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Addition of gabaculine to brain and liver extracts caused great inhibition of GABA-T activity, a much lesser but still significant inhibition of ALA-T activity, and very little inhibition of ASP-T activity. In contrast, intramuscular administration of gabaculine to mice resulted in considerable inhibition of all three enzyme activities in liver, the order of sensitivity being ALA-T greater than GABA-T greater than ASP-T. The effect of the administered gabaculine on the brain enzyme activities was more along the lines seen in the in vitro experiments but, even here, the relative sensitivities of GABA-T and ALA-T to the inhibition were much more similar than might have been predicted from the in vitro experiments.

2-Pyrrolidylacetic acid and β-(2-pyrrolidyl)propionic acid hydrochloride have been prepared by hydrogenation of ethyl 2-pyrrolylacetate and diethyl 2-pyrrolylmethylenemalonate respectively, over rhodium on alumina in HCl solution, followed by acidic hydrolysis. Similarly, 1-methylnipecotic acid, 1-methylisonipecotic acid, 2- and 3-piperidine-acetic acid, and 3-piperidine-propionic acid hydrochlorides have been prepared by hydrogenation of the corresponding pyridine-alkanoic acid hydrochlorides over platinum oxide, rhodium on alumina, or palladium on carbon in water.

2-Pyrrolidylacetic acid and β-(2-pyrrolidyl)propionic acid hydrochloride have been prepared by hydrogenation of ethyl 2-pyrrolylacetate and diethyl 2-pyrrolylmethylenemalonate respectively, over rhodium on alumina in HCl solution, followed by acidic hydrolysis. Similarly, 1-methylnipecotic acid, 1-methylisonipecotic acid, 2- and 3-piperidine-acetic acid, and 3-piperidine-propionic acid hydrochlorides have been prepared by hydrogenation of the corresponding pyridine-alkanoic acid hydrochlorides over platinum oxide, rhodium on alumina, or palladium on carbon in water.