Effects of psychotropic drugs on nerve growth factor protein levels in the rat brain

Introduction: Psychotropic drugs exert their effects, in part, by increasing neurotrophin levels in the brain. Nerve growth factor (NGF) protein levels after treatment with only a limited number of psychotropics have been determined. The present study was designed in order to evaluate the effects of acute and chronic administration of different psychotropic drugs on NGF protein levels in five brain regions including frontal cortex, hippocampus, amygdala, olfactory bulb, and brain stem. Methods: Adult male Sprague-Dawley rats received acute or chronic (21 days) injections of desipramine, phenelzine, fluoxetine, chlordiazepoxide (10 mg/kg, each), haloperidol (1 mg/kg), and clozapine (20 mg/kg). Twentyfour hours after the last injection, NGF protein level was quantified in the dissected brain regions by using an ELISA kit. Results: Acute administration of these drugs did not affect NGF protein levels in the brain. Chronic injections of desipramine, phenelzine, fluoxetine, haloperidol, and clozapine led to the enhancement of NGF in the frontal cortex. Desipramine, fluoxetine, phenelzine and clozapine enhanced NGF in the hippocampus. In the olfactory bulb, desipramine and fluoxetine increased NGF, whereas, phenelzine and haloperidol reduced it. NGF levels in the amygdala and brain stem were not changed by any medication. Chronic administration of chlordiazepoxide did not affect NGF protein in the brain. Conclusion: Psychotropic drugs exert dissimilar effects on NGF protein levels in the brain. This might be indicative of their therapeutic properties and differential effects on cognitive function.