Lateral hypothalamus dopamine D1-like receptors and glucose-conditioned flavor preferences in rats

This study examined the role of dopamine D1-like receptor transmission in the lateral hypothalamus (LH) in flavor preference learning induced by intragastric (IG) infusions of glucose. Rats fitted with gastric catheters were injected daily in the LH with either saline or SCH23390 (12 nmol/brain), 10 min prior to training sessions with a flavor (CS+) paired with IG infusions of 8% glucose and a different flavor (CS−) paired with IG water infusions. In a post-training two-bottle test, SCH-treated rats preferred the CS+ to the CS− although their preference was weaker than that of the Control rats (61% vs. 87%). The same dose of SCH23390 reduced CS+ intake of the Control rats in a subsequent test but did not suppress their CS+ preference (90%). These results show that D1-like receptor activation in the lateral hypothalamus modulates the acquisition, but not the expression of flavor preference learning induced by the post-oral reinforcing properties of glucose.