title: Impaired imprinting and social behaviors in chicks exposed to mifepristone, a glucocorticoid receptor antagonist, during the final week of embryogenesis.
abstract: The effects of glucocorticoid receptor dysfunction during embryogenesis on the imprinting abilities and social behaviors of hatchlings were examined using "fertile hen's egg-embryo-chick" system.
  
  
  RESULTS
  Of embryos treated with mifepristone (0.4μmol/egg) on day 14, over 75% hatched a day later than the controls (day 22) without external anomalies. The mifepristone-treated hatchlings were assayed for imprinting ability on post-hatching day 2 and for social behaviors on day 3. The findings were as follows: imprinting ability (expressed as preference score) was significantly lower in mifepristone-treated hatchlings than in controls (0.65±0.06 vs. 0.92±0.02, P<0.005). Aggregation tests to evaluate the speed (seconds) required for four chicks, individually isolated with cardboard dividers in a box, to form a group after removal of the barriers showed that aggregation was significantly slower in mifepristone-treated hatchlings than in controls (8.7±1.1 vs. 2.6±0.3, P<0.001). In belongingness tests to evaluate the speed (seconds) for a chick isolated at a corner to join a group of three chicks placed at the opposite corner, mifepristone-treated hatchlings took significantly longer than controls (4.5±0.4/40 cm vs. 2.4±0.08/40 cm, P<0.001). In vocalization tests, using a decibel meter to measure average decibel level/30s (chick vocalization), mifepristone-treated hatchlings had significantly weaker vocalizations than controls (14.2±1.9/30s vs. 26.4±1.3/30s P<0.001). In conclusion, glucocorticoid receptor dysfunction during the last week embryogenesis altered the programming of brain development, resulting in impaired behavioral activities in late life.
authors.affiliation: Department of Pharmacotherapeutics, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Shiwa-gun, Iwate 028-3694, Japan. Electronic address: hnishigo@ar.wakwak.com.
authors.forename: Hideo
authors.initials: H
authors.lastname: Nishigori
authors.affiliation: Department of Pharmacotherapeutics, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Shiwa-gun, Iwate 028-3694, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kagami
authors.affiliation: Department of Obstetrics, Tohoku University Hospital, Sendai, Miyagi 980-8575, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Nishigori
mesh_terms: D000374:Aggression / Q000187:drug effects; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000473:pathology; D002642:Chick Embryo; D005260:Female; D007173:Imprinting, Psychological / Q000187:drug effects*; D007859:Learning Disabilities / Q000209:etiology*; D015735:Mifepristone / Q000633:toxicity*; D009929:Organ Size / Q000187:drug effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced* / Q000503:physiopathology; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors*; D012920:Social Behavior Disorders / Q000209:etiology*; D014828:Vocalization, Animal / Q000187:drug effects / Q000502:physiology
chemical_list: D011965:Receptors, Glucocorticoid; D015735:Mifepristone
keywords: Chick embryo; Filial imprinting; Glucocorticoid; Mifepristone; Prenatal exposure; Social behavior