Influence of long-term immobilization stress on regional blood-brain barrier permeability, cerebral blood flow and 5-HT level in conscious normotensive young rats.

Eight hours immobilization stress in young rats has increased the blood-brain barrier (BBB) permeability in 12 out of 14 brain regions studied. In the same regions cerebral blood flow (CBF) diminished by 2-37%, but the magnitude of flow reduction was not correlated with the degree of increased BBB permeability. On the other hand, a correlation was observed with increased plasma and brain 5-HT levels. The increased BBB permeability and increased 5-HT levels were prevented by pretreatment with p-CPA, indomethacin and diazepam. Cyproheptadine and vinblastine pretreatment prevented the occurrence of increased BBB permeability alone. The probable mechanism(s) underlying the breakdown of BBB permeability is discussed.