Ultrastructural alterations in mammary glands of pregnant rats after ovariectomy and hysterectomy: Effect of adrenal steroids and prolactin

R. T. Chatterton, J. A. Harris, W. J. King, R. M. Wynn

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Pregnant rats were subjected to oophorectomy and hysterectomy (O-H) on the seventeenth day of pregnancy, a time when serum levels of prolactin, estrogen, and corticosterone are not substantially greater than the respective levels in nonpregnant rats. At 32 hours after O-H, serum prolactin and corticosterone both rose more than threefold, and lactose appeared in the mammary glands. Biopsies of mammary tissue obtained at 8 hour intervals after O-H showed a progressive secretory response over 16 hours, similar to that previously shown to occur within a period of about 4 hours on the last day of pregnancy. Suppression of serum prolactin by ergocriptine administration and adrenalectomy 24 hours before O-H each prevented the secretory response. However, some differences in the effects of deprivation of the two types of hormones were evident. After cortisol acetate administration at O-H, mammary tissue responded rapidly despite adrenalectomy 24 hours earlier. It is concluded that simple withdrawal of progesterone is not sufficient to initiate lactation in the pregnant rat; glucocorticoids must be present continuously during progesterone withdrawal, and prolactin elevation and other factors present at parturition may be required as well.

Original languageEnglish (US)
Pages (from-to)694-702
Number of pages9
JournalAmerican journal of obstetrics and gynecology
Issue number6
StatePublished - Jan 1 1979


ASJC Scopus subject areas

  • Obstetrics and Gynecology

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