Table 1.

Mechanisms of Brain Barriers in Chemical-Induced Neurotoxicity.

Type	Mechanism	Examples	Reference
I	Disrupt barrier structure, followed by increased influx and increased toxicity	Trinitrobenzene	(5)
		Dinitrobenzene	(6)
		NMDA	(7)
		Cyclosporin A	(8)
		Pyridostigmine bromide	(9)
		BCNU	(27)
II	Alter barrier functions, but do not directly damage barrier structure	Aluminum	(10,11)
		Lead	(19,20)
		Manganese	(46)
		Inorganic mercury	(28)
III	Biotransformation of xenobiotics at brain barriers as part of brain defense mechanism	MPTP	(24,25)
		BCB	(26)