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Cerebral blood flow is tightly regulated, and local metabolic demands are met by adjustments to theregional density of microvascular networks and by temporal and spatial changes in microvascular blood flow.Cerebral blood flow regulation may involve communication between and across the vascular cells and neural orglial cells in either rapid or slow conduits. In the present study, we report distinct diff erences between the dynamicreactions of cerebral arterial networks in cortical surface and in intracortical tissue regions in response to sensorystimulation. Using confocal and multi-photon excitation laser scanning fluorescence microscopy, we imaged thecortical surface and subsurface vascular networks in the somatosensory cortex of isoflurane-anesthetized rats.Changes in lumen diameter were imaged at a rate of 13 frames per second with a field of view of 512 by 512 pixels.We consistently observed a stimulus-dependent increase in the lumen diameter of arterial networks in both corticalsurface and subsurface regions. The onset time of vasodilation was observed to be ~0.8 sec for the subsurfacearterioles(

The mechanism regulating cerebral blood flow (CBF) during brain functions (neurovascular coupling) was widely investigated with animals under the anesthetized condition. However, anesthesia is known to greatly affect neurovascular coupling and systemic physiology. Therefore, the present study aimed to develop a novel model for neurovascular coupling studies in awake-behaving mice. The male C57BL/6J mice (5-7 weeks) were initially anesthetized with isoflurane (2.5%) for the preparation of head attachment to apparatus. The skin of the head was cut and a metal head plate was attached to the skull. The animal was tethered by screwing the head plate onto apparatus, and then the anesthesia was discontinued for recovery of the animal. The regional CBF in the somatosensory barrel cortex was continuously measured with laser-Doppler flowmetry (LDF). Behavior of animal was also recorded using a digital camera. Whisker stimulation (frequency 10 Hz and duration 10 sec) was induced to the contralateral side of LDF recording site. During experiments, the animals showed no signs of struggling against the head restraint. Based on the type of the animal behavior, the experiment period was separated into three phases (grooming, running and resting). The CBF was observed to be stable during both resting and running phases, showing negligible motion artifacts. The increase in CBF was observed during grooming and whisker stimulation, which was higher than that in the anesthetized condition. In conclusion, the present model allows for the dynamic study of neurovascular coupling in awake-behaving mice., The 11th Meeting of Hirosaki International Forum of Medical Science