title: Effects of Escitalopram on a Rat Model of Persistent Stress-Altered Hedonic Activities: Towards a New Understanding of Stress and Depression.
abstract: Chronic mild stress (CMS) paradigm is a model to simulate clinical depression induced by long-term environmental stress. The present study investigated the effects of escitalopram, a specific serotonin reuptake inhibitor (SSRI), on depression-like activities in adult (18 week-old) Sprague-Dawley (SD) rats that underwent a total 8-week CMS. Body weight, locomotor activity and sucrose consumption of the rats were measured under CMS paradigm and following escitalopram treatment. The plasma level of corticosterone was also measured at the end of the experiment. Our results revealed that the CMS program reduced the body weight, but not the locomotor activity of the rats. Adult SD rats consumed less sucrose solution under CMS. However, chronic escitalopram regime (10 mg/kg/day for 4 weeks) appeared not helpful in reversing this CMS effect and, if any, the drug exaggerated anxiety profile of the animals. Unexpectedly, the stressed rats exhibited higher sucrose consumption than non-stressed rats after receiving repeated saline injections. Further, the stressed rats were found to have a higher plasma level of corticosterone after escitalopram treatment. Our results provide an example of the possibility that previously stressed individuals may develop an anti-depression ability that lessens the benefits of intervention with antidepressants. Finally, a separate group of rats that entered the CMS program at 10 week-old were used to examine possible effects of aging to interpret the stress coping ability observed in the 18 week-old rats. The younger rats developed less anti-anhedonia effects under repeated saline injections. The data of the present study provide a different perspective on stress-induced depression and possible interaction with antidepressants.
authors.affiliation: Department of Psychiatry, Taoyuan Armed Forces General Hospital, Taoyuan 32551, Taiwan, Republic of China.
authors.forename: Szu-Nian
authors.initials: SN
authors.lastname: Yang
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 11490, Taiwan, Republic of China.
authors.forename: Ying-Hsiu
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Division of Medical Research & Education, Cheng Hsin General Hospital, Taipei 11220, Taiwan, Republic of China.
authors.forename: Che-Se
authors.initials: CS
authors.lastname: Tung
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 11490, Taiwan, Republic of China.
authors.forename: Chih-Yuan
authors.initials: CY
authors.lastname: Ko
authors.affiliation: Department of Physiology and Biophysics, National Defense Medical Center, Taipei 11490, Taiwan, Republic of China.|Department of Psychiatry, Tri-Service General Hospital, Taipei 11490, Taiwan, Republic of China.
authors.forename: Yia-Ping
authors.initials: YP
authors.lastname: Liu
mesh_terms: D000367:Age Factors; D000818:Animals; D018687:Antidepressive Agents, Second-Generation / Q000494:pharmacology*; D015283:Citalopram / Q000494:pharmacology* / Q000627:therapeutic use; D003345:Corticosterone / Q000097:blood; D003863:Depression / Q000188:drug therapy*; D004195:Disease Models, Animal; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D013315:Stress, Psychological / Q000523:psychology*
chemical_list: D018687:Antidepressive Agents, Second-Generation; D015283:Citalopram; D003345:Corticosterone; D017367:Selective Serotonin Reuptake Inhibitors