CHANGES IN TRANSPORT OF [C-14] ALPHA-AMINOISOBUTYRIC-ACID ACROSS THE BLOOD-BRAIN-BARRIER DURING PENTYLENETETRAZOL-INDUCED STATUS EPILEPTICUS IN THE IMMATURE RAT

In the present study, we measured the effects of pentylenetetrazol (PT Z)-induced status epilepticus on the blood-brain barrier (BBB) permeab ility in rats at postnatal age 10 (P10) or 21 days (P21). Seizures wer e induced by the repetitive injection of subconvulsive doses of PTZ un til the onset of status epilepticus characterized as the loss of quadr uped posture. The BBB permeability changes to the poorly diffusible am ino acid [C-14]alpha-aminoisobutyric acid (AIB) were measured by autor adiography at 10 min after the onset of status epilepticus. Seizures i nduced a generalized increase in BBS permeability to AIB that was sign ificant in 22 and 26 regions out of the 34 studied at P10 and P21, res pectively. Highest increases over control levels (> 250%) were recorde d at both ages in interpeduncular nucleus, raphe nuclei and trigeminal nerve tractus. Quite high increases (>150%) were recorded in cortical , inferior collicular and thalamic areas at P10 and in inferior collic ulus, cerebellar cortex, hypothalamic and thalamic regions at P21. Cer ebral blood volume measured with [C-14]sucrose over a 2-min period was significantly increased over control levels in hypothalamus and cereb ellum at P10 and in all brain regions, except hippocampus and brainste m, at P21. The widespread increase in BBB permeability is at least par tly related to the blood pressure increase, 55 and 22% over control va lues at P10 and P21, respectively. In the P10 rat, generalized BBB lea kage appears to be correlated to the widespread increase in cerebral m etabolic and blood flow rates that we recorded previously in the same experimental conditions. Conversely, at P21, as previously shown in ad ults, there is a mismatch between the nature of the structures with in creased BBB -permeability and the regional distribution of cerebral bl ood flow and metabolism changes induced by PTZ seizures.