To look at the involvement of canonical insulin/PI3K/Akt pathway in adipocytes leptin secretion the study measured it using insulin resistant DIO mice with HFD and CD fed mice, with the HFD mice gaining higher body and fat mass. Cell lysate of both HFD and CD fed mice were subjected to western blotting and it was observed that phospho-Akt level in adipocytes from HFD fed mice was lower than the CD fed mice after insulin stimulation, showing insulin resistance in the HFD fed mice. Also, the fasting leptin level of HFD fed mice is ten times higher than the CD fed mice. Refeeding, resulted in no significant increase in plasma leptin levels in HFD fed mice after two hours, whereas with the CD fed mice there was a significant increase in plasma leptin levels. This implies that leptin production and/or secretion after refeeding is impaired in HFD fed mice. To verify that there is a decrease in systematic leptin level, the researchers isolated primary adipocytes from HFD and CD fed mice and then determined ISLS in ex vivo. The result was that ISLS was significantly lower in primary adipocytes from HFD fed mice. This supports the hypothesis that impaired ISLS in HFD fed mice in vivo and ex vivo was dependent on PI3K/Akt activation. Furthermore, there is an essential role of PI3K/Akt in regulating ISLS in primary adipocytes as seen when blocking PI3K activity with wortmannin. This significantly inhibits ISLS without affecting basal leptin secretion. Also, AKT 1/2 inhibitor Akti
Introduction
1. Normal mammary gland
1.1 normal mammary gland anatomies
The normal breast sits on the chest muscle, consisting mainly of adipose tissue, also known as mammary fat pad. The mature mammary gland is composed of 15-20 lobes, which are each composed of smaller structure called lobules. Tiny Lactiferous ducts connect lobules to each other. (Fig. 1b) (Schneider and Bocker). A typical structure of duct is composed of a hollow lumen, enclosed by a layer of epithelial luminal cells that produce