Effect of sympathetic stimulation on the blood brain barrier dysfunction induced by amphetamine and by epileptic seizures.

Stimulation of the sympathetic nerves to the brain is known to make the resistance vessels able to withstand a higher blood pressure, i.e. to prevent blood-brain barrier (BBB) dysfunction and overperfusion in acute hypertension. When hypertension occurs concomitantly with a metabolic vasodilatation e.g. during epileptic seizures and after amphetamine-administration, protein leakage in the brain is more pronounced than in hypertension per se. Unilateral stimulation of the cervical sympathetic chain during the administration of amphetamine or bicuculline--the latter a GABA-receptor blocking substance that induces epileptic activity--attenuated the leakage of Evans blue-albumin and 125IHSA into the brain. Our results thus indicate a prophylactic effect of sympathetic stimulation also when hypertension is combined with a metabolically induced vasodilatation. The sympathetic nerves may constrict both extracerebral arteries and intracerebral resistance vessels. Unexpectedly the effect on the BBB of unilateral stimulation was to a great extent bilateral under the present experimental conditions.