EFFECT OF ADRENALECTOMY, HYDROCORTISONE ACETATE AND DESOXYCORTICOSTERONE ACETATE ON BRAIN EXCIT- ABILITY AND ELECTROLYTE DISTRIBUTION IN 2

Previous investigations in this laboratory have shown that adrenalectomy and administration of adrenocortical hormones produce predictable alterations in brain excitability (Davenport, 1949; Woodbury and Davenport, 1949; Wood-bury et al., 1951; Woodbury, 1952, 1954). The rat was the animal used in these experiments and the alternating current electroshock seizure threshold (EST) test was the procedure adopted to measure brain excitability. It was found that adrenalectomy and administration of hydrocortisone acetate (Compound F) increased brain excitability whereas desoxycorticosterone acetate (DCA) de-creased it. In the same experiments, the effects of adrenalectomy and adreno-cortical hormones on brain electrolyte metabolism were also studied; changes in the concentration of plasma and brain electrolytes were found to be associated with changes in brain excitability after hormonal treatment or deficiency. Thus, DCA administration increased plasma Na concentration, decreased intracellular brain Na concentration and increased the ratio of the two; it also decreased brain excitability. Adrenalectomy, on the other hand, decrease