Expression, activity, and localization of hormone-sensitive lipase in rat mammary gland during pregnancy and lactation

• Published in: Journal of lipid research Vol. 46; no. 4; pp. 658 - 668
• Main Authors: Martín-Hidalgo, Antonia, Huerta, Lydia, Álvarez, Nieves, Alegría, Gemma, del Val Toledo, María, Herrera, Emilio
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2005; Elsevier
• Subjects: adipocytes; Adipocytes - cytology; Adipocytes - metabolism; Aging - physiology; Animals; diacylglycerol lipase; epithelial cells; Female; Immunohistochemistry; Insulin - blood; Lactation - genetics; Lactation - metabolism; Mammary Glands, Animal - enzymology; milk; Milk - metabolism; Pregnancy - genetics; Pregnancy - metabolism; Rats; Rats, Sprague-Dawley; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sterol Esterase - genetics; Sterol Esterase - metabolism; milk; epithelial cells; immunohistochemistry; adipocytes; diacylglycerol lipase
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M400370-JLR200

We examined the presence of hormone-sensitive lipase (HSL) in mammary glands of virgin, pregnant (12, 20, and 21 days), and lactating (1 and 4 days postpartum) rats. Immunohistochemistry with antibody against rat HSL revealed positive HSL in the cytoplasm of both alveolar epithelial cells and adipocytes. In virgin rats, immunoreactive HSL was observed in mammary adipocytes, whereas diffuse staining was found in the epithelial cells. Positive staining for HSL was seen in the two types of cells in pregnant and lactating rats. However, as pregnancy advanced, the staining intensity of immunoreactive HSL increased in the epithelial cells parallel to their proliferation, attaining the maximum during lactation. An immunoreactive protein of 84 kDa and a HSL mRNA of 3.3. kb were found in the rat mammary gland as in white adipose tissue. Both HSL protein and activity were lower in mammary glands from 20 and 21 day pregnant rats than from those of virgin rats, although they returned to virgin values on days 1 and 4 of lactation. Mammary gland HSL activity correlated negatively to plasma insulin levels. Immunoreactive HSL and HSL activity were found in lactating rats' milk. The observed changes indicate an active role of HSL in mammary gland lipid metabolism.