Can Plasma Level of 3-methoxy-4-hydroxyphenylglycol Predict the Response for Selective Serotonin Reuptake Inhibitor and Serotonin Noradrenaline Reuptake Inhibitor in Major Depressive Disorder?

Abstract

IntroductionDepression is a serious mental illness requiring treatment. Major depressive disorder (MDD) is a complex disorder confounded by many bio psychosocial factors. Treatment with selective serotonin reuptake inhibitors (SSRIs) or serotonin noradrenaline reuptake inhibitors (SNRIs) is useful for MDD. The treatment of MDD requires collaborative efforts and holistic approaches by healthcare providers, public health interventions, and a reform in policies as well as the allocation of resources for the effective management of individuals with MDD, especially those with geriatric depression [1,2].A major metabolite of noradrenaline, 3-methoxy-4-hydroxyphenylglycol (MHPG), passes the blood-brain barrier. It is thought that 30% to 60% of plasma MHPG originates in the brain. When administered to patients with MDD, some antidepressants increase plasma MHPG, whereas other antidepressants decrease or do not change the plasma MHPG level. We demonstrated that paroxetine, an SSRI, decreased plasma MHPG, and that the SNRI milnacipran increased plasma MHPG; we also reviewed the effects of several antidepressants on plasma MHPG levels [3][4][5][6][7][8][9]. We also found that plasma MHPG is useful for predicting relapse to a major depressive episode in MDD patients [8]. Another of our studies showed that switching from paroxetine to milnacipran did not alter plasma MHPG levels [9]. We conducted the present study to investigate whether MDD patients' responses to an SSRI and an SNRI can be predicted based on plasma MHPG. Patients and MethodsPatients (n=240) with MDD diagnosed based on DSM-IV-TR were enrolled. All participants were undergoing monotherapy with the SSRI paroxetine (n=81), duloxetine, a selective serotonin and norepinephrine reuptake inhibitor antidepressant (SSNRI) (n=49), the SNRI milnacipran (n=48), the SSRI fluvoxamine (n=63), or the SSRI escitalopram (n=27). Only benzodiazepines were permitted during the study period. The patients (102 males, 138 females) were 42 ± 19 years old (mean ± SD). The severity of each patient's depressive state was evaluated with the 17-item Hamilton Rating Scale for Depression (HAMD17). The end-point point of the present study was week 8.Patients whose HAMD17 scores had decreased by ≥50% at the study end-point were defined as responders; others were considered non-responders. Blood was drawn twice before and 8 weeks after the start of treatment. Plasma MHPG levels were measured using highperformance liquid chromatography (HPLC) with electrochemical detection according to the method reported by Minegishi and Ishizaki [10]. Briefly, the plasma was separated by centrifugation at 600 g at 4°C. Extraction was performed under a vacuum using Bond-Elut columns (Varian, Palo Alto, CA) pre packed with 100 mg of C18-bonded silica (40 μm) in a 1 mL capacity disposable syringe. The columns, which were inserted into a vacuum chamber connected to an aspirator, were prepared by washing with 1 mL methanol followed by 1 mL of water.After the addition of 50 μL of a solution of vanillyl alcohol (in...

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“…Altogether, this previous study helped to understand the fact that norepinephrine levels play an etiological role in mood disorders. These data revealed that depression exists in two forms-a norepinephrine depression, marked by low levels of MHPG 10 and another, a serotonin depression 11 marked by the high levels of MHPG.…”