TY - JOUR T1 - Ghrelin Enhances Olfactory Sensitivity and Exploratory Sniffing in Rodents and Humans JF - The Journal of Neuroscience JO - J. Neurosci. SP - 5841 LP - 5846 DO - 10.1523/JNEUROSCI.5680-10.2011 VL - 31 IS - 15 AU - Jenny Tong AU - Erica Mannea AU - Pascaline Aimé AU - Paul T. Pfluger AU - Chun-Xia Yi AU - Tamara R. Castaneda AU - Harold W. Davis AU - Xueying Ren AU - Sarah Pixley AU - Stephen Benoit AU - Karyne Julliard AU - Stephen C. Woods AU - Tamas L. Horvath AU - Mark M. Sleeman AU - David D'Alessio AU - Silvana Obici AU - Robert Frank AU - Matthias H. Tschöp Y1 - 2011/04/13 UR - http://www.jneurosci.org/content/31/15/5841.abstract N2 - Olfaction is an integral part of feeding providing predictive cues that anticipate ingestion. Although olfactory function is modulated by factors such as prolonged fasting, the underlying neural mechanisms remain poorly understood. We recently identified ghrelin receptors in olfactory circuits in the brain. We therefore investigated the role of the appetite-stimulating hormone ghrelin in olfactory processing in rodents and humans, testing the hypothesis that ghrelin lowers olfactory detection thresholds and enhances exploratory sniffing, both being related to food seeking. In rats, intracerebroventricular ghrelin decreased odor detection thresholds and increased sniffing frequency. In humans, systemic ghrelin infusions significantly enhanced sniff magnitudes in response to both food and nonfood odorants and air in comparison to control saline infusions but did not affect the pleasantness ratings of odors. This is consistent with a specific effect on odor detection and not the hedonic value of odors. Collectively, our findings indicate that ghrelin stimulates exploratory sniffing and increases olfactory sensitivity, presumably enhancing the ability to locate, identify, and select foods. This novel role is consistent with ghrelin's overall function as a signal amplifier at the molecular interface between environmental and nutritional cues and neuroendocrine circuits controlling energy homeostasis. ER -