抄録
The purpose of this study is to evaluate whether the level of serotonergic activity in brain can be estimated by measurement of serotonin (5-HT) concentration in blood. Although it has been long suggested that the monoamines including 5-HT does not transport across the blood-brain barrier (BBB), a recent study demonstrated an existence of 5-HT transport system at BBB by in vitro study. The present study was conducted to evaluate this notion by in vivo study. We examined a change in 5-HT level in whole blood, when brain 5-HT level was elevated by intravenous administration of 5-HTP in an anesthetized, spontaneously breathing rat with and without gastrointestinal resection, namely non-GI rat and control rat. Brain 5-HT level was measured by microdialysis method and HPLC system: samples were corrected every 10 minutes in medial prefrontal cortex in non-GI rat and control rat. We also measured 5-HT concentration in whole blood before and after 5-HTP loads. We found that blood 5-HT level showed a clear augmentation whenever brain 5-HT level was elevated by 5-HTP either non-GI rat or control rat. These results indicated that an increase in blood 5-HT level was induced an increase in brain 5-HT level. [Jpn J Physiol 54 Suppl:S216 (2004)]
