Effect of Noradrenaline on Phosphatase Activity in Synaptic Membrane of the Rat Brain
Abstract
THE classical experiments of Loewi1 demonstrated the transmitter substance of the sympathetic nervous system to be adrenaline or noradrenaline2,3. Several further investigations have shown a transmitter substance to be present in the central nervous system (CNS), that is, the hypothalamus, the central grey matter of mesencephalon and the area postrema4,7. Differential centrifugation of a CNS homogenate has demonstrated the presence of noradrenaline in the synaptic vesicles of the synaptic junction8-10. Electrophysiological investigation has revealed that electrical stimulation of amygdala or of terminals of bulbo-spinal neurones leads, in both instances, to a reduction of the noradrenaline content of certain areas of the brain11-13. The molecular basis for the action of noradrenaline in the CNS is, however, unknown. Previous investigations of the pharmacological action of noradrenaline, particularly on different enzyme systems14-16, have not provided the experimental evidence basic to a theoretical understanding of physiological events of depolarization and repolarization. The relationship of changes in the ion-flux across the synaptic membrane to the action of a transmitter substance has not been denned. Investigation (our report in preparation) of the distribution of phospholipids and glycolipids free from sialic acid in the sub-cellular fractions of hypothalamus revealed a preponderance of phosphatidyl-serine in the sub-mitochondrial fraction B-C19 using the method of De Robertis et al.8,9. This discovery stimulated us to search for a possible function of phosphatidyl-serine in the synaptic endings. In vitro investigations revealed phosphatidyl-serine to be the only major lipid among phospholipids or glycolipids free from sialic acid of the CNS which binds the noradrenaline17.
- Publication:
-
Nature
- Pub Date:
- January 1967
- DOI:
- 10.1038/213389a0
- Bibcode:
- 1967Natur.213..389C