Ninjin'yoeito Modulates Baseline and Reperfusion-Induced Changes in the Arteriole Diameter and Blood Flow in the Cerebral Cortex of Anesthetized Mice.

Objective: Intragastric administration of ninjin'yoeito (NYT), a traditional Japanese herbal medicine, reportedly prevents the decrease in baseline cerebral blood flow (CBF) in the cortex following gastric administration of water. We investigated the effect of NYT on baseline and dynamic changes in cerebral cortical arteriole diameter.

Methods: Urethane-anesthetized mice were intragastrically administered 1 g/kg NYT or distilled water (DW). The artery in the left parietal cortex was imaged using two-photon microscopy. The baseline diameter of penetrating arterioles was measured before and 50-60 min after administration. Dynamic CBF and arteriole diameter changes before, during, and after transient occlusion of the left common carotid artery were measured approximately 10 min after administration.

Results: DW decreased the baseline diameter of the penetrating arterioles, whereas NYT did not. During occlusion, the increase in penetrating arteriole diameter was comparable for DW and NYT; however, during reperfusion, the return to preocclusion diameter was slower for NYT than DW. Laser-speckle contrast imaging confirmed that CBF, although comparable during occlusion, was higher during reperfusion for NYT than DW.

Conclusions: These results suggest that NYT attenuates vasoconstriction in penetrating arterioles after intragastric administration and during cerebral reperfusion, contributing to CBF regulation.