title: Increased 5-HT2 receptor-mediated behavior 11 days after shock in learned helplessness rats.
abstract: In the learned helplessness procedure, rats can be differentiated into two distinct groups. Learned helplessness (LH) rats do not learn to escape a controllable shock while non-learned helplessness (NLH) rats learn this response. This deficit in performance in LH rats lasted for 11 days. In LH rats, pretreatment with acute desipramine (15 mg/kg i.p.) or chronic diazepam (0.95 mg/kg/day p.o. for 7 days) did not produce recovery from this deficit of performance, but pretreatment with chronic desipramine (17.7 mg/kg/day p.o. for 7 days) or chronic mianserin (6.1 mg/kg/day p.o. for 7 days) led to recovery. Before presentation of uncontrollable shock, there was no difference between LH and NLH rats, but 11 days after the shock, head shakes induced by (+/-)-1-(2,5-demethoxy-4-iodophenyl)-2-aminopropane (DOI) in LH rats was significantly more frequent than those in NLH and naive rats without change of [3H]ketanserin binding. The basal corticosterone level was higher in LH rats than in NLH rats. These findings suggest that the learned helplessness model is a reliable animal model of depression accompanied by 5-HT2 receptor hypersensitivity.
authors.affiliation: Department of Neuropsychiatry, Faculty of Medicine, Tokyo Medical and Dental University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nankai
authors.forename: S
authors.initials: S
authors.lastname: Yamada
authors.forename: K
authors.initials: K
authors.lastname: Muneoka
authors.forename: M
authors.initials: M
authors.lastname: Toru
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D003345:Corticosterone / Q000097:blood; D003891:Desipramine / Q000494:pharmacology; D004597:Electroshock; D006380:Helplessness, Learned; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
chemical_list: D011985:Receptors, Serotonin; D003891:Desipramine; D003345:Corticosterone