Ventral frontal satiation-mediated responses to food aromas in obese and normal-weight women

BACKGROUND: Sensory properties of foods promote and guide consumption in hunger states, whereas satiation should dampen the sensory activation of ingestive behaviors. Such activation may be disordered in obese individuals. OBJECTIVE: Using functional magnetic resonance imaging (fMRI), we studied regional brain responses to food odor stimulation in the sated state in obese and normal-weight individuals targeting ventral frontal regions known to be involved in coding for stimulus reward value. DESIGN: Forty-eight women (25 normal weight; 23 obese) participated in a 2-day (fed compared with fasting) fMRI study while smelling odors of 2 foods and an inedible, nonfood object. Analyses were conducted to permit an examination of both general and sensory-specific satiation (satiation effects specific to a given food). RESULTS: Normal-weight subjects showed significant blood oxygen level-dependent responses in the ventromedial prefrontal cortex (vmPFC) to food aromas compared with responses induced by the odor of an inedible object. Normal-weight subjects also showed general (but not sensory-specific) satiation effects in both the vmPFC and orbitofrontal cortex. Obese subjects showed no differential response to the aromas of food and the inedible object when fasting. Within- and between-group differences in satiation were driven largely by changes in the response to the odor of the inedible stimulus. Responses to food aromas in the obese correlated with trait negative urgency, the tendency toward negative affect-provoked impulsivity. CONCLUSIONS: Ventral frontal signaling of reward value may be disordered in obesity, with negative urgency heightening responses to food aromas. The observed nature of responses to food and nonfood stimuli suggests that future research should independently quantify each to fully understand brain reward signaling in obesity

Resistance of tomato strains to the moth Tuta absoluta imparted by allelochemicals and trichome density Resistência de linhagens de tomateiro à traça Tuta absoluta, relacionada a aleloquímicos e à densidade de tricomas

We examined the resistance of improved tomato strains rich in 2-tridecanone (2-TD), zingiberene (ZGB) and acyl sugars (AA) to the tomato moth, Tuta absoluta. We also studied whether selection for strains with higher densities of glandular trichomes, and thus presumably strains with higher concentrations of 2-tridecanone, was effective in promoting greater resistance to the moth. The TOM-584 and TOM-679 strains were used as susceptible controls, which have normal concentrations of the three allelochemicals. The improved strain TOM-687, which has a high AA content, has a widely documented resistance and was used as a standard resistant strain. The wild strain PI134417, which is resistant by means of its high 2-TD content, was also used as a standard resistant strain. The experiment was installed in a greenhouse with a completely randomized design. The wild strain PI 134417 was confirmed as being highly resistant. TOM-622 (rich in 2-TD), ZGB-703 (rich in ZGB), and TOM-687 (rich in AA) showed significant reductions in the oviposition rate of the tomato moth, damage to the plants, injury to the leaflets, and the percentage of leaflets attacked in comparison with the control strains (TOM-584 and TOM-679). The levels of resistance to the moth for the TOM-622, ZGB-703, and TOM-687 strains were similar. In general, the genotypes with higher densities of glandular trichomes had greater resistance than the susceptible controls, with the strain BPX-367D-238-02 being particularly notable in its resistance.<br>Comparou-se a efetividade de linhagens melhoradas de tomateiro, ricas em 2-tridecanona (2-TD), zingibereno (ZGB) e acilaçúcares (AA), em relação aos níveis de resistência à traça-do-tomateiro Tuta absoluta. Verificaram-se, também, se linhagens selecionadas para maiores densidades de tricomas glandulares, presumivelmente com maiores níveis de 2-tridecanona, são efetivas em promover maior resistência à traça. Como testemunhas suscetíveis foram utilizadas as linhagens TOM-584 e TOM-679, com nível normal dos três aleloquímicos. A linhagem melhorada TOM-687 (com alto teor de AA) foi utilizada como linhagem resistente padrão, por ter sua resistência amplamente documentada, juntamente com o também resistente acesso selvagem PI134417 (com alto teor de 2-TD). O experimento foi instalado em casa de vegetação, em delineamento inteiramente casualizado. O acesso selvagem PI 134417 confirmou-se como altamente resistente. TOM-622 (rica em 2-TD), ZGB-703 (rica em ZGB) e TOM-687 apresentaram diminuições significativas na ovoposição da traça-do-tomateiro, bem como no dano geral na planta, lesão nos folíolos e porcentagem de folíolos atacados, comparadas às testemunhas TOM-584 e TOM-679. Os níveis de resistência à traça em TOM-622, ZGB-703 e TOM-687 foram similares entre si. Em geral, os genótipos selecionados com maiores densidades de tricomas glandulares apresentaram níveis de resistência também superiores aos das testemunhas suscetíveis, destacando entre eles o tratamento BPX-367D-238-02