ABSTRACT
SL25.1131 [3(S),3a(S)-3-methoxymethyl-7-[4,4,4-trifluorobutoxy]-3,3a,4,5-tetrahydro-1,3-oxazolo[3,4-a]quinolin-1-one] is a new, nonselective, and reversible monoamine oxidase (MAO) inhibitor, belonging to a oxazoloquinolinone series. In vitro studies showed that SL25.1131 inhibits rat brain MAO-A and MAO-B with IC50 values of 6.7 and 16.8 nM and substrate-dependent Ki values of 3.3 and 4.2 nM, respectively. In ex vivo conditions, the oral administration of SL25.1131 induced a dose-dependent inhibition of MAO-A and MAO-B activities in the rat brain with ED50 values of 0.67 and 0.52 mg/kg, respectively. In the rat brain, duodenum, and liver, the inhibition of MAO-A and MAO-B by SL25.1131 (3.5 mg/kg p.o.) was reversible, and the recovery of MAO-A and MAO-B activities was complete 16 h after administration. SL25.1131 (3.5 mg/kg p.o.) increased tissue levels of dopamine (DA), norepinephrine, and 5-hydroxytryptamine and decreased levels of their deaminated metabolites 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindolacetic acid. In mice, SL25.1131 induced a dose-dependent potentiation of 5-hydroxytryptophan-induced tremors and phenylethylamine-induced stereotypies with ED50 values of 0.60 and 2.8 mg/kg p.o., respectively. SL25.1131 was able to reestablish normal striatal dopaminergic tone and locomotor activity in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mice. In addition, when coadministered with L-DOPA, SL25.1131 increased the available DA in the striatum and the duration of L-DOPA-induced hyperactivity. The duration of the effect of L-DOPA on circling behavior in 6-hydroxydopamine-lesioned rats was also increased. The neurochemical profile of SL25.1131 demonstrates that this compound is a mixed, potent, and reversible MAO-A/B inhibitor in vitro, in vivo, and ex vivo. SL25.1131 has therapeutic potential as a symptomatic treatment during the early phase of Parkinson's disease and as an adjunct to L-DOPA therapy during the early and late phases of the disease.
Subject(s)
Maze Learning/drug effects , Monoamine Oxidase Inhibitors/pharmacology , Monoamine Oxidase/metabolism , Nervous System Diseases/metabolism , Oxazoles/pharmacology , Quinolines/pharmacology , 3,4-Dihydroxyphenylacetic Acid/metabolism , Animals , Benzophenones/pharmacology , Brain/drug effects , Brain/enzymology , Corpus Striatum/drug effects , Corpus Striatum/metabolism , Disease Models, Animal , Dopamine/metabolism , Drug Interactions , Levodopa , MPTP Poisoning/metabolism , Mice , Mice, Inbred C57BL , Monoamine Oxidase Inhibitors/therapeutic use , Nervous System Diseases/chemically induced , Nervous System Diseases/drug therapy , Nitrophenols , Oxazoles/therapeutic use , Oxidopamine , Prefrontal Cortex/drug effects , Prefrontal Cortex/metabolism , Quinolines/therapeutic use , Rats , Rats, Sprague-Dawley , Serotonin/metabolism , Stereotyped Behavior/drug effects , Tolcapone , Tremor/chemically induced , Tremor/drug therapy , Tyramine/pharmacologyABSTRACT
We have evaluated the G1H line of transgenic mice overexpressing a familial ALS mutation of SOD1 (Gly-93-->Ala) in tasks assessing different aspects of motor function to determine how early these deficits could be detected and their order of appearance. The earliest deficits were observed in tests of muscle strength and coordination as early as 8 weeks of age and their development appeared to be biphasic, whereas spontaneous activity was not impaired until 15 weeks of age. These studies show that, in addition to the previously demonstrated histological and electromyographic deficits, this transgenic mouse also presents changes in motor function reminiscent of the human disease, reinforcing and extending its validity as an animal model of familial amyotrophic lateral sclerosis (FALS) and allowing the investigation of novel drug treatment for ALS.
