Effects of a high-fat-diet supplemented with probiotics and ω3-fatty acids on appetite regulatory neuropeptides and neurotransmitters in a pig model

The pig is a valuable animal model to study obesity in humans due to the physiological similarity between humans and pigs in terms of digestive and associated metabolic processes. The dietary use of vegetal protein, probiotics and omega-3 fatty acids is recommended to control weight gain and to fight obesity-associated metabolic disorders. Likewise, there are recent reports on their beneficial effects on brain functions. The hypothalamus is the central part of the brain that regulates food intake by means of the production of food intake-regulatory hypothalamic neuropeptides, as neuropeptide Y (NPY), orexin A and pro-opiomelanocortin (POMC), and neurotransmitters, such as dopamine and serotonin. Other mesolimbic areas, such as the hippocampus, are also involved in the control of food intake. In this study, the effect of a high fat diet (HFD) alone or supplemented with these additives on brain neuropeptides and neurotransmitters was assessed in forty-three young pigs fed for 10 weeks with a control diet (T1), a high fat diet (HFD, T2), and HFD with vegetal protein supplemented with Bifidobacterium breve CECT8242 alone (T3) or in combination with omega-3 fatty acids (T4). A HFD provoked changes in regulatory neuropeptides and 3,4-dihydroxyphenylacetic acid (DOPAC) in the hypothalamus and alterations mostly in the dopaminergic system in the ventral hippocampus. Supplementation of the HFD with B. breve CECT8242, especially in combination with omega-3 fatty acids, was able to partially reverse the effects of HFD. Correlations between productive and neurochemical parameters supported these findings. These results confirm that pigs are an appropriate animal model alternative to rodents for the study of the effects of HFD on weight gain and obesity. Furthermore, they indicate the potential benefits of probiotics and omega-3 fatty acids on brain function.