Gabriela Ribeiro - PhD Student at the Champalimaud Centre for the unknown
Gabriela is here today to tell us about her work involving the neuroscience of obesity.
Gabriela Ribeiro is a PhD Student here at the Champalimaud Centre for the Unknown. She has a degree in nutrition from the University of Porto and in 2012 she completed her Master’s thesis in a collaboration with the Neuropsychiatry Unit. This summer Gabriela joined the same unit as a full-time PhD student, under the supervision of Albino Oliveira Maia. She is funded by a fellowship from the University of Lisbon.
In November, Gabriela presented her work at the 20th Portuguese Obesity Congress (20º Congresso Português de Obesidade), organised by the Portuguese Society for the Study of Obesity (Sociedade Portuguesa para o Estudo da Obesidade) and was awarded the honourable mention prize within the category of Nutrition.
What is the focus of your work?
I work with Ana Fernandes, a postdoc in the lab, to study obesity and the regulation of feeding behaviour beyond homeostatic needs. We eat because we require energy, but also because we enjoy eating; because it is pleasurable. The pleasure, or food reward response, which is modulated by dopamine and some specific brain areas, can be reflected in dysfunctional eating patterns in some individuals, and is thought to contribute towards the development of obesity.
Why do humans even derive pleasure from eating?
From an evolutionary standpoint, this is a difficult question to answer. One frequently considered possibility is that, upon availability of rare energy-dense food sources, such as simple carbohydrates, this component of feeding regulation would encourage their consumption beyond immediate energy needs. According to this possibility, one can also consider that changes in our food environment have happened so quickly that we have become unable to deal with them. We crave high-calorie foods as if they are still difficult to find, when the reality is quite the opposite.
Specifically, what are you working on at the moment?
We are working with Durval Costa, from the Nuclear Medicine Department, to study dopamine D2 availability in severely obese patients, before and after weight-loss surgery. It is well-known that, in the long-term, most alternatives for treatment of obesity are not effective, with most patients regaining the weight they have lost. Weight-loss surgeries, such as gastric bypass, are the most effective long-term treatments for severely obese patients. So, what happens to a patient’s brain after surgery that makes him or her more likely to avoid the behaviours that lead to weight regain? We want to understand how the dopamine system is changed after gastric surgeries that radically change eating behaviour.
Why does any change at all happen in a patient’s brain when they undergo weight-loss surgery?
The stomach and other areas of the gut are highly connected with the brain! Several nerves and hormones underlie gut-brain communication, and the different types of weight-loss surgery affect these lines of communication in different ways. There are malabsorptive procedures, restrictive surgeries, ablative surgeries… we hope to help clarify the effects of these different surgical solutions on the brain.
And moving forward, what are the next steps with your work?
At the Neuropsychiatry Unit we are also working to study the postingestive mechanisms of food reward, beyond palatability and beyond taste. Food reward is modulated by palatability, but also by postingestive mechanisms associated with the caloric content of a nutrient. Ana Fernandes and my supervisor developed a paradigm to measure postingestive-dependent behaviours in healthy volunteers, that we are now applying in obese patients. Previously this has been poorly studied before in the field of human obesity, so I am very excited about this direction of our work.
Obesity is a major problem, and one which I have encountered frequently in my work as a clinical nutritionist. Understanding the behavioural and neurobiological aspects of this condition is key to developing more effective treatments. This is a field that, in general, needs to be explored a great deal more, and I am eager to offer my contribution!