Protein and nucleic acid synthesis in rat mammary glands during early lactation.

Abstract

A study of the effects of hypophysectomy and various hormone replacement therapies upon rates of DNA, RNA, casein and cytoplasmic protein synthesis and enzyme activities in rat mammary glands was undertaken in an attempt to gain information regarding the effects of prolactin and cortisol upon cell proliferation and development in early lactation. Two types of enzymatic responses were observed. One type of response, characteristic of most of the enzymes studied, appeared to be closely related to gland growth and cell proliferation in that activity per mg of DNA remained constant in all hormone treatment groups. A second type of response was observed in which the activity of glucose-6-P dehydrogenase per mg DNA was increased markedly by treatment with a combination of prolactin and cortisol, indicating that the 2 hormones acted together to cause a specific increase in the activity of this enzyme. A higher relative rate of DNA synthesis in hypophysectomized rats treated with prolactin than in those not treat...