K. LISSAK AND E. ENDROCZI 307 



that ACTH, hydrocortisone and progesterone have a marked normahzing effect 

 on the EEG oi animals with chronic experimental epilepsy. 



LissAK. In our laboratory wc are domg chronic experiments registering the 

 electrical activity and introducing microcannules for recording the effects of 

 different hormones or humoral factors parallel with the electrical activity. 



CoviAN. We have been working for some years in hemidecorticate rats in 

 which changes in the weight ot the following glands were observed: adrenals, 

 thyroids, thymus, hypophysis, ovaries and seminal vesicles — Regarding adrenals 

 there was a sexual difference. Did you find any sexual difference by stimulating the 

 hippocampus? 



LisSAK. No. We have not found any sexual difference. There was a complete 

 inhibition ot the adreno-cortical activity in both sexes. 



Galambos. Over what time duration have you studied the adrenal vein level of 

 hormones? Drs Mason and Nauta at the Walter Reed Laboratories have been 

 stimulating paleocortical structures in monkey and studying adrenal hormone 

 levels in much the same way you have described. They fmd that stimulation in 

 some structures leads to profound suppression of 17-hydroxycorticosteroid output 

 for a period of days. Similarly if one stimulates a particular paleocortical structure 

 he may find the expected response from stimulation of another structure to be 

 different for many hours or days. Some ot these events thus have an astonishingly 

 long time scale. Over what time scale were your measurements made ? Could it be 

 that if you had delayed making your measurements for, say, 2 days you might have 

 found even larger responses than you have observed? 



LissAK. One of the chief difficulties of our present method of experimentation, 

 is that we need to anaesthetize the animal, because we take the blood directly from 

 the adrenal vein. Our experiments were done with stimulation times of between 

 5 to 40 1. We have not done experiments with such long stimulation. I hope that we 

 can invert our method with the modified London-cannule, and then we will look 

 for the result of longer stimulation on unanaesthetized animals. 



Porter. The initial studies indicating hippocampal inhibition of adrenocortical 

 function were done using the eosinophil count as an index of the release of corti- 

 coids. In these experiments, there was no apparent effect of electrical stimulation of 

 the hippocampus upon the level of circulating eosinophils in the blood. However, 

 known stress-evoking stimuli applied during such hippocampal stimulation failed 

 to induce their usual eosinophilic response. Subsequently Dr Mason showed that 

 there is a marked fall in the level of circulating 17-hydroxycorticosterone following 

 hippocampal stimulation which may persist for a day or two. This may be preceded 

 by a slight rise in the level of corticoids, but it is small compared with the response 

 obtained by hypothalamic or amygdala stimulation. 



I should like to sav how much I enjoyed hearing Dr Lissak's discussion ot these 

 rather complex neural-endocrine interrelationships. Considerable attention has been 

 paid in the last few years to the control which the brain exerts over the endocrine 

 system but much less has been directed towards the effects of circulating hormones 

 upon the function of the central nervous system. Dr Feldman working in Dr 

 Magoun's laboratory has shown that the adrenocortical hormones have a rather 

 consistent effect upon the non-specific systems of the bram. Usmg evoked potential 

 techniques he has found that the response in the reticular formation to sciatic nerve 

 stimulation is greatly augmented after the administration of adrenocortical 



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