Escitalopram and NHT normalized stress-induced anhedonia and molecular neuroadaptations in a mouse model of depression

PLoS One. 2017 Nov 15;12(11):e0188043. doi: 10.1371/journal.pone.0188043. eCollection 2017.

Abstract

Anhedonia is defined as a diminished ability to obtain pleasure from otherwise positive stimuli. Anxiety and mood disorders have been previously associated with dysregulation of the reward system, with anhedonia as a core element of major depressive disorder (MDD). The aim of the present study was to investigate whether stress-induced anhedonia could be prevented by treatments with escitalopram or novel herbal treatment (NHT) in an animal model of depression. Unpredictable chronic mild stress (UCMS) was administered for 4 weeks on ICR outbred mice. Following stress exposure, animals were randomly assigned to pharmacological treatment groups (i.e., saline, escitalopram or NHT). Treatments were delivered for 3 weeks. Hedonic tone was examined via ethanol and sucrose preferences. Biological indices pertinent to MDD and anhedonia were assessed: namely, hippocampal brain-derived neurotrophic factor (BDNF) and striatal dopamine receptor D2 (Drd2) mRNA expression levels. The results indicate that the UCMS-induced reductions in ethanol or sucrose preferences were normalized by escitalopram or NHT. This implies a resemblance between sucrose and ethanol in their hedonic-eliciting property. On a neurobiological aspect, UCMS-induced reduction in hippocampal BDNF levels was normalized by escitalopram or NHT, while UCMS-induced reduction in striatal Drd2 mRNA levels was normalized solely by NHT. The results accentuate the association of stress and anhedonia, and pinpoint a distinct effect for NHT on striatal Drd2 expression.

MeSH terms

  • Anhedonia*
  • Animals
  • Antidepressive Agents, Second-Generation / pharmacology
  • Antidepressive Agents, Second-Generation / therapeutic use*
  • Brain-Derived Neurotrophic Factor / genetics
  • Citalopram / pharmacology
  • Citalopram / therapeutic use*
  • Depression / drug therapy*
  • Depression / psychology
  • Disease Models, Animal*
  • Herbal Medicine*
  • Hippocampus / drug effects
  • Hippocampus / metabolism
  • Male
  • Mice
  • Mice, Inbred ICR
  • RNA, Messenger / metabolism
  • Receptors, Dopamine D2 / genetics
  • Stress, Physiological*

Substances

  • Antidepressive Agents, Second-Generation
  • Brain-Derived Neurotrophic Factor
  • RNA, Messenger
  • Receptors, Dopamine D2
  • Citalopram

Grants and funding

Funding for this study was provided by the Israel Science Foundation (ISF, http://www.isf.org.il, Grant 738/11), by the National Institute for Psychobiology in Israel (NIPI, http://www.psychobiology.org.il, Grant 7-2011-12) and by the Open University of Israel research fund (http://www.openu.ac.il) (all funds received by R.D.); the ISF, NIPI and the Open University of Israel had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.