Immediate Effects of Maternal Deprivation on the LHPA Axis of the Developing Rat: consequences of Desipramine and Fluoxetine Treatment
Numerous behavioral, endocrine and clinical studies have shown that physical and psychological stressors can profoundly alter an organism's growth and development. The stress limbic-hypothalamic-pituitary-adrenal (LHPA) axis and the serotonin (5-HT) system are two biological pathways implicated in anxiety and depression. Antidepressants are thought to function, in part, by acting upon these systems. In this study, we investigated the effects of the antidepressants, desipramine and fluoxetine, on the LHP A axis of maternally deprived rat pups. We hypothesized that desipramine, a tricyclic antidepressant and norepinephrine reuptake inhibitor, would blunt the LHPA response, while fluoxetine, a selective serotonin reuptake inhibitor, would have no significant effect. Animals were treated with vehicle, desipramine or fluoxetine for seven days prior to maternal deprivation. Corticosterone levels were used as a measure of LHPA activity, while weight and linear growth were used to determine the effects of the drugs on somatic growth. Our findings showed that desipramine was effective in preventing the stress-related corticosterone elevation of maternally deprived rat pups, but it also had a detrimental effect on the physical growth of the pups. Fluoxetine was neither effective in preventing the stress-related corticosterone elevation, nor did it have a significant detrimental effect on physical growth. The effects of the antidepressants on the corticosterone response of the maternally deprived rats indicates that the stress paradigm used is more closely linked to catecholaminergic than serotonergic mechanisms. Further studies, using longer durations of treatment, are needed to better determine the clinical applications of using antidepressants for the prevention of psycopathology.
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