Increased KATP channel activity leads to potassium outflow from the neurons, resulting in hyperpolarization
of membrane potential. This effect, in turn, can lead to silencing of POMC neurons and consequent diminished α-MSH release even in the presence of elevated leptin levels. Because α-MSH is the critical activator of MC4 receptors that promote satiety, impaired release of this peptide, by default, will promote feeding. Glucose intolerance and insulin resistance are common symptoms of type 2 diabetes and are closely linked to body mass index (BMI). Yang et al. (2012) observed a discrepancy in the relationship between BMI and glucose intolerance in POMC-specific Tsc1 KO mice. They argue that specific activation selleck chemicals of KATP channels in POMC neurons may improve glucose metabolism, because a previous study described that hypothalamic activation of KATP channels can, under very specific circumstances, lead to enhanced glucose metabolism ( Pocai et al., 2005). However, studies PARP inhibitor have shown that there is positive interaction between POMC neuron activity and glucose metabolism regardless of feeding behavior and adiposity ( Berglund et al., 2012). Thus, more studies are needed to reconcile these differential effects.
Whether the observations of Yang et al. (2012) could lead to the development of successful strategies to interfere with age-associated metabolic impairments will be answered in the future. “
“When you look into a convex mirror, you will see yourself looking into the mirror (Figure 1A). You might pick up the mirror others and move it around your face. Then you will see yourself reflected at various angles under the control of your hand’s movement. Like the mirror reflecting us, we are endowed with the ability to monitor our own thoughts and cognition from
various aspects. This ability is termed metacognition (Flavell, 1979). For instance, if you are cramming for an upcoming history exam, you may decide to focus on the material that you feel you understand the least. Or when you are reading a difficult book, you may reread a paragraph if you feel you did not initially grasp its meaning, and in some cases you may look up background information in an encyclopedia. Metacognition is the process by which you make a judgment on the basis of introspection of your own cognitive state. In this way, metacognition allows you to assess and regulate the current state of your cognitive activity so that you can determine how to act in a given situation (Dunlosky and Metcalfe, 2009). Localization of metacognitive functioning in the human brain was attempted in a neuropsychological study of specific frontal lesions (Schnyer et al., 2004) and in an fMRI study of healthy subjects (Kikyo et al., 2002; Maril et al., 2003). Some frontal areas were found to be recruited when participants experienced a “feeling of knowing” what was to be recalled (Kikyo et al., 2002).