Abstract
Although Acanthopanax senticosus root extract (ASRE), a functional food used in Japan, improves peripheral blood circulation
and exerts vasorelaxant effects in rats under healthy conditions, the underlying mechanisms
currently remain unclear. Therefore, we investigated the mechanisms responsible for
ASRE-induced relaxation in isolated thoracic aortas using organ bath techniques and
examined whether ASRE affects systemic and peripheral circulation using a photoplethysmographic
tail-cuff system and noncontact laser tissue blood flow meter in Wistar rats. Similar
to acetylcholine (ACh), ASRE induced dose-dependent relaxation in aortas pre-contracted
with phenylephrine; however, in contrast to ACh, ASRE-induced relaxation was partially
inhibited by treatments with antagonists of nitric oxide (NO) synthase and soluble
guanylyl cyclase as well as by endothelium removal. Contractile responses to phenylephrine
or potassium chloride were observed in the presence of ASRE. The oral administration
of ASRE (900 mg/kg/d for 1 wk) decreased systolic blood pressure in rats 3 h after
the treatment and did not affect heart rate, tail blood flow, mass, or velocity; this
decreasing effect was not observed on day 2. A 1-wk treatment with ASRE did not affect
vasorelaxation in response to ASRE. These results demonstrate that ASRE induces vasorelaxation
via endothelial NO production and an NO-independent pathway in rats. Based on these
findings, positive impacts of ASRE on blood pressure and peripheral blood circulation
cannot be expected under healthy conditions as the systemic effects of ASRE are temporary.
Instead, caution is needed to prevent the occurrence of side effects (i.e., orthostatic
dizziness) at the beginning of ASRE dosing.
Key words
Araliaceae -
Acanthopanax senticosus
- blood flow - blood pressure - nitric oxide - Siberian ginseng - vasorelaxation
