Correlation of the cerebral microvascular blood flow with brain temperature and electro-acupuncture stimulation

To investigate the relationship between the temperature and the microvascular blood flow of the cerebral cortex, and the influence of electro-acupuncture (EA) on the cortical microcirculation.

High temperature spots on the anterior ectosylvian and low temperature spots on the posterior suprasylvian on the cortical surface of 20 cats were identified using cortical infrared thermography (CIT); the blood flow in the microcirculation on these spots was measured with laser-Doppler flowmetry. EA was given at Zusanli (ST 36) and changes in the blood flow in the cerebral cortex microcirculation were detected.

1) The mean temperatures on the high (34.83 +/- 0.24 degrees C) and low (32.28 +/- 0.27 degrees C) temperature spots were significantly different (P < 0.001); this was indicative of a temperature difference on the cortical surface; 2) The average blood flow in the microcirculation of the high (266.8 +/-19.2 PU) and low (140.8 +/- 9.9 PU) temperature spots was significantly different (P < 0.001). 3) On the cortical high temperature spots, the mean blood flow in the microcirculation significantly increased from 266.8 +/- 86.8 PU before EA, to 422.5 +/- 47.4 PU following 5 minutes of EA (58.35%; P < 0.01), and 431.8 +/- 52.8 PU 5 minutes after ceasing EA (61.84%; P < 0.01). 4) On the low temperature spots, there were no significant differences in blood flow following 5 minutes of EA (146.3 +/- 11.5 PU), and 5 minutes after ceasing EA (140.5 +/- 11.6 PU), when compared with that before acupuncture (140.8 +/- 9.9 PU; P > 0.9).

The high temperature spots of the cortex are active functional regions of neurons with higher blood flow and a stronger response to EA. EA induces a significant increase in blood flow in the high temperature spots of the cortex.