Activation of physiological stress responses by a natural reward: Novel vs. repeated sucrose intake.
Pharmacological rewards, such as drugs of abuse, evoke physiological stress responses, including increased heart rate and blood pressure, and activation of the hypothalamic-pituitary-adrenal (HPA) axis. It is not clear to what extent the natural reward of palatable foods elicits similar physiological responses. In order to address this question, HPA axis hormones, heart rate, blood pressure and brain pCREB immunolabeling were assessed following novel and repeated sucrose exposure. Briefly, adult, male rats with ad libitum food and water were given either a single (day 1) or repeated (twice-daily for 14 days) brief (up to 30 min) exposure to a second drink bottle containing 4 ml of 30% sucrose drink vs. water (as a control for bottle presentation). Sucrose-fed rats drank more than water-fed on all days of exposure, as expected. On day 1 of exposure, heart rate, blood pressure, plasma corticosterone, and locomotion were markedly increased by presentation of the second drink bottle regardless of drink type. After repeated exposure (day 14), these responses habituated to similar extents regardless of drink type and pCREB immunolabeling in the hypothalamic paraventricular nucleus (PVN) also did not vary with drink type, whereas basolateral amygdala pCREB was increased by sucrose intake. Taken together, these data suggest that while sucrose is highly palatable, physiological stress responses were evoked principally by the drink presentation itself (e.g., an unfamiliar intervention by the investigators), as opposed to the palatability of the offered drink.
Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati School of Medicine, Cincinnati, OH, 45237, USA; Neuroscience Graduate Program, University of Cincinnati School of Medicine, Cincinnati, OH, 45237, USA.
Ann E
AE
Egan
Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati School of Medicine, Cincinnati, OH, 45237, USA. Electronic address: yvonne.ulrich-lai@uc.edu.
Yvonne M
YM
Ulrich-Lai
D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D050882:CREB-Binding Protein / Q000378:metabolism; D005518:Food Preferences / Q000502:physiology*; D005938:Glucocorticoids / Q000378:metabolism; D006339:Heart Rate / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000502:physiology; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology; D051381:Rats; D020318:Rats, Long-Evans; D012201:Reward; D013312:Stress, Physiological / Q000502:physiology*; D013395:Sucrose / Q000008:administration & dosage*; D013549:Sweetening Agents / Q000008:administration & dosage*; D013686:Telemetry; D013997:Time Factors
D005938:Glucocorticoids; D013549:Sweetening Agents; D013395:Sucrose; D000324:Adrenocorticotropic Hormone; D050882:CREB-Binding Protein
Cardiovascular; Glucocorticoids; Novelty; Palatable food; Reward; pCREB