Characterization and comparison of lipids in different squid nervous tissues.

We have studied the lipid composition of brain (optic and cerebral lobes), stellate ganglia and fin nerves of the squid. Cholesterol, phosphatidylethanolamine and phosphatidylcholine were the major lipids in these nervous tissues. Phosphatidylethanolamine contained about 3% of its amount in [corrected] plasmalogen form. Phosphatidylserine and -inositol, sphingomyelin and ceramide 2-aminoethylphosphonate were also present in significant amounts. In addition, cardiolipin and free fatty acids were detected in brain (each 2-3% of total lipids) and stellate ganglia (about 1% each), but not in fin nerves. Phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol from brain contained large amounts of polyunsaturated fatty acids, namely 20:4, 20:5 and 22:6 in the n-3 family. On the other hand, phosphatidylcholine, cardiolipin, and sphingomyelin, and ceramide 2-aminoethylphosphonate contained only saturated or monounsaturated C16-C18 fatty acids. The aldehyde moieties of ethanolamine plasmalogen were also C16-C18 saturated or monounsaturated. These lipid compositions are compared with those in other invertebrate nervous systems.

Pharmacological characterization of dopamine receptors in the stellate ganglia with selective DA1 and DA2 receptor agonists and antagonists.

Experiments were performed with fenoldopam (SKF-82526), a selective DA1 receptor agonist, and quinpirole (LY-171555), a selective DA2 receptor agonist, to determine their actions on ganglionic transmission. Fenoldopam caused significant inhibition of the tachycardia elicited during preganglionic stellate stimulation; however, it did not alter the positive chronotropic responses to postganglionic stellate stimulation, suggesting that the compound exerts its inhibitory action at the ganglia. Electrophysiological experiments in the isolated stellate ganglia showed that fenoldopam produced inhibition of ganglionic transmission as indicated by a significant reduction in the magnitude of the compound postganglionic action potential elicited during preganglionic nerve stimulation. The inhibition of ganglionic transmission produced by fenoldopam both under in vivo and in vitro conditions was antagonized by R-sulpiride and metoclopramide, but not by SCH 23390, S-sulpiride or phentolamine. Quinpirole produced significant inhibition of the tachycardia elicited during both preganglionic as well as postganglionic cardiac sympathetic nerve stimulation. This action of quinpirole was antagonized by RS-sulpiride. In electrophysiological experiments it was discovered that quinpirole caused a significant reduction in the magnitude of the compound action potential elicited during stimulation of preganglionic stellate nerve fibers. This inhibition of ganglionic transmission produced by quinpirole was antagonized by S- but not by R-sulpiride. Although phentolamine antagonized the inhibitory action of quinpirole, it was much less effective than S-sulpiride. Norepinephrine also produced inhibition of ganglionic transmission in the isolated stellate ganglia which was antagonized by phentolamine but not by S-sulpiride. These results demonstrate the presence of two subtypes of specific dopamine receptors in the stellate ganglia.(ABSTRACT TRUNCATED AT 250 WORDS)

5-S-Cysteinyldopa in ganglion stellatum.

5-S-Cysteinyldopa, an amino acid formed by nucleophilic addition of cysteine to dopaquinone, has been detected in the ganglion stellatum of the cow in amounts varying between 21 and 35 ng/g ganglionic tissue. Dopa was present in slightly higher quantities. Cysteinyldopa has previously been regarded as a substance unique for the melanocytes, where it forms melanin after oxidation and polymerization. At present only hypothetical explanations of our finding can be offered. The content of 5-S-cysteinyldopa in ganglion stellatum may be the result of dopa oxidation in ganglionic cells. An uptake mechanism for circulating cysteinyldopa may exist. Localization of cysteinyldopa to aberrant melanocytes or to aged SIF-cells in the ganglia should also be borne in mind.

A histochemical investigation on mucopolysaccharides in the dog sympathetic ganglia.

A histochemical study in the dog Superior Cervical ganglion and in the Cervicothoracic or Stellate ganglion is reported. The mucopolysaccharide composition of these ganglia are studied by means of five histochemical techniques. The different histochemical composition between the neurons of these ganglia is investigated. In the sections stained with the PAS technique some neurons appeared more intensely stained than the others. With Thionin or Toluidine blue some neurones appeared more metachromatic than others. A peculiar distribution of the Nissl bodies, related with metachromasia, is reported. In sections stained with the Colloidal Iron method yellow neurons like those presented in the dorsal root ganglia were not found in the sympathetic ganglia. This fact suggests that the yellow neurons might be a different type of neuron. The possibility that the staining variations associated to the distribution of the Nissl bodies perhaps correspond to different functional states of the same type of neurons is also suggested.

Calcium transient in presynaptic terminal of squid giant synapse: detection with aequorin.

Microinjection of aequorin, a bioluminescent protein sensitive tocalcium, into the presynaptic terminal of the squid giant synapse demnonstrated an increase in intracellular calcium ion concentration during repetitive synaptic transmission. Although no light flashes synchronous with individual presynaptic : tion potentials were detected, the results are considered consistent with the hypothesis that entry of calcium into the presynaptic terminal triggers release of e synaptic transmitter substance.