title: Gastric bypass surgery alters behavioral and neural taste functions for sweet taste in obese rats.
abstract: Roux-en-Y gastric bypass surgery (GBS) is the most effective treatment for morbid obesity. GBS is a restrictive malabsorptive procedure, but many patients also report altered taste preferences. This study investigated the effects of GBS or a sham operation (SH) on body weight, glucose tolerance, and behavioral and neuronal taste functions in the obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats lacking CCK-1 receptors and lean controls (LETO). OLETF-GBS rats lost body weight (-26%) and demonstrated improved glucose tolerance. They also expressed a reduction in 24-h two-bottle preference for sucrose (0.3 and 1.0 M) and decreased 10-s lick responses for sucrose (0.3 through 1.5 M) compared with OLETF-SH or LETO-GBS. A similar effect was noted for other sweet compounds but not for salty, sour, or bitter tastants. In lean rats, GBS did not alter responses to any stimulus tested. Extracellular recordings from 170 taste-responsive neurons of the pontine parabrachial nucleus revealed a rightward shift in concentration responses to oral sucrose in obese compared with lean rats (OLETF-SH vs. LETO-SH): overall increased response magnitudes (above 0.9 M), and maximum responses occurring at higher concentrations (+0.46 M). These effects were reversed by GBS, and neural responses in OLETF-GBS were statistically not different from those in any LETO groups. These findings confirm obesity-related alterations in taste functions and demonstrate the ability of GBS to alleviate these impairments. Furthermore, the beneficial effects of GBS appear to be independent of CCK-1 receptor signaling. An understanding of the underlying mechanisms for reduced preferences for sweet taste could help in developing less invasive treatments for obesity.
authors.affiliation: Dept. of Neural and Behavioral Sciences, The Milton S. Hershey Medical Center, The Pennsylvania State Univ., Hershey, PA 17033, USA. ahajnal@psu.edu
authors.forename: Andras
authors.initials: A
authors.lastname: Hajnal
authors.forename: Peter
authors.initials: P
authors.lastname: Kovacs
authors.forename: Tamer
authors.initials: T
authors.lastname: Ahmed
authors.forename: Katia
authors.initials: K
authors.lastname: Meirelles
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lynch
authors.forename: Robert N
authors.initials: RN
authors.lastname: Cooney
mesh_terms: D000818:Animals; D001786:Blood Glucose; D005247:Feeding Behavior / Q000502:physiology*; D015390:Gastric Bypass; D005951:Glucose Tolerance Test; D008297:Male; D009765:Obesity / Q000378:metabolism* / Q000601:surgery; D051381:Rats; D020334:Rats, Inbred OLETF; D013395:Sucrose; D013549:Sweetening Agents / Q000378:metabolism; D013649:Taste / Q000502:physiology*; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D013549:Sweetening Agents; D013395:Sucrose