MAMMARY GLAND AND LACTATION 



631 



fonnance as judged by the growth of the 

 litters in comparison with the growth of 

 litters of pair-fed control rats, showing that 

 apparent inhibitory effects of the alkaloids 

 on lactation were due to depressed food in- 

 take of the mothers (Tindal, 1956a). Inas- 

 much as growth of the litter depends on 

 efficient milk secretion and milk ejection, 

 Tindal's observations seem to throw doubt 

 on the importance of the adrenergic link in 

 these reflexes. On the other hand, IVIeites 

 (1959) has reported that adrenaline and 

 acetylcholine can induce or maintain mam- 

 mary development and milk secretion in 

 suitably prepared rats, observations which 

 could be interpreted as supporting the pres- 

 ence of adrenergic and cholinergic links as 

 postulated by Grosvenor and Turner 

 (1958a). 



There have been clinical reports of wo- 

 men developing galactorrhoea after treat- 

 ment with trancjuilizing drugs {e.g., Sulman 

 and Winnik, 1956; Marshall and Leiber- 

 man, 1956; Piatt and Sears, 19561 and in- 

 teresting observations have recently ap- 



peared on the lactogenic effects of reserpine 

 in animals. Milk secretion has been initiated 

 both in virgin rabbits after suitable estrogen 

 priming and in the pseudopregnant rabbit 

 by reserpine (Sawyer, 1957; Meites, 1957a). 

 On the other hand, in our laboratory Tindal 

 (1956b, 1958) had been unable to detect 

 any mammogenic or lactogenic effects with 

 chlorpromazine or reserpine in rabbits 

 (Dutch breed), rats, or goats, nor did reser- 

 pine stimulate the crop-sac when injected 

 into pigeons. Recently, using New Zealand 

 White rabbits, Tindal (1960) has induced 

 milk secretion with reserpine. The reason 

 for these contradictory results is not entirely 

 clear, although breed differences in the re- 

 sponse would appear to exist in the rabbit. 

 In our laboratory, Benson (1958) has shown 

 that reserpine is strikingly active in re- 

 tarding mammary involution in the lactat- 

 ing rat after weaning, the effect being of 

 such a magnitude as has so far only been 

 equalled by a combination of prolactin and 

 STH (Fig. 10.21). It has been tentatively 

 suggested that the tranquilizing drugs may 



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Fig. 10.2L Sections from the abdominal mammary gland of rats from whicli the pujis were 

 removed on the fourth day of lactation and which received thereafter for 9 days: A 100 fj.g. 

 reserpine daily. B. Sahne dailJ^ Note the retardation of involution effected by reserpine. 

 (Courtesy of Dr. G. K. Benson.) 



