Journal of Neurophysiology, Vol 48, Issue 2 451-457, Copyright © 1982 by APS
Dietary choline augments blood choline and cholinergic transmission in terrestrial mollusk Limax maximus
S. R. Barry and A. Gelperin
1. A radioenzymatic assay was used to determine the concentration of
choline in the hemolymph of the terrestrial mollusk Limax maximus
maintained on choline-enriched and choline-deficient diets. The levels of
free choline in the slug's hemolymph varied with the availability of
choline in the diet. The concentration of choline in the plasma of
choline-enriched animals averaged 5.5 microM while the mean circulating
choline level of choline-deprived slugs was 3.3 microM. The difference in
choline levels between the two groups was statistically significant. 2.
Neurophysiological measurements of transmission at the isolated cholinergic
synapses between the salivary burster neuron (SB) and the salivary duct
muscle (SD) showed that this synapse was sensitive to fluctuations in the
external choline concentration within the physiological range. Increases in
exogenous choline from 0.5 to 2.0 microM, from 2.5 to 5.0 microM, and from
5.0 to 15.0 microM were followed by increases in the amplitudes of
SB-elicited junction potentials recorded from the SD by a focal
extracellular electrode. 3. Thus, the SB-SD synapse is sensitive to the
fluctuations in exogenous choline that can occur with a change in diet.
