PARS GLANDULARIS AND LACTATION 



the discharge from fistulas of the breast following incision 

 for abscess. 



2. Progesterone. — Folley and Kon (1937-38) particularly 

 doubt that the inhibition of lactation during pregnancy is 

 caused by the secretion of progesterone. However, they ad- 

 mit that the inhibiting effect of oestrogen on lactation may 

 be reinforced by progesterone, which by itself is without such 

 action. In their experiments with lactating rats, they in- 

 jected I mg. of progesterone daily to the mothers from the 

 fifth day after parturition. There was no detectable effect 

 on the weight-curve of the nursing young. Anselmino, Her- 

 old, Hoffmann, and Pencharz (1936) also used rats but con- 

 cluded that progesterone can cause marked inhibition of lac- 

 tation. The authors injected 200 rat-units of prolan daily 

 for 14-18 days to bring about breast development in imma- 

 ture rats. The animals were then spayed, following which 

 (36-48 hours) lactation appeared. Almost complete inhibi- 

 tion of lactation then followed the injection of two doses of 

 0.5 unit each of progesterone, whereas the administration of 

 4,000 units of oestrogen was without effect. '^ 



3. Androgens. — Suitable doses of testosterone propionate 

 apparently can completely inhibit lactation in intact lactat- 

 ing mice or rats, whereas androsterone has practically no 

 effect (Robson, 1937; Folley and Kon, 1938). Robson in- 

 jected 0.1 mg. of testosterone propionate in oil daily to lac- 

 tating mice; nearly all the young died in less than three 

 weeks. Similar injections of 0.2 to 0.4 mg. of androsterone 

 were without action. Lactation (but not suckling or ma- 

 ternal care) rapidly disappeared, if 0.05 mg. of testosterone 

 propionate suspended in 0.05 cc. of 10 per cent alcohol were 

 injected every 2 hours. Control experiments indicated that 

 the solvent did not contribute to the effect. The observations 



'5 Folley and Kon (1938) found that the inhibitory action of oestrogen on lac- 

 tation is less readily observed in spayed animals. The possible luteinization of the 

 ovaries owing to the liberation of luteinizing hormone from the pituitary following 

 the injection of a large dose of an oestrogen seems to have been left out of considera- 

 tion. 



[163] 



