Acute ingestion of lipids and alteration of cerebral perfusion in obese patients

Author(s)

Cristiane Maria Mártires de Lima

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2015-01-27

Examining board members

Julio Sérgio Marchini; Jacqueline Isaura Alvarez Leite; Sérgio Alberto Rupp de Paiva; Antonio Carlos dos Santos; Helio Vannucchi

• Advisor: Julio Sérgio Marchini

Abstract

Human obesity is characterized by body accumulation of white adipose tissue. The pathophysiology can not be explained only by an imbalance between energy intake and consumption. There are a number of genetic, humoral, environmental and behavioral factors interconnected contributing to a positive energy balance and subsequent weight gain. In the regulation of feeding behavior, peripheral and central nervous system interact through hunger and satiety signals triggered by nutrient intake and gastrointestinal peptides. However, little is known about the intake of isolated nutrients and their effects on the brain. Thus, our hypothesis is that lipid intake causes changes in brain activity related to obesity. Objectives: Identify which brain regions are functionally related to lipid intake. Compare cerebral perfusion of volunteers with and without obesity. Correlate changes in cerebral blood flow with body fat and serum glucose, triacylglycerols, insulin and leptin. Materials and Methods: A blind randomized clinical trial involving two groups of people. Ten women with obesity and ten without obesity were evaluated by clinical examination, indirect calorimetry, bioelectrical impedance analysis, laboratory tests (serum measurements of glucose, insulin, leptin and triacylglycerols) and Single-photon Emission Tomography of brain after ingestion of water and lipid solution, having been the volunteers controls of themselves. Results: The means (standard deviations) of body mass index of the groups with and without obesity were respectively 21 (1.7) and 35 (3) kg/m2. There were still differences between the groups in the following variables expressed in approximate values for mean (standard deviation): systolic blood pressure - 107 (13) x 118 (12) mm Hg, diastolic blood pressure - 64 (10) x 74 (8) mmHg, HDL cholesterol - 53 (13) x 39 (6) mg/dL, glucose in times 0 - 82 (8) x 90 (5) mg/dL and 120 minutes of oral glucose tolerance test - 84 (13) x 100 (18) mg/dL and body fat - 17 (5) 38 x (3) kg. In obese women, after ingestion of lipid solution, decreased perfusion in regions of frontal lobe, temporal lobe, insula, brain stem, cerebellum, thalamus, putamen, globus pallidus, hippocampus, parahippocampal gyrus and frontal operculum was observed. On the other hand, women without obesity after eating the same food challenge presented increased perfusion in anterior regions of frontal lobe and anterior cingulate. The alterations found do not seem to be related to lipid absorption. Discussion and conclusion: After intake of lipids in patients without obesity, it was observed increased cerebral perfusion in areas related to control of inappropriate impulses. In patients with obesity, was found decreased perfusion in regions involved in gustatory sensibility. Both mechanisms, poor control of inappropriate impulses and increased food intake due to reduced consummatory reward, alone or together, can result in inappropriate control of body weight and consequent obesity. (AU)

• FAPESP's process: 12/21626-2 - Acute intake of lipids and changes in cerebral perfusion in obese patients
• Grantee: Cristiane Maria Mártires de Lima
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)