h) for acclimatization. This is very important since body temperature without this acclimatization period usually is higher by at least 0.5 C due to the stress of the move. Thus, measurement of body temperature...

AD Threshold and AD Duration

As alluded to in a previous section, the AD threshold (ADT) and associated AD duration reflect the local circuit properties of a structure and provide a relative measure of inherent excitability within a particular region.34 Many kindling studies have failed to assess these measures, relying primarily on kindling rate data or convulsive seizure disposition as a means of characterizing the epileptogenic influences of a particular treatment or the epileptogenic potential of a limbic site. In...

Electrographic Kindling in Urethane Anesthetized Rats 1 Seizure Definition

Several years ago, to explore mechanisms of epileptogenesis and changes in extracellular ions in the hippocampus, responses to stimulus trains administered to either the CA3 region of the dorsal hippocampus or to the angular bundle were characterized in the intact rat.10,11 Patterns of activation in response to trains of electrical stimulation were described in both CA1 and the dentate gyrus. Maximal activation of the dentate gyrus is characterized by the presence of bursts of large-amplitude...

Generation of Germ Line Chimeras

Following the isolation of targeted ES cell clones, chimeras are made using either blastocyst injection or, more recently, aggregation techniques (Figure 9.2). In the blastocyst injection technique, ES cells are microinjected into the fluid-filled blas-tocoel cavity of 3.5-d-old embryos at the blastocyst stage. The blastocyst injection apparatus commonly includes an inverted microscope and micromanipulation equipment. The blastocyst is positioned using a holding pipette, and 10 to 15 ES cells...

General Methodologies Utilized

For animal experiments, the first choice an investigator must make is the experimental animal model. The majority of epilepsy studies are conducted in rodents, Selected Organizations and University Research Centers Devoted to Rhythms Research Name and address Brief description Society for Research into Biological Rhythms University of Virginia Department of Biology Gilmer Hall Society for Light Treatment and Biological Rhythms 2300 RC Leiden The Netherlands San Diego Sleep and Rhythms Society...

The Subcutaneous Bicuculline and Picrotoxin Seizure Tests

In addition to PTZ, two other commonly employed chemoconvulsants include bicuculline and picrotoxin. The seizures that result from the s.c. administration of a CD97 of either chemoconvulsant results in a behavioral seizure that is for the most part indistinguishable from that produced by s.c. PTZ. The CD97 of bicuculline (Bic 2.70 mg kg) or picrotoxin (Pic 3.15 mg kg) is injected s.c. at the TPE for the test substance. Individual mice are then placed into isolation cages and observed for either...

The Subcutaneous Pentylenetetrazol Test

PTZ test is conducted in groups of mice (n 4) at two different time points (0.5 and 4 h) after the intraperitoneal (i.p.) administration of a wide range of doses (e.g., 30, 100, and 300 mg kg) of the investigational AED. These doses and times provide a preliminary estimate of the efficacy of a drug against s.c. PTZ-induced seizures. Positive results are confirmed in more extensive time- and dose-response studies (see below). All tests are conducted between 0800 and 1400 h....

Cobalt as a Focal Epileptogenic Agent

Cobalt can be employed as the metal, sometimes as powdered cobalt and sometimes in the form of cobalt wire, or as a solution of either cobaltous or cobaltic chloride. In this discussion, we will concentrate on the use of cobalt wire as the epileptogenic agent (the paper by Hattori et al.17 describes a method utilizing cobalt chloride if one is interested). The most recent purchase of cobalt wire that this author made was from Aldrich Chemical Company, Inc., St. Louis, MO. For rats, the best...

Protocol

Although the specifics of the kindling procedure will vary depending on the particular experimental question, a general description of the protocol would indicate that kindling involves administration of a low-intensity electrical stimulus to a particular region of the rat forebrain. The particular properties of the stimulus and the interstimulus interval must meet certain requirements in order for kindling to proceed (see below). During kindling, the electrographic seizures increase both in...

Pilocarpine 1 Routes of Administration

Systemic administration of pilocarpine, a cholinergic agonist, has also been used to induce SE.12 7677 The pilocarpine model of SE also shares many of the characteristics of human TLE.77 While initiation of the seizure is due to activation of the cholinergic system, the histopathology, neuronal loss, and spontaneous seizure activity occur secondary to seizure-induced glutamate release.1380 As with kainic acid, the investigator must determine whether it is necessary to implant intracranial...

The Intravenous Pentylenetetrazol Seizure Threshold Test

The IV PTZ test attempts to answer a different question from that asked by the s.c. PTZ test. As described above, the results obtained in the s.c. PTZ test are purely quantal, i.e., the drug either prevented the seizure endpoint or it did not. In contrast, the IV PTZ seizure threshold test provides an extremely sensitive parametric method for assessing seizure threshold.512 In the IV PTZ test, a drug does not have to completely prevent the occurrence of a seizure but only delay its appearance....

Spontaneous Alternation in a YMaze Test

A modified Y-maze test suitable for memory testing in mice consists of three identical compartments 10 x 10 x 10 cm each.24 The maze has no ceiling or floor and is simply put on a sheet of paper which is replaced after an animal has been tested to avoid gustatory bias in the responsiveness of the next animal. Mice are placed individually in the maze for 8 min. In this test mice explore the maze systematically, entering each arm sequentially.32 The total number of arm entries (a measure of...

Inverted Screen

In this simple test described by Coughenor and coworkers,13 also known as the wire mesh test or horizontal screen test, a single untrained drug-treated animal (usually a mouse) is put upon the grid or screen (consisting of parallel steel rods 2 mm in diameter localized 1 cm apart several groups just use commercial metal grid covers from rodent cages). The screen is then slowly rotated by 180 . The number of mice that either fall off the screen or are not able to climb to the top of the screen...

Electroshock Induced by Corneal Electrodes

The following itemization provides a description of the relatively simple technique for administering electroshock convulsions using corneal electrodes in rodents. This chapter deals solely with the use of rodents as they are the most commonly used due to their low cost and because they are a reliable model of human seizures.6-81011 While both convenient and inexpensive, electroshock convulsions can be complicated because they are expressed in a variety of forms that are dependent on the rodent...

Sample Preservation

Enzymes that metabolize extracellular chemicals do not permeate the dialysis fiber, because of their high molecular weight. This offers an advantage, as the postdialysis metabolism of the analytes is largely eliminated. Thus, the microdialysis dialysate is a chemically fixed sample from a range of sample collection times which is something a tissue biopsy or a blood plasma sample cannot provide. Despite the lack of enzymes in the dialysate some analytes are susceptible to degradation due to...

Advantages of Focal Models of Epilepsy in Experimental Animals Particularly in the

Seizures Produced Resemble those of Human Epilepsy Primary features of focal models of epilepsy in the rat are that an epileptogenic focus can be induced at a specific anatomic site and that behavioral seizures, as well as EEG spiking, can be reliably produced that resemble the human counterpart, in that they tend to be intermittent and generalized (particularly apparent after cobalt). In this respect, focal seizure models more closely resemble the human counterpart than many other models that...

Tissue Perfusion

Oxygenated ACSF perfuses the recording chamber from one end and flows over, around, and under the slices, not only providing them with glucose and oxygen, but also a medium through which slices can ultimately be exposed to drugs. Reservoirs (50 cc plastic syringes) containing the ACSF solution are connected to a miniperi-staltic pump (Harvard Apparatus, Model 55-4147, South Naticky, MA) which supplies the chamber with ACSF through tubing that is interposed between the outer and inner walls of...

References

J., Behavioural characteristics and neuronal mechanisms of amygdala kindling, Doctoral Dissertation, 1993, University of Groningen, The Netherlands. 2. L scher, W. and Schmidt, D., Which animal models should be used in the search for new antiepileptic drugs A proposal based on experimental and clinical considerations, Epilepsy Res, 10, 119, 1991. 3. Morrell, F., Kindling and Synaptic Plasticity. The Legacy of Graham Goddard, Birkhauser, Boston, 1991. 4. Goddard, G. V., The...

Motor Impairment

Acute toxicity from antiepileptic drugs in laboratory animals almost invariably is manifested by signs of neurological deficit, such as sedation, hypo- or (less often) hyperlocomotion, ataxia, abnormal gait, reduced or inhibited righting reflexes, muscle relaxation, and cognitive deficits.4 These effects are commonly referred to as neurotoxicity which, however, is somewhat misleading because some of these pharmacological actions are utilized clinically. These include the sedative and hypnotic...

Amygdala Kindling

In the absence of electrographic records, Goddard and colleagues described the sequence of behavioral seizure development resulting from daily electrical stimulation of the amygdala in the rat.8 It was reported that the initial stimulation trials failed to produce any obvious behavioral responses. It was not until several stimulations had been administered that behavioral automatisms, outlasting the kindling stimulus by several seconds, were observed. Such automatisms consisted of behavioral...

Evaluation of Seizure Severity

Seizure rating scales developed to quantitate audiogenic seizure severity in mice and rats all possess a number of similarities. All audiogenic seizure rating scales are ordinal, following the same progression no response, wild running only, generalized clonus, and finally tonic extension. There are differences in these scales based upon the characteristics of the species and preferences of the investigator. 1. Audiogenic Seizure Rating Scales in Mice Audiogenic seizures in mice are commonly...

Brain Chemistry and Seizures

There have been many studies of changes in brain chemistry associated with seizures. Generally seizures are very brief and sometimes are accompanied by violent convulsive movements. Because of the brief and violent nature of many seizures, it often is difficult to obtain an analytical sample large enough to allow accurate assessment of neurotransmitter changes that occur during the ictal phase. Although there are a few published reports of neurotransmitter changes during the ictal event,49-51...