Presentation Details
| AChemS Undergrad Finalist: Palatability-Dependent Activation of Orexin Neurons in the Lateral Hypothalamus Kat Browning, Kathleen C.Maigler, Donald B.Katz. Brandeis University, Waltham, MA, USA |
Abstract
Orexin neurons are a distinct population in the lateral hypothalamus (LH) well characterized for their role in feeding and arousal, especially regarding palatable, high-calorie food. Prior work has demonstrated single-unit LH taste responses promptly reflect palatability; however, orexin neurons’ role in processing the hedonic value of taste is yet to be characterized, as the majority of work in orexin only includes high-value or hedonically positive stimuli. The present research examines cFos reactivity in orexin neurons in rats given intraoral taste solutions that span the palatability spectrum (either 0.3M sucrose, 5mM quinine, or water). Preliminary results indicate that sucrose-receiving animals show a higher percentage of cFos-positive orexin neurons than those receiving water or quinine, suggesting orexin neurons preferentially respond to palatable taste stimuli. To elucidate the role of palatability in driving this response, independent of caloric or post-ingestive feedback, a second experiment was conducted with sucrose made aversive via conditioned taste aversion (CTA), following pairing with 0.3M LiCl. If orexin neurons are palatability-responsive, we hypothesize that the CTA animals’ orexin response to sucrose will be significantly lower than in saline control as a result of the tastes’ inversion in palatability. These findings will directly implicate orexin neurons’ taste response as palatability-dependent units in the LH.
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