174 DiscussiOiN 



Jost: I wish to introduce a remark about some papers claiming that 

 growth hormone injected into pregnant rats produces foetal gigantism. 

 I must say that a careful examination of the published tables often 

 leads to other conclusions than those expressed by the author in the 

 text accompanying the tables. I know of no clear demonstration of 

 foetal gigantism induced by growth hormone. 



T.-Duplessis: No, they got a very large foetus of about 8 g. and they 

 did tremendous work in measuring the different endocrine glands, and 

 where these glands were larger and so forth, they tried to explain that 

 also by growth hormone secretion or pathological aspects, for instance 

 in a diabetic mother. But I think that they were always dealing with 

 older embryos. 



Huggett: At the end of the war, Dr. Deryk Fraser and I were interested 

 in foetal growth and the relationship between growth hormone and 

 diabetogenic hormone and the effect on growth gonadally, so we injected 

 growth hormone, which we got from Prof. Frank Young, and we found, 

 as Prof. Tuchmann-Duplessis has found, that the foetuses were smaller. 

 But we also found, as he did, that if you injected not at the beginning 

 of conception but after 5 days, it had no effect, and that gave us the 

 clue and we worked out that in fact what we were dealing with was 

 delayed implantation due to the presence of impurity. We proved this 

 because later Prof. Young produced a very pure growth hormone, 

 completely free of gonadotropin, and we found that it was completely 

 inactive and had no effect whatsoever. 



Like Prof. Jost, we came to the same conclusions on reading some of 

 the published papers— that our conclusions differed from the authors'. 

 Strauss: I would like to know where the growth hormone came from? 

 Is it a pure hormone or a complex one? 



T.-Duplessis: We tried two types of growth hormone, a crystalline 

 one prepared by Li in California and a commercial brand (Choay 

 Laboratories) in which there may have been gonadotrophins. I think 

 we have to bear in mind that these hormones only modify the environ- 

 ment of the mother — they do not cross the placental barrier. It was 

 demonstrated by many people that pituitary hormone, which, like 

 ACTH, has a lower molecular weight does not cross the placental barrier. 

 Strauss: But if growth hormone does contain gonadotrophic hormone, 

 then gonadotrophic hormones may be produced by the placenta itself. 

 T.-Duplessis: But the results were the same whether you have a 

 preparation which you are quite sure does not contain gonadotrophin 

 or one which does. It is only the mortality or abortion rate which is 

 higher if you have a mixture of both. This is very significant in the 

 experiments reported by Nixon. 



Huggett: Swyer and Fouracre Barns also investigated this same 

 problem using pure growth hormone, and got the same result as we got, 

 namely the entire negative effects. 



Williams: If growth hormone only acts if it is given before the 5th day, 

 you can conceive that this is the period when pituitary luteotrophin is 

 active and that by inhibiting production of this you delay implantation. 

 If you are giving very high doses of growth hormone you may depress 



