Diferential effect of changes in blood glucose levels on the velocity of propagation of cortical spreading depression in normal and malnourished rats

RESUMO

The effects of intravenous glucose (1ml,40% solution) and insulin (1.5-3U/Kg in 0.2-0.4 ml Ringer solution) on the velocity of propagation (VP) of cortical spreading depression (SD) were studied in 36 well-nourished (W) and 25 malnourished (M) adult (90 days old) Wistar rats of both sexes. Blood levels, measured 40-70 min after glucose, were increased by 330% in the W group (N = 18) and by 202.9% in the M rats (N=12), when compared to the pre-injection levels. Insulin decreased it by 43.5% and 61.2% in W and M rats, respectively (N=13). In the W rats, SD VP decreased after glucose and increased after insulin. The effect of glucose could not be attributed to increases in blood osmolarity, since iv mannitol (1 ml, 20% solution, N = 5) failed to decrease SD VP. The mean ñ SEM VP before and after the treatments were as follows (in mm/min) W rats, glucose 3.31 ñ 0.16 and 3.11 ñ 0.13; insulin 3.50 ñ 0.12 and 3.81 ñ 0.11; mannitol 3.53 ñ 0.46 and 3.92 ñ 0.48. In the M rats, the above effects on SD were not seen (SD VP glucose 3.89 ñ 0.20 and 4.13 ñ 0.24; insulin 3.51 ñ 0.19 and 3.63 ñ 0.17). The results suggest that changes in the production of brain energy influence SD propagation