The administration of
veratramine produced generalized
tremor,
myoclonus, hindlimb abduction, backward gait and Straub tail, similar to the "
5-hydroxytryptamine (5-HT) syndrome", in mice. Pretreatment with
metergoline,
methysergide, mainserin or
cyproheptadine ameliorated
veratramine-induced
myoclonus and
tremor. For suppression of other symptoms,
mianserin and
cyproheptadine were effective.
Metergoline improved hindlimb abduction and Straub tail, but did not inhibit backward gait.
Methysergide was ineffective for the remaining symptoms.
5-Methoxy-N,N-dimethyltryptamine (5-MeODMT) enhanced all these symptoms except for Straub tail. 8-Hydroxy-2-[di-n-propylamino]
tetralin hydrobromide (8-OH-DPAT) augmented
tremor, hindlimb abduction and backward gait, but did not influence
myoclonus and Straub tail. 5-Methoxy-3[1,2,3,6-tetrahydropyridin-4-yl] 1H-indole (
RU 24969) did not modify the symptoms. Destruction of
5-HT neurons using
5,6-dihydroxytryptamine (5,6-DHT) resulted in suppression of the syndrome. The
denervation supersensitivity caused by 5,6-DHT did not increase the response to
veratramine. These findings indicate that part of the site of action of
veratramine may be the presynaptic
5-HT neurons.