Abstract
It is well-known that destruction of the brain causes increase of reflex action in frogs, especially when they are kept in the cold, and last year I reported that the effect of morphin, which causes in frogs tetanus indistinguishable from that of strychnin, was very markedly increased by decerebration, the effective dose in such frogs being about one tenth of that in normal frogs.
I wish to report now on the result of a study of the effect of decerebration upon the convulsant action of caffein. Caffein salts which are strongly acid cause a peculiar muscular stiffness which masks the central action. The alkaloid itself causes also a certain muscular stiffness but it is much less marked and is only troublesome with large doses. The alkaloid was therefore used in these experiments. As was the case with other convulsant drugs we found the action of caffein much greater in the cold. If the frogs are kept cold tetanus can be obtained with doses which are too low to markedly affect the muscles.
In contrast to morphin we found that both in the cold (2-5° C.) and in the warm (12-18° C.) there was no difference between normal and decerebrate frogs in their response to the convulsant action of caffein. In both tetanus was obtained in the cold in all frogs with doses of 0.2 mg. p. gm. and in most frogs with 0.1 mg. p. gm. At room temperature tetanus was constantly obtained in normal decerebrate frogs with doses of 0.6 mg. p. gm. but never in either with 0.3 mg. p. gm.
The experiments show that there is a difference of some sort between the actions of caffein and morphin on the central nervous system although the convulsions are identical in appearance.
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