Endocrine Abstracts

We have a relatively poor understanding of how the brain regulates appetite or why it can fail to do so during the development of obesity. Furthermore, neuroactive drugs are being suggested as potential pharmaceutical treatments often without a clear understanding of their mode of action. Energy-sensing systems of the brainstem and hypothalamus must engage higher motivational systems in order to enable adaptive responses. This is an important area of research as higher cognitive functions, such as decision making and the motivation to eat, are major determinants for the control of appetite, particularly in humans.

An upturn in our ability to interrogate the functioning of the ‘black box’ was catalysed by the discovery of leptin and coincided with the development of techniques that allowed analysis of neuronal activity in the whole brain while maintaining adequate temporal and spatial resolution. These techniques include ex vivo histological analysis of inducible activity markers and in vivo functional magnetic resonance imaging (fMRI). Each technique has strengths and weaknesses, which will be discussed with particular reference to the study of appetite regulation. Examples will be provided of both generic and specific activity markers, as well as different modes fMRI such as blood oxygenation level-dependent (BOLD) and manganese-enhanced (MEMRI) contrasts.