Parabrachial coding of sapid sucrose: Relevance to reward and obesity

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Abstract

Cumulative evidence in rats suggests that the pontine parabrachial nuclei (PBN) are necessary for assigning hedonic value to taste stimuli. In a series of studies, our laboratory has investigated the parabrachial coding of sapid sucrose in normal and obese rats. First, using chronic microdialysis, we demonstrated that sucrose intake increases dopamine release in the nucleus accumbens, an effect that is dependent on oral stimulation and on concentration. The dopamine response was independent of the thalamocortical gustatory system but was blunted substantially by lesions of the PBN. Similar lesions of the PBN but not the thalamic taste relay diminished cFos activation in the nucleus accumbens caused by sucrose ingestion. Recent single-neuron recording studies have demonstrated that processing of sucrose-evoked activity in the PBN is altered in Otsuka Long Evans Tokushima Fatty (OLETF) rats, which develop obesity due to chronic overeating and express increased avidity to sweet. Compared with lean controls, taste neurons in OLETF rats had reduced overall sensitivity to sucrose and altered concentration responses, with decreased responses to lower concentrations and augmented responses to higher concentrations. The decreased sensitivity to sucrose was specific to NaCl-best neurons that also responded to sucrose, but the concentration effects were carried by the sucrose-specific neurons. Collectively, these findings support the hypothesis that the PBN enables taste stimuli to engage the reward system and, in doing so, influences food intake and body weight regulation. Obesity, in turn, may further alter the gustatory code via forebrain connections to the taste relays or hormonal changes consequent to weight gain.

Original languageEnglish (US)
Title of host publicationInternational Symposium on Olfaction and Taste
PublisherBlackwell Publishing Inc.
Pages347-364
Number of pages18
ISBN (Print)9781573317382
DOIs
Publication statusPublished - Jul 2009

Publication series

NameAnnals of the New York Academy of Sciences
Volume1170
ISSN (Print)0077-8923
ISSN (Electronic)1749-6632

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All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • History and Philosophy of Science

Cite this

Hajnal, A., Norgren, R., & Kovacs, P. (2009). Parabrachial coding of sapid sucrose: Relevance to reward and obesity. In International Symposium on Olfaction and Taste (pp. 347-364). (Annals of the New York Academy of Sciences; Vol. 1170). Blackwell Publishing Inc.. https://doi.org/10.1111/j.1749-6632.2009.03930.x