Keratinocyte Proliferation in Aged Rat Skin by High Voltage Pulsed Current Stimulation

The purpose of this study was to determine the effect of high voltage pulsed current (HVPC) stimulation on proliferative activities of basal keratinocytes by measured nucleolar organizer region (NOR) expression and thickness of spinous layer in aged rat skin. Fifty-one weeks old twelve male Sprague-Dawley rats (300∼350g) were divided into control and HVPC stimulation groups. Each animal's hair on the back were removed. The HVPC stimulation group received an negative monophasic twin peak pulsed current stimulation with 50 V, while the control group was given the same treatment without electricity. The rats were sacrificed after 3 weeks. The biopsy specimens were fixed in formalin, embedded in paraffin and stained with hematoxyline-eosin and silver nitrate. The thickness of basal to granular layer of the epidennis were measured using a light microscope and computerized image analysis system. The number of argyrophilic nucleolar organizer region (AgNOR) were counted using a light microscope and computerized image analysis system and calculated as the mean number of AgNOR per nucleus in the basal keratinocyte. By using a Student's t-test, an increase in the thickness of basal-spinous layer (P<0.001) of epidermis can be observed in HVPC stimulation rats as compared with the control rats, whereas the thickness of the granular layer is not affected. A Student's t-test showed a significantly higher mean NOR number per nucleus of the basal keratinocyte in the HVPC stimulation rats than control rats (P<0.001). There was significantly positive correlation between the NOR number and the thickness of basal-spinous layer (r=0.80, P<0.05). These results suggest that the HVPC stimulation may increase the thickness of spinous layer in the epidennis due to increased proliferative activities of basal keratinocytes in epidennis in aged rat skin.