Department of Biology, Utah State University, 4715 Old Main Hill, Logan, UT 84322-4715, US.
Brain Res. 2013 Nov 6;1537:191-200. doi: 10.1016/j.brainres.2013.09.025. Epub 2013 Sep 25.
Insulin injections into the central nucleus of the amygdala (CeA) inhibit food intake but this response is lost quickly on feeding a high fat diet. The purpose of the studies described in this manuscript was to identify the potential mechanism for the development of this insulin resistance. High fat diets (HFD) induced PKCθ activation and blocked the stimulation of Akt but not mTOR phosphorylation in the amygdala in response to CeA insulin injections. Infusions of palmitic acid onto the CeA had identical effects to HFD on PKCθ expression and insulin signaling in the amygdala. CeA insulin also induced an increase in Akt phosphorylation in the hypothalamus but had no effect on hypothalamic mTOR phosphorylation. Feeding HFD but not CeA palmitate infusions reversed the hypothalamic Akt signaling response to CeA insulin. These data, which show the independence of Akt and mTOR signaling responses to insulin in the amygdala and the effect of insulin signaling in the CeA on hypothalamic Akt signaling, suggest that the amygdala might also have a significant role in regulating hypothalamic responses to dietary fat.
胰岛素注射到杏仁中央核（CeA）会抑制摄食，但在高脂饮食喂养时，这种反应很快就会消失。本手稿中描述的研究旨在确定这种胰岛素抵抗发展的潜在机制。高脂饮食（HFD）诱导 PKCθ 激活并阻断 CeA 胰岛素注射后 Akt 但不 mTOR 磷酸化的刺激。将棕榈酸输注到 CeA 具有与 HFD 对杏仁核中 PKCθ 表达和胰岛素信号相同的作用。CeA 胰岛素也诱导下丘脑 Akt 磷酸化增加，但对下丘脑 mTOR 磷酸化没有影响。喂养 HFD 而不是 CeA 棕榈酸输注逆转了 CeA 胰岛素对下丘脑 Akt 信号的反应。这些数据表明，Akt 和 mTOR 信号对胰岛素在杏仁核中的反应是独立的，以及 CeA 中的胰岛素信号对下丘脑 Akt 信号的影响，表明杏仁核可能在调节对膳食脂肪的下丘脑反应方面也具有重要作用。
