Selective inhibition of amine oxidases differently potentiate the hypophagic effect of benzylamine in mice

In mice deprived of food for 12 h, the i.c.v. or i.p. administration of benzylamine, a substrate common to both monoamine oxidase B and semicarbazide-sensitive benzylamine oxidases, dose-dependently inhibited feeding. This effect was significantly potentiated by selective monoamine oxidase A and B inhibition, suggesting that central monoamines, known to be substrates of these enzymes may be released. The i.p. administration of semicarbazide-sensitive benzylamine oxidase inhibitors, B24 (3,5-ethoxy-4-aminomethylpyridine) and MDL 72374 ((E)-3-phenyl-3-chloroallylamine) strongly potentiated the effect of i.p. but not i.c.v.-administered benzylamine. The hypophagic effect of benzylamine was evaluated following i.c.v. administration, in comparison with the effect of the sympathomimetic compound amphetamine or the Kf channel blocker tetraethylammonium, as reference compounds. Our results make it possible to define benzylamine as a centrally acting hypophagic compound devoid of amphetamine-like motor stimulatory effects and point to a role of B24 and MDL 72274 as specific peripheral enhancers of the pharmacological effects of benzylamine. (C) 2001 Elsevier Science B.V. All rights reserved.