Abstract
ObjectiveTo 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). MethodWistar 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. ResultsAlthough ATD significantly decreased TRP levels in the hippocampus 2h 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. ConclusionChanges 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.
Original language | English |
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Pages (from-to) | 107-113 |
Number of pages | 7 |
Journal | Acta Psychiatrica Scandinavica |
Volume | 128 |
Issue number | 2 |
DOIs | |
Publication status | Published - Aug 2013 |
Keywords
- phosphodiesterase inhibitors
- acute tryptophan depletion
- serotonin
- rat object memory
- CEREBRAL-BLOOD-FLOW
- GELATIN-BASED MIXTURE
- NITRIC-OXIDE SYNTHASE
- AFFECTIVE BEHAVIOR
- SEROTONIN RELEASE
- AMINO-ACIDS
- BRAIN
- DOPAMINE
- CGMP
- NORADRENALINE