EFFECTS OF ENVIRONMENTAL TEMPERATURE ON PENTYLENETETRAZOL CONVULSIONS IN CORPUS CALLOTOMIZED WHITE RATS

Abstract

Following section of the corpus callosum, white rats become more sensitive than sham-operated animals to the action of pentylenetetrazol. This is shown by an increase in the duration of convulsions and incidence of clonic, tonic, and repeated convulsions which are significantly greater in corpus callotomized rats than in control animals. In addition, in the corpus callotomized rats the effects of pentylenetetrazol appear more quickly than they do in the controls.It was shown in the present investigation that exposure of the corpus callotomized and sham-operated rats to extremes of environmental temperature for 1-week periods resulted in an increased excitability and convulsibility of control animals. This effect was obtained following exposure to either low (4 °C) or tropical (34 °C) temperatures. Under similar conditions, corpus callotomized animals showed little change in convulsibility or excitability, as defined in the present study, since they had apparently reached almost a maximal state of sensitivity due to the preceding section of the commissural fibers and partial denervation of the cerebral cortical neurones; however, these animals did have a greater number of repeated convulsions when exposed to the tropical temperature, a result which may be interpreted as being due to some further increase in their sensitivity to pentylenetetrazol.