Amphetamine as a protective agent against oxygen-induced convulsions in mice.

Male mice exposed to hyperbaric oxygen (HBO) at 4.5 ATA O2 exhibit a number of toxic symptoms including convulsions, diminished respiration and an acoustic reaction controlled by the central nervous system. To study whether stimulation of the nervous system could offer protection against the convulsions, mice were injected i.p. with various doses of d-amphetamine before HBO. At a dose of 1.0 mg X kg-1 of d-amphetamine the mice could stay at 5 ATA O2 without convulsions about three times as long as those injected with saline only. At high doses, 4 and 8 mg X kg-1, there was a weak protective effect or the time to convulsions was shortened. Amphetamine increases the release of dopamine in the brain and it is possible that the mechanisms of protection against HBO induced convulsions are involved in that process. The degree of protection, however, depends on the dose; therefore, it also is supposed that amphetamine in low doses acts on the autoreceptors with a presynaptic effect, which in this case is protective against the convulsions without affecting the respiration.