Effects of n-hexanal on dopamine release in the striatum of living rats.
Green odor is present in many green leaves, vegetables, and fruits and is composed of four 6-carbon straight-chain alcohols, n-hexanol, (E)-2-hexenol, (Z)-3-hexenol, and (E)-3-hexenol, and four aldehydes, n-hexanal, (E)-2-hexenal, (Z)-3-hexenal, and (E)-3-hexenal. It has been reported that certain green odor compounds enhance dopamine release from rat brain striatal slices and rat pheochromocytoma cells (PC12 cells). It is well known that intracellular Ca(2+) levels regulate dopamine release. The amount of dopamine released by n-hexanal-treated PC12 cells decreased in cells pretreated with a membrane-permeable Ca(2+) chelator. In this study, the effect of n-hexanal on dopamine release in the brain striatum of living rats was studied using an in vivo brain microdialysis system. Local stimulation with n-hexanal diluted in Ringer's solution to 0.01%, 0.05%, or 0.1% enhanced dopamine release in a concentration-dependent manner. The amount of dopamine released with 0.01% n-hexanal administration significantly declined when either extracellular or intracellular Ca(2+) levels decreased. Furthermore, the extracellular dopamine concentration increased with perfusion of nomifensine, an inhibitor of dopamine uptake into cells. When nomifensine was co-perfused with n-hexanal into the striatum, extracellular dopamine release increased further. Accordingly, the concentration of dopamine metabolite and the ratio of dopamine metabolite to dopamine decreased after treatment with n-hexanal. These responses were similar to those seen with KCl stimulation. These data suggest that n-hexanal stimulates dopamine release but does not inhibit dopamine uptake in the brain striatum of living rats, and that dopamine release associated with n-hexanal is regulated by both extracellular and intracellular Ca(2+) levels.
Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Suruga-ku, Shizuoka 422-8526, Japan.
Hironari
H
Kako
Yoko
Y
Kobayashi
Hidehiko
H
Yokogoshi
D000447:Aldehydes / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D000447:Aldehydes; D018765:Dopamine Uptake Inhibitors; D011189:Potassium Chloride; C010463:n-hexanal; D002118:Calcium; D004298:Dopamine