No effect of acute tryptophan depletion on phosphodiesterase inhibition–related improvements of short-term object memory in male Wistar rats
Article first published online: 17 JUN 2013
© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Acta Psychiatrica Scandinavica
Special Issue: “Acute Tryptophan Depletion in Translational Psychiatric Research”, GUEST EDITOR Florian Daniel Zepf
Volume 128, Issue 2, pages 107–113, August 2013
How to Cite
No effect of acute tryptophan depletion on phosphodiesterase inhibition–related improvements of short-term object memory in male Wistar rats, , , , , .
- Issue published online: 7 JUL 2013
- Article first published online: 17 JUN 2013
- Manuscript Accepted: 16 MAY 2013
- EU framework 6 Integrated Project NEWMOOD. Grant Number: CT2004-503474
- phosphodiesterase inhibitors;
- acute tryptophan depletion;
- rat object memory
To further explore the implication of the serotonin (5-HT) system in the improvement of rat short-term object recognition after administration of the type 2 phosphodiesterase inhibitor (PDE-I) BAY 60-7550 and the type 5 PDE-I vardenafil, the effect of PDE2 and PDE5 inhibition upon central amino acid levels, 5-HT, and related parameters were measured after applying acute tryptophan depletion (ATD).
Wistar rats were orally administered saline or a protein–carbohydrate mixture with or without tryptophan (TRP). TRP-depleted animals additionally received an oral vehicle injection or the PDE inhibitors BAY 60–7550 or vardenafil at a dose known to improve object memory performance.
Although ATD significantly decreased TRP levels in the hippocampus 2 h after administration, 5-HT levels appeared only moderately affected, without any changes observed in the amount of 5-HIAA or 5-HT turnover rate. Moreover, no effects of PDE inhibition upon 5-HT or related parameters were observed.
Changes in 5-HT neurotransmitter activity might be excluded as a potential underlying mechanism of the previously reported ability of PDE inhibitors to improve short-term object memory in rats. It is suggested that a decrease in cerebral blood flow potentially underlies ATD-induced object memory deficits, most likely due to decrease in NO synthesis.