title: The Anxiolytic and Antidepressant-like Effects of Testosterone and Estrogen in Gonadectomized Male Rats.
abstract: BACKGROUND
  While the influence of testosterone levels on vulnerability to affective disorders is not straightforward, research suggests this hormone may confer some degree of resiliency in men. We recently demonstrated a role for the dentate gyrus in mediating testosterone's protective effects on depressive-like behavior in gonadectomized male rats. Here, testosterone may exert its effects through androgen receptor-mediated mechanisms or via local aromatization to estradiol.
  
  
  METHODS
  Gonadectomized male rats were implanted with a placebo, testosterone, or estradiol pellet, and subsequent protective anxiolytic- and antidepressant-like effects of testosterone and its aromatized metabolite, estradiol, were then investigated in the open field and sucrose preference tests, respectively. Moreover, their influence on gene expression in the hippocampus was analyzed by genome-wide complementary DNA microarray analysis. Finally, the contribution of testosterone's aromatization within the dentate gyrus was assessed by local infusion of the aromatase inhibitor fadrozole, whose efficacy was confirmed by liquid chromatography-tandem mass spectrometry.
  
  
  RESULTS
  Both hormones had antidepressant-like effects associated with a substantial overlap in transcriptional regulation, particularly in synaptic plasticity- and mitogen-activated protein kinase pathway-related genes. Further, chronic aromatase inhibition within the dentate gyrus blocked the protective effects of testosterone.
  
  
  CONCLUSIONS
  Both testosterone and estradiol exhibit anxiolytic- and antidepressant-like effects in gonadectomized male rats, while similarly regulating critical mediators of these behaviors, suggesting common underlying mechanisms. Accordingly, we demonstrated that testosterone's protective effects are mediated, in part, by its aromatization in the dentate gyrus. These findings thus provide further insight into a role for estradiol in mediating the protective anxiolytic- and antidepressant-like effects of testosterone.
authors: Department of Biomedical Sciences, Program in Neurosciences.
authors: Nicole
authors: N
authors: Carrier
authors: Department of Biomedical Sciences, Program in Neurosciences.
authors: Samantha K
authors: SK
authors: Saland
authors: Department of Biomedical Sciences, Program in Neurosciences.
authors: Florian
authors: F
authors: Duclot
authors: Department of Biomedical Sciences, Program in Neurosciences; Translational Science Laboratory, College of Medicine, Florida State University; Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida.
authors: Huan
authors: H
authors: He
authors: Department of Biomedical Sciences, Program in Neurosciences; Translational Science Laboratory, College of Medicine, Florida State University.
authors: Roger
authors: R
authors: Mercer
authors: Department of Biomedical Sciences, Program in Neurosciences. Electronic address: Mohamed.Kabbaj@med.fsu.edu.
authors: Mohamed
authors: M
authors: Kabbaj
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage; D000928:Antidepressive Agents / Q000008:administration & dosage; D001007:Anxiety / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology*; D047072:Aromatase Inhibitors / Q000494:pharmacology; D002369:Castration; D003863:Depression / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology*; D004967:Estrogens / Q000008:administration & dosage / Q000502:physiology*; D017316:Fadrozole / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000008:administration & dosage / Q000378:metabolism / Q000502:physiology*
chemical_list: D014151:Anti-Anxiety Agents; D000928:Antidepressive Agents; D047072:Aromatase Inhibitors; D004967:Estrogens; D013739:Testosterone; D017316:Fadrozole
keywords: Anxiety; Aromatase; Depression; Estradiol; Hippocampus; Testosterone