Demonstration of hereditarily accelerated proliferation in astrocytes derived from spontaneously hypertensive rats

1. We examined the proliferative rates of cultured astrocytes isolated from stroke-prone spontaneously hypertensive rats (SHRSP) and stroke-resistant spontaneously hypertensive rats (SHRSR). Wistar-Kyoto rats (WKY) were used as a control for SHRSP and SHRSR. 2. In the presence of 10% fetal bovine serum (FBS), the doubling time for astrocytes from SHRSP and SHRSR was significantly shorter than WKY. 3. When quiescent astrocytes derived from SHRSP or SHRSR were released from serum-deprivation, the DNA synthesis was stimulated 13.3-fold and 12.5-fold, respectively, whereas only a 7.76-fold increase was observed in WKY astrocytes. 4. Further we studied the effects of two growth factors, epidermal growth factor (EGF) and fibroblast growth factor (FGF) on astrocytes proliferation. EGF induced greater DNA synthesis in SHRSP and SHRSR astrocytes compared with WKY astrocytes, although FGF had little or no effect. 5. Total cholesterol levels in SHRSP astrocytes and SHRSR astrocytes were significantly lower than that of WKY astrocytes, which was consistent with our previous observations in cultured vascular smooth muscle cells. 6. There was no difference in morphology among the cultured astrocytes from the three strains. 7. The abnormality of growth rate and cell membranes composition of astrocytes might be closely related to the genetic phenotypes (acute death of neurons and oedema of astrocytes) of SHRSP or SHRSR.