Effect of Insulin and Alloxan on Mammary Gland Growth in Rats

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Abstract
The synergistic effect of insulin upon mammary gland growth has been studied in adult ovariectomized rats stimulated with estradiol benzoate (EB) and progesterone (P) for 19 days. When 1, 2, and 3 units of insulin were added, mean DNA''s/100 g body weight (bw) were increased 8%, a nonsignificant increase; 17%, a significant increase; and 32%, a highly significant increase, respectively, when compared with the control group. A group of 21 rats were ovariectomized, treated with alloxan, then 2 [mu]g EB + 6 mg P were administered daily to stimulate growth of the lobule-alveolar system of the mammary gland. The mean DNA of the glands was 4.5 mg/100 g bw, a reduction of 18%, a nonsignificant decrease, below the DNA of a control group without alloxan. A 2nd group of 27 similar ovariectomized rats were treated with alloxan. They were injected with the ovarian hormones plus 3 units of insulin for the same period. The mean DNA of this group was 7.45 mg/100 g body weight, a highly significant increase of 66% in comparison with the group without insulin. Thus, the important role of insulin has been shown by its deficiency and by replacement therapy.