title: A benzodiazepine impairs the neurogenic and behavioural effects of fluoxetine in a rodent model of chronic stress.
abstract: Antidepressant agents such as fluoxetine have been shown to produce neurogenic effects involving transcriptional and translational changes that direct molecular and cellular plasticity. These cellular and molecular events appear necessary to mediate the therapeutic effects of fluoxetine and may be generated through the ability for fluoxetine to regulate BDNF levels. Clinically, benzodiazepines are frequently used in combination with standard antidepressants both for initial treatment and maintenance therapy, especially when comorbid anxiety is present. However, very little is known regarding the consequence of combined treatment of benzodiazepines and antidepressant on the development of clinical effect. The current study therefore examined the effect of co-administration of fluoxetine and the benzodiazepine, diazepam, on hippocampal neurogenesis in the social isolation rodent model of chronic stress. We demonstrate that 9 weeks of social isolation induces a deficit in motivational behaviour with increased anxiety as well as impairment in hippocampal neurogenesis. This was parallelled by reduced BDNF levels in the hippocampus. While treatment with fluoxetine alone for 3 weeks restored anxiety behaviour as well as progenitor cell proliferation and the generation of new hippocampal neurons, this effect was prevented by co-administration with diazepam. This suggests that co-administering benzodiazepines with antidepressants could significantly delay or prevent the cellular and behavioural improvement needed by patients. These findings indicate the need for future clinical studies designed to investigate the combined effects of benzodiazepines and antidepressants in patients.
authors: Department of Pharmacology and Clinical Pharmacology, Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
authors: Yuhui
authors: Y
authors: Sun
authors: Jane
authors: J
authors: Evans
authors: Bruce
authors: B
authors: Russell
authors: Rob
authors: R
authors: Kydd
authors: Bronwen
authors: B
authors: Connor
mesh_terms: D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000627:therapeutic use*; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D003975:Diazepam / Q000494:pharmacology / Q000627:therapeutic use; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D005473:Fluoxetine / Q000627:therapeutic use*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D055495:Neurogenesis / Q000187:drug effects*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012934:Social Isolation / Q000523:psychology; D013315:Stress, Psychological / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology*; D013550:Swimming / Q000523:psychology; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors
chemical_list: D000928:Antidepressive Agents; D019208:Brain-Derived Neurotrophic Factor; D005473:Fluoxetine; D001569:Benzodiazepines; D010751:Phosphopyruvate Hydratase; D003975:Diazepam; D013936:Thymidine