title: Increase of glucocorticoids is not required for the acquisition, but hinders the extinction, of lithium-induced conditioned taste aversion.
abstract: Lithium chloride at doses sufficient to induce conditioned taste aversion (CTA) causes c-Fos expression in the paraventricular nucleus and increases the plasma level of corticosterone with activation of the hypothalamic-pituitary-adrenal axis. This study was conducted to define the role of glucocorticoid in the acquisition and extinction of lithium-induced CTA. In experiment 1, Sprague-Dawley rats received dexamethasone (2mg/kg) or RU486 (20mg/kg) immediately after 5% sucrose access, and then an intraperitoneal injection of isotonic lithium chloride (12ml/kg) was followed with 30min interval. Rats had either 1 or 7 days of recovery period before the daily sucrose drinking tests. In experiment 2, rats were conditioned with the sucrose-lithium pairing, and then received dexamethasone or vehicle at 30min before each drinking test. In experiment 3, adrenalectomized (ADX or ADX+B) rats were subjected to sucrose drinking tests after the sucrose-lithium pairing. Dexamethasone, but not RU486, pretreatment blunted the formation of lithium-induced CTA memory. Dexamethasone prior to each drinking test suppressed sucrose consumption and prolonged the extinction of lithium-induced CTA. Sucrose consumption was significantly suppressed not only in ADX+B rats but also in ADX rats during the first drinking session; however, a significant decrease was found only in ADX rats on the fourth drinking session. These results reveal that glucocorticoid is not a necessary component in the acquisition, but an important player in the extinction, of lithium-induced CTA, and suggest that a pulse increase of glucocorticoid may hinder the extinction memory formation of lithium-induced CTA.
authors.affiliation: Department of Family Practice and Community Health, Ajou University School of Medicine, Suwon 443 721, Republic of Korea.
authors.forename: Kyu-Nam
authors.initials: KN
authors.lastname: Kim
authors.affiliation: Department of Family Practice and Community Health, Ajou University School of Medicine, Suwon 443 721, Republic of Korea. Electronic address: lovesong@ajou.ac.kr.
authors.forename: Bom-Taeck
authors.initials: BT
authors.lastname: Kim
authors.affiliation: Department of Family Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Republic of Korea.
authors.forename: Young-Sang
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Dental Research Institute, Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul 110768, Republic of Korea.
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Dental Research Institute, Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul 110768, Republic of Korea. Electronic address: jwjahng@snu.ac.kr.
authors.forename: Jeong Won
authors.initials: JW
authors.lastname: Jahng
mesh_terms: D000315:Adrenalectomy; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects*; D003907:Dexamethasone / Q000494:pharmacology; D004326:Drinking; D005108:Extinction, Psychological / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology; D008094:Lithium / Q000494:pharmacology*; D018021:Lithium Chloride / Q000494:pharmacology; D008297:Male; D015735:Mifepristone / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000494:pharmacology; D013649:Taste / Q000187:drug effects* / Q000502:physiology
chemical_list: D005938:Glucocorticoids; D016760:Proto-Oncogene Proteins c-fos; D015735:Mifepristone; D013395:Sucrose; D003907:Dexamethasone; D008094:Lithium; D018021:Lithium Chloride
keywords: Conditioned taste aversion; Hypothalamic–pituitary–adrenal axis; Lithium chloride; c-Fos