Effect of carbon tetrachloride administration on the synthesis of triglycerides and phospholipids in rat liver

In vivo incorporation of choline-methyl-(14)C into liver lecithin and its biosynthetic precursors was studied in CCl(4)-treated rats. Radioactivity in cytidine diphosphoryl (CDP-)choline and lecithin was reduced to one-third of control levels, whereas that of phosphorylcholine was increased to 4.7 times control levels. Incorporation of phosphorylcholine-(32)P into lecithin by homogenates prepared from livers of CCl(4)-treated animals was reduced, but conversion of CDP-choline-(32)P to lecithin by the isolated microsomal fraction did not show any significant depression. A block in the synthesis of CDP-choline is indicated. The in vivo utilization of methionine for lecithin synthesis was not affected. After intravenous injection of palmitic acid-1-(14)C, radioactivity of triglycerides from microsomal and mitochondrial fractions was markedly lower than the controls, whereas radioactivity of triglycerides in the soluble fraction was greatly increased. Radioactivity of diglycerides changed from 0.5% of total lipids in the control to 10% of total lipids in CCl(4)-treated animals. Incorporation of palmitic acid into phospholipids was also suppressed. The results demonstrate that synthesis of both phospholipids and triglycerides is inhibited in rats 4-5 hr after CCl(4) administration.     

Electron microscopic histochemistry of acetylcholinesterase of rat brain by Karnovsky's method

Summary Karnovsky's electron microscopic acetylcholinesterase method was successfully applied to rat brain fixed by vascular perfusion with either 2% glutataldehyde or 4% formaldehyde. 2% glutaraldehyde showed better fine structure but worse preservation of the enzyme than 4% formaldehyde.In the neuropil of the caudate nucleus, locus coeruleus and dorsal nucleus of the vagus, AChE activity was most intensely demonstrated on the plasma membranes of preterminal axons and somewhat less strongly on those of axon terminals and contacting dendritic branches. The axoplasm and synaptic vesicles were usually negative, while the cytoplasm and neurotubules of the dendritic branches showed some activity. In the nodule and uvula of the cerebellum moderate activity was exhibited on the synaptic contacts between the mossy fiber endings and granule cell dendrites. In the hypothalamus and other autonomic regions the characteristic coexistence of AChE and granulated vesicles of axon terminals could be demonstrated.In the perikaryon of positive nerve cells, AChE was observed strongly in the cytoplasm, disseminated irregularly or attached to the endoplasmic reticulum, while it was absent in the mitochondria and lysosomal dense bodies.