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Exposures to conditioned flavours with different hedonic values induce contrasted behavioural and brain responses in pigs.

Clouard C, Jouhanneau M, Meunier-Salaün MC, Malbert CH, Val-Laillet D - PLoS ONE (2012)

Bottom Line: Surprisingly, the F(NaCl) food was also preferred over the F(Glu) food during the first test only, suggesting that, while LiCl i.d. infusions led to a strong flavour aversion, glucose infusions failed to induce flavour preference.As for brain imaging results, exposure to aversive or less preferred flavours triggered global deactivation of the prefrontal cortex, specific activation of the posterior cingulate cortex, as well as asymmetric brain responses in the basal nuclei and the temporal gyrus.In conclusion, postingestive visceral stimuli can modulate the flavour/food hedonism and further feeding choices.

View Article: PubMed Central - PubMed

Affiliation: INRA, UR1341 ADNC (Alimentation & Adaptations Digestives, Nerveuses et Comportementales), Saint Gilles, France.

ABSTRACT
This study investigated the behavioural and brain responses towards conditioned flavours with different hedonic values in juvenile pigs. Twelve 30-kg pigs were given four three-day conditioning sessions: they received three different flavoured meals paired with intraduodenal (i.d.) infusions of 15% glucose (F(Glu)), lithium chloride (F(LiCl)), or saline (control treatment, F(NaCl)). One and five weeks later, the animals were subjected to three two-choice feeding tests without reinforcement to check the acquisition of a conditioned flavour preference or aversion. In between, the anaesthetised pigs were subjected to three (18)FDG PET brain imaging coupled with an olfactogustatory stimulation with the conditioned flavours. During conditioning, the pigs spent more time lying inactive, and investigated their environment less after the F(LiCl) than the F(NaCl) or F(Glu) meals. During the two-choice tests performed one and five weeks later, the F(NaCl) and F(Glu) foods were significantly preferred over the F(LICl) food even in the absence of i.d. infusions. Surprisingly, the F(NaCl) food was also preferred over the F(Glu) food during the first test only, suggesting that, while LiCl i.d. infusions led to a strong flavour aversion, glucose infusions failed to induce flavour preference. As for brain imaging results, exposure to aversive or less preferred flavours triggered global deactivation of the prefrontal cortex, specific activation of the posterior cingulate cortex, as well as asymmetric brain responses in the basal nuclei and the temporal gyrus. In conclusion, postingestive visceral stimuli can modulate the flavour/food hedonism and further feeding choices. Exposure to flavours with different hedonic values induced metabolism differences in neural circuits known to be involved in humans in the characterization of food palatability, feeding motivation, reward expectation, and more generally in the regulation of food intake.

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Quantity of food (g) consumed during the four conditioning sessions.During the conditioning period, the animals were given a 30-min flavoured meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant simple mean effects are indicated with asterisks and letters. An asterisk indicates a significant difference between two treatments during a single conditioning session (* P<0.05). Two different letters indicate a significant difference between two conditioning sessions for the same treatment (P<0.01).
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pone-0037968-g002: Quantity of food (g) consumed during the four conditioning sessions.During the conditioning period, the animals were given a 30-min flavoured meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant simple mean effects are indicated with asterisks and letters. An asterisk indicates a significant difference between two treatments during a single conditioning session (* P<0.05). Two different letters indicate a significant difference between two conditioning sessions for the same treatment (P<0.01).

Mentions: The food consumption data are presented in Figure 2. The two-way within subjects ANOVA showed no global effect of the treatment (F(2,20) = 1.82, P = 0.19), but a significant global effect of the conditioning session (F(3,30) = 6.32, P<0.01) in that the pigs consumed more food during the first session than during the fourth (P<0.05) session; other comparisons were not significantly different. There was also a significant session-treatment interaction (F(6,60) = 9.48, P<0.001). Simple mean effect tests revealed that the FLiCl food intake decreased over sessions in that the pigs consumed less of the FLiCl food during the third (P<0.01) and fourth (P<0.001) sessions than during the first session, and during the fourth session than during the second session (P<0.001). The pigs also consumed less of the FLiCl food than of the FNaCl food (P<0.05) during the third and fourth sessions, and than the FGlu food (P<0.05) during the fourth session only.


Exposures to conditioned flavours with different hedonic values induce contrasted behavioural and brain responses in pigs.

Clouard C, Jouhanneau M, Meunier-Salaün MC, Malbert CH, Val-Laillet D - PLoS ONE (2012)

Quantity of food (g) consumed during the four conditioning sessions.During the conditioning period, the animals were given a 30-min flavoured meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant simple mean effects are indicated with asterisks and letters. An asterisk indicates a significant difference between two treatments during a single conditioning session (* P<0.05). Two different letters indicate a significant difference between two conditioning sessions for the same treatment (P<0.01).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368353&req=5

pone-0037968-g002: Quantity of food (g) consumed during the four conditioning sessions.During the conditioning period, the animals were given a 30-min flavoured meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant simple mean effects are indicated with asterisks and letters. An asterisk indicates a significant difference between two treatments during a single conditioning session (* P<0.05). Two different letters indicate a significant difference between two conditioning sessions for the same treatment (P<0.01).
Mentions: The food consumption data are presented in Figure 2. The two-way within subjects ANOVA showed no global effect of the treatment (F(2,20) = 1.82, P = 0.19), but a significant global effect of the conditioning session (F(3,30) = 6.32, P<0.01) in that the pigs consumed more food during the first session than during the fourth (P<0.05) session; other comparisons were not significantly different. There was also a significant session-treatment interaction (F(6,60) = 9.48, P<0.001). Simple mean effect tests revealed that the FLiCl food intake decreased over sessions in that the pigs consumed less of the FLiCl food during the third (P<0.01) and fourth (P<0.001) sessions than during the first session, and during the fourth session than during the second session (P<0.001). The pigs also consumed less of the FLiCl food than of the FNaCl food (P<0.05) during the third and fourth sessions, and than the FGlu food (P<0.05) during the fourth session only.

Bottom Line: Surprisingly, the F(NaCl) food was also preferred over the F(Glu) food during the first test only, suggesting that, while LiCl i.d. infusions led to a strong flavour aversion, glucose infusions failed to induce flavour preference.As for brain imaging results, exposure to aversive or less preferred flavours triggered global deactivation of the prefrontal cortex, specific activation of the posterior cingulate cortex, as well as asymmetric brain responses in the basal nuclei and the temporal gyrus.In conclusion, postingestive visceral stimuli can modulate the flavour/food hedonism and further feeding choices.

View Article: PubMed Central - PubMed

Affiliation: INRA, UR1341 ADNC (Alimentation & Adaptations Digestives, Nerveuses et Comportementales), Saint Gilles, France.

ABSTRACT
This study investigated the behavioural and brain responses towards conditioned flavours with different hedonic values in juvenile pigs. Twelve 30-kg pigs were given four three-day conditioning sessions: they received three different flavoured meals paired with intraduodenal (i.d.) infusions of 15% glucose (F(Glu)), lithium chloride (F(LiCl)), or saline (control treatment, F(NaCl)). One and five weeks later, the animals were subjected to three two-choice feeding tests without reinforcement to check the acquisition of a conditioned flavour preference or aversion. In between, the anaesthetised pigs were subjected to three (18)FDG PET brain imaging coupled with an olfactogustatory stimulation with the conditioned flavours. During conditioning, the pigs spent more time lying inactive, and investigated their environment less after the F(LiCl) than the F(NaCl) or F(Glu) meals. During the two-choice tests performed one and five weeks later, the F(NaCl) and F(Glu) foods were significantly preferred over the F(LICl) food even in the absence of i.d. infusions. Surprisingly, the F(NaCl) food was also preferred over the F(Glu) food during the first test only, suggesting that, while LiCl i.d. infusions led to a strong flavour aversion, glucose infusions failed to induce flavour preference. As for brain imaging results, exposure to aversive or less preferred flavours triggered global deactivation of the prefrontal cortex, specific activation of the posterior cingulate cortex, as well as asymmetric brain responses in the basal nuclei and the temporal gyrus. In conclusion, postingestive visceral stimuli can modulate the flavour/food hedonism and further feeding choices. Exposure to flavours with different hedonic values induced metabolism differences in neural circuits known to be involved in humans in the characterization of food palatability, feeding motivation, reward expectation, and more generally in the regulation of food intake.

Show MeSH
Related in: MedlinePlus