抄録
As for the important role played by the anterior pituitary in lactation there were not a few investigations. Removal of the hypophysis in any stage of lactation was shown to bring about an abrupt cessation of lactation (in mice: Selye,ll Collip & Thomson, 1933; Newton & Richardson, 1941, in rats : Pencharz & Long, 1933; Selye, Collip & Thomson, 1934 ; Cowie, 1957 ;
Fujii & Ueno, 1958, in guinea pigs: Pencharz & Long, 1933 ; Nelson, 1935;
Gomez & Turner, 1936, in rabbits: Frederikson, 1939, in dogs ; Lyons,w Chaikoff & Reichert, 1933). In hypophysectomized animals the lactation can be theoretically maintained by proper replacement with the pituitary hor mones. Nelson & Gaunt (1936) and Gomez & Turner (1936) could not maintain lactaion in hypophysectomized guinea pigs with prolactin alone, but could with the whole extract of hypophysis. However, the guinea pig is not suitable for the maintenance of lactation, because during its lactation period the young are not fully dependent on the mother-milk. Cowie (1957) could not maintain the lactation in hypophysectomized· lactating rats by treatment with combination of prolactin (PL), adrenocort icotrophic hormone (ACTH), somatotrophin (STH) as well as oxytocin (OX). Recently Fujii6) & Ueno
(1958) could maintain full lactation for the physiological period in hypophys・ ectomized rats by treating with combination of PL, ACTH and OX. Selye1(1934) suggested that milk secretion was maintained by PL released from14) the anterior pituitary as a result of the suckling stimulus, while Ely & Petersen(1941) postulated that the milk ejection took place by the posterior pituitar y hormone released by the similar stimuli. On the other hand, Ingelbrecht (1935) and Eayrsrn & Baddeley (1956) demonstrated that the suckling stimulus passed through the lateral funiculus of the spinal cord ascending‘to the diern Cephalon.
These facts suggest the intervening importance of the hypothalamus hypophysis axis for the lactation. Cross & Harris (1952) confirmed that the electrical stimulation of the supraopticohypophysial tract (SOT) braught about
the milk ejection in the similar way as by intravenous injection with OX in rabbits, and that electrical electrolytic lesion of SOT prevent ed the milk
ejection. It is yet obscure in this connection, whether the hypothalams only regu latesthe milk ejection reflex through the neurophpophysis, or also regulates the milk production through the adenohypophysis. This paper describes some experiments attempted for approching the role played by the hypothalamus in this regard.
