Experimental allergic encephalitis; treatment with drugs which alter CNS serotonin levels

Lennon and Carnegie have proposed that the clinical symptomatology of experimental allergic encephalitis (EAE), an acute autoimmune demyelinating disease, may be due, at least in part, to an immune response directed against CNS serotonin receptors. To test this hypothesis we treated strain 13 guinea pigs, which had been immunized with guinea pig basic protein (GPBP) in complete Freund's adjuvant (CFA), with drugs known to affect central nervous system (CNS) serotonin levels. These drugs included imipramine hydrochloride, tryptophan and carbidopa which increase CNS serotonin and reserpine which decreases it. Five experiments were conducted in which all immunized animals treated with saline only died, as expected, as did all animals treated with reserpine which died even more quickly. A significant proportion of animals treated with the other three drugs, alone or in combination, survived or lived longer than controls. We conclude that survival of animals with EAE is enhanced by treatment with these drugs. We suggest that further evaluation of a possible blockade in serotonin transmission in EAE and multiple sclerosis (MS) is warrented, since, if such a blockade were demonstrated, it is possible that these drugs may have potential for therapeutic efficacy in patients with MS.