Serotonin and suicidality: the impact of fluoxetine administration. II: Acute neurobiological effects.

Despite the demonstrated anti-depressant efficacy of the selective serotonin reuptake inhibitors (SSRIs), increased suicidal ideation and/or agitation have been reported in a small proportion of individuals receiving fluoxetine or other SSRIs. Part II of this review examines fluoxetine's acute effects on serotonergic functioning. Although acute fluoxetine administration produces a short-term compensatory decrease in the firing of 5-HT neurons, the neurobiological data reviewed suggests that this decrease probably does not lead to an over-compensatory net decrease in 5-HT functioning. The implications of fluoxetine's complex effects on the 5-HT systems are discussed with respect to clinical practices and future research.