DVS is the main metabolite of the antidepressant/anxiolytic medication Venlafaxine (Effexor). Like parent compound, DVS is an antidepressant inhibiting both serotonin (5-HT) and norepinephrine (NE) reuptake. However, no studies to date describe the in vivo potency of this drug on monoamines reuptake. Consequently, it appears essential to determine the potency of DVS in human subjects using a wide dose range in order to determine at which dose(s) it starts inhibiting 5-HT and NE reuptake. The investigators are interested in learning whether there is a gender difference in the dose of the study medication at which NE reuptake inhibition occurs.

Inclusion Criteria:

• Female subjects between 18 and 40 years of age, including those on oral contraceptive pills
• Male subjects between 18-40 years of age
• Written informed consent signed by the subject.

Exclusion Criteria:

• Life-time personal history of diagnosis of major depression according to the DSM-IV (American Psychiatry Association, 1994) using the MINI (Sheehan et al. 1998)
• Blood pressure greater than 140/90 and a pulse rate greater than 90bpm
• Evidence of significant physical illness contraindicating the use of DVS, found on physical or in the laboratory data obtained during the first week of the study
• Obvious mental retardation rendering the response to investigators unreliable
• Pregnancy, or absence of adequate contraceptive method.
• Concurrent use of psychotropic medication such as antipsychotics, mood stabilizers or regular use of benzodiazepines.
• Participation in a clinical trial within 30 days of entry into the current study
• Intolerance to Desvenlafaxine