title: Mice subjected to uncontrollable electric shocks show depression-like behaviors irrespective of their state of helplessness.
abstract: The unpredictable and inescapable electric shock-induced "learned helplessness" paradigm has long been used to produce an animal model of depression to identify the molecules associated with depressive symptoms or to assess the efficacy of pharmacological treatments for depression. After exposure to unpredictable and inescapable shocks (uncontrollable stress), most of mice showed defect in escape behavior in active avoidance test (learned helplessness, LH), while others did not (non-learned helplessness, NLH). Here, we investigated whether mice with LH or NLH exhibited depressive symptoms, including anhedonia, anxiety, and despair. We found that compared with control naïve mice, both uncontrollable shocks-induced LH and NLH mice showed increased anhedonia- and anxiety- but not despair-like behaviors. Notably, mice subjected to uncontrollable shocks showed similar behaviors, irrespective of whether they also showed LH or NLH. Furthermore, since both LH and NLH mice showed only anhedonia- and anxiety- but not despair-like behaviors, this model may be generally inadequate for classic depression-like behavior assessment. In conclusion, uncontrollable electric shock induces depression-like behavior, irrespective of the state of helplessness.
authors.affiliation: Department of Anatomy, College of Medicine, Korea University, Seoul, Republic of Korea. Electronic address: jinyea@korea.ac.kr.
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Anatomy, College of Medicine, Korea University, Seoul, Republic of Korea. Electronic address: soohyun86@korea.ac.kr.
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Yang
authors.affiliation: Division of International Studies, Korea University, Seoul, Republic of Korea. Electronic address: jennakwon95@gmail.com.
authors.forename: Jihyun
authors.initials: J
authors.lastname: Kwon
authors.affiliation: Department of Anatomy, College of Medicine, Korea University, Seoul, Republic of Korea. Electronic address: biocais@korea.ac.kr.
authors.forename: Hyun Woo
authors.initials: HW
authors.lastname: Lee
authors.affiliation: Department of Anatomy, College of Medicine, Korea University, Seoul, Republic of Korea. Electronic address: kimhyun@korea.ac.kr.
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
mesh_terms: D059445:Anhedonia; D000818:Animals; D001007:Anxiety / Q000209:etiology; D003863:Depression / Q000209:etiology; D019422:Dietary Sucrose; D004597:Electroshock / Q000009:adverse effects*; D005106:Exploratory Behavior; D005247:Feeding Behavior; D006380:Helplessness, Learned; D008297:Male; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D009043:Motor Activity; D011581:Psychological Tests; D012201:Reward
chemical_list: D019422:Dietary Sucrose
keywords: Active avoidance; Depression; Depression animal model; Electric foot shock; Learned helplessness