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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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Related in: MedlinePlus

Behavioural observations performed during the conditioning sessions.Body postures (A) and behavioural activity (B) recorded during 30 min after a meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant differences between two treatments (P<0.05) are indicated with an asterisk.
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pone-0037968-g003: Behavioural observations performed during the conditioning sessions.Body postures (A) and behavioural activity (B) recorded during 30 min after a meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant differences between two treatments (P<0.05) are indicated with an asterisk.

Mentions: There was no difference in the general activity exhibited by the animals after they received the NaCl or the Glu treatments (P>0.05). After the LiCl reinforcement, the animals spent less time standing (NaCl: z = 2.76, P<0.016; Glu: z = 2.5, P<0.016) and more time lying (NaCl: z = 2.76, P<0.016; Glu: z = 2.67, P<0.016) than after the NaCl or the Glu reinforcements (Figure 3a). They also spent more time inactive (NaCl: z = 2.93, P<0.016; Glu: z = 2.85, P<0.016) and less time in exploratory and playing activities (bars-focused, chain-focused or trough-focused activities) than after the NaCl or the Glu treatments (Figure 3b). The animals also spent 2% of their time vomiting whereas this behaviour was not expressed after the NaCl or the Glu treatments. A total of 2.1±0.4 vomiting occurrences were observed during the 30 min following the LiCl injection, with the first occurrence being observed 11.5±1.2 min after the beginning of the injection.


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)

Behavioural observations performed during the conditioning sessions.Body postures (A) and behavioural activity (B) recorded during 30 min after a meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant differences between two treatments (P<0.05) are indicated with an asterisk.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0037968-g003: Behavioural observations performed during the conditioning sessions.Body postures (A) and behavioural activity (B) recorded during 30 min after a meal associated with NaCl, LiCl or Glucose (Glu) duodenal injection. Data are presented with means and standard errors. Significant differences between two treatments (P<0.05) are indicated with an asterisk.
Mentions: There was no difference in the general activity exhibited by the animals after they received the NaCl or the Glu treatments (P>0.05). After the LiCl reinforcement, the animals spent less time standing (NaCl: z = 2.76, P<0.016; Glu: z = 2.5, P<0.016) and more time lying (NaCl: z = 2.76, P<0.016; Glu: z = 2.67, P<0.016) than after the NaCl or the Glu reinforcements (Figure 3a). They also spent more time inactive (NaCl: z = 2.93, P<0.016; Glu: z = 2.85, P<0.016) and less time in exploratory and playing activities (bars-focused, chain-focused or trough-focused activities) than after the NaCl or the Glu treatments (Figure 3b). The animals also spent 2% of their time vomiting whereas this behaviour was not expressed after the NaCl or the Glu treatments. A total of 2.1±0.4 vomiting occurrences were observed during the 30 min following the LiCl injection, with the first occurrence being observed 11.5±1.2 min after the beginning of the injection.

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