Stressor-induced alterations in serotonergic activity in an animal model of depression

THE present study examined the effect of two neurogenic stressors (air puff and restraint) and a metabolic stressor (lipopolysaccharide; LPS 100 mu g/ kg, i.p.) on accumbal serotonergic neurotransmission in the olfactory bulbe ctomized (OB) rat model of depression. Both air puff and restraint stress c aused greater increases in accumbal 5-HIAA in OB than in sham-operated rats . In contrast, bulbectomy resulted in a blunted serotonergic response to a challenge with LPS (a metabolic stressor). In addition, OB rats displayed s ignificantly lower basal levels of 5-HIAA than sham-opera counterparts, a f inding consistent with previous reports of the OB rat being a model of hypo serotonergic depression. The relevance of these findings to stressor-provok ed depressive-like behaviors in the OB rat are discussed. (C) 1999 Lippinco tt Williams & Wilkins.