THE MAINTENANCE OF LACTATION IN THE RAT AFTER HYPOPHYSIAL ANTERIOR LOBECTOMY DURING PREGNANCY

in Journal of Endocrinology
Authors:
A. T. COWIE
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J. S. TINDAL
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SUMMARY

Experiments to determine the pituitary hormones necessary for the maintenance of lactation in the rat in the absence of either the anterior lobe of the pituitary or the entire pituitary are described.

The anterior pituitary or the whole of the pituitary was removed on the 12th day of pregnancy and prolactin (25 i.u. twice daily) plus adrenocorticotrophic hormone (ACTH) (2 i.u./day) was given to the animals from parturition to the 10th day of lactation inclusive. The lactational performances of the two operated groups of rats, as judged by the litter-growth indices, were 53% (anterior lobectomy) and 43% (hypophysectomy) of normal.

The milk-ejection reflex was completely restored in the anterior-lobectomized rats by the time of parturition, but the hypophysectomized rats required a further 2 days before milk ejection appeared to be normal.

Our experiments confirm that prolactin and ACTH are two important factors in the maintenance of milk secretion in the rat. Since only partial restoration was achieved, however, it is clear that other factors, presumably of anterior-pituitary origin, are required for the full restoration of lactation.

 

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