Dynamic changes in AP-1 transcription factor DNA binding activity in rat brain following administration of antidepressant amitriptyline and brain-derived neurotrophic factor.

The present study was undertaken to examine the effects of the antidepressant, amitriptyline, and brain-derived neurotrophic factor (BDNF) on activator protein-1 (AP-1) DNA binding activity in the rat brain. Acute administration of amitriptyline (5 or 10 mg/kg) initially increased but then decreased AP-1 DNA binding activity in the rat frontal cortex and hippocampus. Chronic administration of amitriptyline (5 or 10 mg/kg, once daily for 3 weeks) initially decreased AP-1 DNA binding activity but ultimately resulted in its persistent elevation in the rat frontal cortex. In contrast, the chronic administration of amitriptyline did not affect the low activity of AP-1 DNA binding in the hippocampus. However, chronic administration of amitriptyline (10 mg/kg, once daily for 3 weeks) significantly increased BDNF protein levels in the hippocampus (by 26.9%) and frontal cortex (by 24.6%). Direct infusion of BDNF (1 microg) into the hippocampal dentate gyrus significantly increased hippocampal AP-1 DNA binding activity. These results suggest that AP-1 transcription factor may be modulated by BDNF and that it may be an important target for the action of antidepressants.