title: Single ketamine infusion in bipolar depression resistant to antidepressants: are neurotrophins involved?
abstract: OBJECTIVE
  We investigated serum brain-derived neurotrophin factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NTF3), neurotrophin-4 (NTF4) and the glial-derived neurotrophic factor (GDNF), in relation to ketamine efficacy, in bipolar depressed patients resistant to treatment with antidepressants.
  
  
  METHODS
  Twenty-five patients (4 male, 21 female), aged 27-67 years, with bipolar depression, receiving mood-stabilizing medications, were studied. Antidepressants were discontinued for at least 7 days before single intravenous ketamine infusion (0.5 mg/kg body weight). Response to ketamine was defined as ≥ 50% reduction on 17-item Hamilton Depression Rating Scale (HDRS) after 1 week, and remission as HDRS score ≤ 7. Serum BDNF, NGF, NTF3, NTF4 and GDNF levels were estimated by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  There were 13 ketamine responders and 12 non-responders. The remission was obtained in eight and 12 patients after seven and 14 days, respectively. At baseline, there were no differences between responders and non-responders in any of the neurotrophins. Serum BDNF was significantly reduced after 7 days in non-responders. Serum NGF, NT3, NT4 and GDNF did not significantly change.
  
  
  CONCLUSIONS
  The results confirm an antidepressant effect of ketamine infusion as an add-on to mood-stabilizing drugs in bipolar depression resistant to antidepressant treatment. They may also suggest a possible involvement of BDNF in this effect.
authors.affiliation: Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, Poland. rybakows@wlkp.top.pl
authors.forename: Janusz K
authors.initials: JK
authors.lastname: Rybakowski
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Permoda-Osip
authors.forename: Maria
authors.initials: M
authors.lastname: Skibinska
authors.forename: Rafal
authors.initials: R
authors.lastname: Adamski
authors.forename: Alicja
authors.initials: A
authors.lastname: Bartkowska-Sniatkowska
mesh_terms: D000328:Adult; D000368:Aged; D000928:Antidepressive Agents / Q000008:administration & dosage*; D015415:Biomarkers / Q000097:blood; D001714:Bipolar Disorder / Q000188:drug therapy* / Q000378:metabolism* / Q000523:psychology; D019208:Brain-Derived Neurotrophic Factor / Q000097:blood / Q000502:physiology*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007649:Ketamine / Q000008:administration & dosage* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000502:physiology*; D016896:Treatment Outcome
chemical_list: D000928:Antidepressive Agents; D015415:Biomarkers; D019208:Brain-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D007649:Ketamine; C579455:BDNF protein, human