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論文
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Masamoto, Kazuto ; Obata, Takayuki ; Kanno, Iwao
概要:
Cerebral blood flow is tightly regulated, and local metabolic demands are met by adjustments to the regional density of
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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 or glial cells in either rapid or slow conduits. In the present study, we report distinct diff erences between the dynamic reactions of cerebral arterial networks in cortical surface and in intracortical tissue regions in response to sensory stimulation. Using confocal and multi-photon excitation laser scanning fluorescence microscopy, we imaged the cortical 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 fi eld of view of 512 by 512 pixels. We consistently observed a stimulus-dependent increase in the lumen diameter of arterial networks in both cortical surface and subsurface regions. The onset time of vasodilation was observed to be ~0.8 sec for the subsurface arterioles（ <40 μm）, which was signifi cantly shorter than the ~1.1 sec vasodilation onset time of the surface arteries （20-120 μm）. The peak dilation accounted for 10% of the pre-stimulus baseline diameter. Further, the propagation of surface arterial vasodilation increased in a stimulus-dependent manner. The results indicate that global vasodilation of upstream parent arteries may be necessary to prevent “blood steal” by inactive regions nearby. Further studies are needed to elucidate the physiological mechanisms underlying the propagation of vasodilation induced by neural stimulation.
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| 2.
論文 |
論文
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Takuwa, Hiroyuki ; Masamoto, Kazuto ; Obata, Takayuki ; Kanno, Iwao
概要:
The mechanism regulating cerebral blood fl ow （CBF） during brain function （neurovascular coupling）has been widely invest
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igated in animals under anesthetized conditions, though anesthesia is known to greatly aff ect neurovascular physiology. The present study aims to develop a novel model for neurovascular coupling studies in awake-behaving mice. Male C57BL/6J mice were initially anesthetized with isofl urane in preparation for attaching the study apparatus to the head. The animal was tethered to the study apparatus but allowed to move spontaneously on a floated ball. The animal behavior and regional CBF in the somatosensory barrel cortex were simultaneously measured with optical motion sensor and laser-Doppler fl owmetry （LDF）, respectively. Anesthesia was discontinued during recovery, while whisker stimulation （frequency 10 Hz and duration 10 or 20 sec） was induced at either the contralateral or ipsilateral side of the LDF recording site. During the experiments, the animals showed no signs of struggling against the head restraint. The intensity of baseline CBF was higher while the animal was under 2% isoflurane aesthesia than it was after anesthesia was stopped. CBF response to stimulation was not observed under anesthesia. After the animal was recovered from anesthesia, an increase in CBF （34 ± 18%） was observed during contralateral stimulation but not during ipsilateral stimulation. The fl uctuation levels of CBF baseline during resting and walking conditions were ±2.7% and ±3.5%, respectively. We observed that these fl uctuations were not due to vibration noises caused by such as air-puff and animal motion in our experimental conditions.
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