Species differences in subcellular distribution of choline acetylase in the CNS. A study of choline acetylase, acetylcholinestera¬se, 5 hydroxytryptophan decarboxylase and monoamine oxidase in four species

R. E. MCCAMAN; G. RODRÍGUEZ DE LORES ARNAIZ; E. DE ROBERTIS

JOURNAL OF NEUROCHEMISTRY

WILEY-BLACKWELL PUBLISHING, INC

Año: 1965 vol. 12 p. 927 - 935

0022-3042

SPECIES DIFFERENCES IN SUBCELLULAR DISTRIBUTION OF CHOLINE ACETYLASE IN THE CNS A STUDY OF CHOLINE ACETYLASE, ACETYLCHOLINESTERASE, 5-HY DROXYTRYPTOPHAN DECARBOXY LASE, AND MONOAMINE OXIDASE IN FOUR SPECIES* R. E. MCCAMANt, GEORCINA RODR~GUEZ DE LORES ARNAIZ and E. DE ROBERTIS Instituto de Anatomia General y Embriologia, Facultad de Medicina, Universidad de Buenos Aim, Buenos Aires, Argentina (Received 5 April 1965) THE isolation of ACh-rich and ACh-poor nerve endings from the CNS, and the demonstration that ACh is concentrated in a fraction rich in synaptic vesicles, made it of interest to study the subcellular localization of ChAc in those fractions. In rat brain, a direct correlation between ACh content and ChAc activity in the two nerve ending fractions was observed; this result indicates that both the transmitter and the synthesizing enzymes are topographically related within the synaptic complex. A similar close relationship was found in the fraction containing the synaptic vesicles, which were separated from osmotically disrupted nerve endings. In spite of some solubilization, ACh and ChAc were found to have 3.6- and 5.6-fold concentrations, respectively, in synaptic vesicles to the total homogenate (DE ROBERTIS, PELLECRINO DE IRALDI, RODR~GUEZ DE LORES ARNAIZ and SALGANICOFF, 1962; DE ROBERTIS, RODRiCUEZ DE LORES ARNAIZ, SALGANICOFF, PELLECRINO DE IRALDI and ZIEHER, 1963). WHITTAKER, MICHAELSON and KIRKLAND (1964), using osmotic shock and a gradient technique to separate the vesicular fraction from guinea pig brain, confirmed our results for ACh but found that ChAc was not related to the synaptic vesicles. According to them, ChAc is essentially a soluble enzyme which is similar to lactate dehydrogenase and potassium in its subcellular distribution. These authors appeared to question the validity of our results without giving consideration to a possible species difference or taking into account the different technical approaches used. In view of this conflicting report, we have reinvestigated the localization of ChAc in the rat and guinea pig brain and extended this study to the rabbit and pigeon. A new and more precise technique for ChAc was used (MCCAMAN, 1963; MCCAMAN and HUNT, 1965). In this micromethod [14C]acetyl CoA and choline are used as *