title: Electroretinographic modifications induced by agomelatine: a novel avenue to the understanding of the claimed antidepressant effect of the drug?
abstract: BACKGROUND
  Agomelatine, the first melatonergic antidepressant, has been postulated to enhance the dopaminergic activity at the central nervous system by 5-hydroxytryptamine receptor type 2C (5-HT2C) antagonism, yet the impact of melatonergic agonism on this pathway is unclear. Previous studies employing simplified, yet reliable, proxy (retinal) measures of the central nervous system dopaminergic activity, namely the standard electroretinogram (ERG) technique, suggested a reduction of the dopaminergic activity of the main ERG parameter, the b-wave, by pure melatonin, notably a hormone devoid of any antidepressant activity. Therefore, the antidepressant effects of the melatonergic antidepressant drug agomelatine should be reflected by a differential b-wave trend at ERG versus the effect exerted by pure melatonin, which was eventually found to be due to a contrasting effect on central dopaminergic transmission between the two drugs.
  
  
  OBJECTIVE
  The aim of the present preliminary ERG study carried out on healthy volunteers (n=23) receiving agomelatine was to explore the impact of this antidepressant drug on b-wave amplitude and latency of cones in daylight conditions using standard ERG.
  
  
  RESULTS
  As postulated, agomelatine induced an enhancement of retinal dopaminergic activity, in contrast to what has been previously documented for melatonin.
  
  
  CONCLUSIONS
  Given the limits of this explorative study, especially the lack of a control group and that of a luminance response function to measure retinal sensitivity, further studies in clinical samples are recommended to allow more tenable conclusions about the potential role of ERG in discriminating between 5-HT antagonism and melatonergic (MT) agonism in relationship to the claimed antidepressant effect of agomelatine.
authors.affiliation: Department of Educative Science, University of Catania, Catania, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Fornaro
authors.affiliation: Department of Neurology, San Paolo Hospital, Savona, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Bandini
authors.affiliation: Department of Ophthalmology, University of Pisa, Pisa, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Cestari
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics - Section of Neurology, University of Genoa, Genoa, Italy.
authors.forename: Christian
authors.initials: C
authors.lastname: Cordano
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics - Section of Neurology, University of Genoa, Genoa, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Ogliastro
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics - Section of Neurology, University of Genoa, Genoa, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Albano
authors.affiliation: National Health Service, Department of Mental Health, Psychiatric Service of Diagnosis and Treatment, Hospital G. Mazzini, ASL 4, Teramo, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: De Berardis
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics - Section of Psychiatry, University of Genoa, Genoa, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Martino
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics - Section of Psychiatry, University of Genoa, Genoa, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Escelsior
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics - Section of Psychiatry, University of Genoa, Genoa, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Rocchi
authors.affiliation: Department of Neurosciences, Ophthalmology and Genetics - Section of Psychiatry, University of Genoa, Genoa, Italy.
authors.forename: Pantaleo
authors.initials: P
authors.lastname: Fornaro
authors.affiliation: Department of Educative Science, University of Catania, Catania, Italy.
authors.forename: Concetta
authors.initials: C
authors.lastname: De Pasquale
keywords: 5-HT2C; ERG; dopamine; electroretinogram