Antidepressant treatment during social challenge prior to 1 year of age affects immune and endocrine responses in adult macaques

Abstract

Antidepressants are widely used in treating depression and other behavioral problems in children and adolescents. Little is known about the long-term effects of these agents, particularly on physiological systems. The effects of previous antidepressant treatment during a social challenge in 9-month-old rhesus monkeys ( Macaca mulatta) on their adult immune and endocrine responses were studied. Prior to the social challenge, the monkeys were reared either by their mother or in a peer group. Monkeys were treated with either a serotonergic agonist (fluoxetine), a noradrenergic agonist (desipramine), or saline during social separation. Non-separated, saline-treated monkeys served as control monkeys. In order to evaluate immune effects of early antidepressant treatment, adult monkeys were immunized with a novel antigen, tetanus toxoid. Blood samples were collected prior to and at 4–5-day intervals for 28 days after immunization. Plasma total immunoglobulins (IgG and IgM), complement levels (C3 and C4), tetanus antibody titers, and cortisol were assessed. Antibody levels were lowest in monkeys treated with antidepressants regardless of specific drug treatment or early rearing condition. Drug-treated subjects had elevated plasma immunoglobulins and complement protein levels. Cortisol was also highest in drug-treated subjects. These results should be considered when prescribing commonly used antidepressants for treatment of childhood disorders.