Effect of Corticosterone and Aldosterone Upon Milk Yield In the Rat ∗

Summary

Daily subcutaneous administration of 1 mg of corticosterone to Sprague-Dawley-Rolfsmeyer rats from day 7 to 19 of lactation stimulated increased milk secretion on days 14 to 20. On day 14 milk yield was increased 12.0%, on day 16, 13.2%, on day 18, 13.3%, on day 20, 27.0%. Higher levels of the hormone depressed milk yield, whereas a lower level of corticosterone was ineffective. Twenty-five μg aldosterone alone was either of no benefit or only slightly effective. Although the combination of 1 mg corticosterone plus 25 /xg aldosterone increased milk yield on days 14 to 20 compared with control animals, it appears that the increased milk yield is due primarily to the effect of corticosterone alone.