Abstract
To examine the effect of age on adaptive changes induced by antidepressant treatment, the prolactin (PRL) response to the acute administration of the serotonin agonist 1-(m-trifluoromethylphenyl)piperazine (TFmPP) (10 mg/kg) was assessed in prepubertal and adult male rats following repeated treatment with saline or amitriptyline (10 mg/kg bid). TFmPP produced increases in PRL in both age groups regardless of pretreatment, but a significant enhancement of the PRL response to acute TFmPP after 10 days of amitriptyline treatment was observed only in the adult rats (135 vs. 10%). These findings suggest that juvenile animals may possess a reduced capacity to develop functional enhancement of certain 5-HT systems following repeated antidepressant administration. The mechanism underlying the changes in the amitriptyline-induced up-regulation of PRL secretion by 5-HT is not well understood. Since this is a single experiment using a nonselective antidepressant drug and a serotonin agonist of unknown specificity, this apparent developmental difference should be interpreted with some caution. Speculatively, though, such a developmental difference could underlie reduced antidepressant efficacy that has been observed in clinical studies of young depressed patients.
Get full access to this article
View all access options for this article.