Abstract
A simple quantitative test has been described for the measurement of brain seizure thresholds in mice and rats using hexafluorodiethyl ether (HFE). The test is conducted using ordinary laboratory glassware and equipment. Seizure thresholds with undiluted HFE were found to be identical to a 10% HFE-ethanol solution, which was routinely used, when the amounts of actual HFE used were measured. The test is unaffected by temperature variations over the expected range of laboratory room fluctuations. Repeated daily tests in rats do not alter the seizure threshold but do cause an earlier appearance of preconvulsive myoclonic jerks.
A comparison of the test has been made to the minimal electroshock threshold (M.E.T.) and the intravenous pentylenetetrazol (PTZ) tests using the responses to four anticonvulsant drugs, phenobarbital sodium, trimethadione, methocarbamol and diphenyihydantoin sodium. The HFE anticonvulsant parameters were found to resemble those of the PTZ test much more closely than for the M.E.T. type of electroshock test. Diphenyihydantoin produced similar anticonvulsant activity in all three tests, but was weak and irregular in action. The myoclonic jerks preceding the HFE and PTZ convulsions were more resistant to alteration by all four anticonvulsants than were the seizure thresholds. The relative merits of the three tests are compared and it is concluded that the HFE test offers a convenient substitute for the PTZ with many inherent advantages.
Footnotes
- Received December 2, 1959.
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