Chikako Tanaka

Histochemical mapping of catecholamine neurons and fiber pathways in the pontine tegmentum of the dog

The distribution of catecholamine-containing neurons and fiber pathways were studied in the dogs pontine tegmentum by the Falck-Hillarp method. There are fundamental similarities between the dog and other mammals. Most catecholamine fluorescent cell bodies in the dog are located within the nucleus locus coeruleus and subcoeruleus in the pontine tegmentum. They are more diffuse and extensive than in the rat, monkey and human, and rather similar to those of the cat. In this study, catecholamine fiber pathways were clearly traced without using the lesion-degeneration technique. The dorsal pathway from the locus coeruleus consists of more compact bundles of non-varicose fibers than the rat, cat and monkey. It runs parallel to the mesencephalic tract of the trigeminal nerve in pons and midbrain. The ventral pathway courses as loosely arranged varicose fibers in the midreticular formation of the pons and sends axon collaterals to the caudal midbrain to form a dense network of varicose fibers. There are fluorescent plexi of fine varicose fibers at the ventromedial and dorsolateral aspect of the superior cerebellar peduncle. Cells of the medial and lateral parabrachial nucleus, in addition to those of locus coeruleus, send fluorescent fibers to this peduncle. No fluorescent fibers are found in other peduncles.

Morphological organization of catecholamine terminals in the diencephalon of the rhesus monkey

The hypothalamus and thalamus of the rhesus monkey were investigated using the fluorescence histochemical method of Falck and Hillarp. The hypothalamus was found to be richly supplied with catecholamine fluorescent nerve terminals with many thick and a few varicosities, whereas nerve terminals with fine varicosities were found to be distributed over the thalamus except for the midline and medial nuclei which were innervated by nerve terminals with thicker and more intense fluorescent varicosities. The morphological characteristics and distribution pattern of catecholamine terminals were similar between the rhesus monkey and the rat. However, some species differences were noted in the suprachiasmatic nucleus, arcuate nucleus and internal layer of infundibulum in the hypothalamus. The pulvinar, which was nonexistent in the rat, had fine terminals.

CYTOLOGICAL LOCALIZATION OF NORADRENALINE, MONOAMINE OXIDASE AND ACETYLCHOLINESTERASE IN SALIVARY GLANDS OF DOG

The cytological localization of noradrenaline, monoamine oxidase and acetylcholinesterase was examined in the salivary glands of the dog. The noradrenaline-fluorescent nerve fibers surrounded the secretory acini of the submaxillary, sublingual and parotid glands, but the density in the sublingual gland was much less than in the other two glands. Noradrenaline fluorescence was not seen in the cytoplasms of the acinar cells nor in the vicinity of the excretory ducts. Intense fluorescence was present outside the smooth muscle layer in various sized arteries. The distribution of monoamine oxidase activity was different from that of noradrenaline fluoresence. All the cells of the secretory acini and the excretory ducts were evenly stained. The distribution of fibers showing acetylcholinesterase activity was different from that of noradrenaline-fluorescent fibers only in that the former fibers were present around the excretory ducts as well. The composition of secretory cells in the submaxillary and sublingual glands is different in dogs and rats. However, the cytological localization of noradrenaline, monoamine oxidase and acetylcholinesterase activities in the salivary glands of the dog was essentially similar to those of the rat. It was concluded, therefore, that the autonomic nerve supply to the salivary glands does not correlate with the type of secretory cells.

Significance of central noradrenergic system on harmaline induced tremor

Since there is degeneration of substantia nigra concomitant with that of locus coeruleus (LC) in patients with Parkinsons disease, the study was performed to determine the role of central norepinephrine (NE) on harmaline induced tremor. The duration of harmaline (10 mg/kg IP) induced tremor was significantly reduced by intraventricular administration of L-thero-3,4-dihydroxyphenylserine (200 micrograms/rat) and 1-NE (50 micrograms/rat) was increased NE levels in the cerebral cortex, striatum, diencephalon, cerebellum and brain stem. Electrical stimulation of bilateral LC suppressed harmaline-induced 10-12/sec EMG activities in the neck muscle. Bilateral LC lesion upon electrocoagulation and 6-hydroxydopamine treatment resulted in a significant prolongation of the duration of harmaline induced tremor, reducing NE levels in the brain. These data suggest that central NE originating in the LC neurons has an inhibitory effect on the development of the tremor induced by harmaline.

Relationship between brain monoamine levels and sidman avoidance behavior in rats treated with tyrosine and tryptophan hydroxylase inhibitors

Summary Correlation between brain monoamine levels and Sidman avoidance response was studied in male Wistar rats whose brain serotonin and/or catecholamines were lowered by treatment with α-methyl-p-tyrosine (α-MT), p -chlorophenylalanine ( p -CPA) and α-propyldopacetamide (H 22/54). A marked decrease in the avoidance response rate was observed after administration of α-MT (2 × 100mg/kg, i.p.). α-MT considerably lowered the brain norepinephrine content but had little effect on brain serotonin. These changes induced by α-MT were reversed by administration of l -DOPA (100 mg/kg, i.p.). On the other hand, p -CPA (300 mg/kg, p.o.) produced a significant increase in the avoidance response rate with a decrease in the number of shocks for several days. p -CPA markedly lowered the brain serotonin level, while leaving the norepinephrine level almost unaffected. The changes caused by p -CPA were completely antagonized by administration of 5-hydroxytryptophan (50 mg/kg, i.p.). H 22/54 did not alter the avoidance response rate although the drug produced a marked reduction of brain norepinephrine and serotonin contents. These results suggest the existence of a catecholaminergic excitatory system and a serotoninergic inhibitory system on the avoidance behavior.

Uptake of noradrenaline by the adrenergic fibers of the submaxillary and sublingual glands of the rat

Abstract The uptake of noradrenaline by the submaxillary and sublingual glands of the rat was investigated histochemically and quantitatively. The administration of noradrenaline increased the noradrenaline fluorescence surrounding the serous acini of the submaxillary gland. The fluorescence in the walls of arterioles of both the submaxillary and sublingual glands was also intensified. On the denervated side, practically no fluorescence was seen after the injection of noradrenaline, although the quantitative determinations revealed a slight increase in noradrenaline levels. After the administration of noradrenaline to the animals treated with monoamine oxidase inhibitor, definite fluorescent fibers appeared among the mucous cells of the sublingual gland, where otherwise little fluorescence was seen. Such fluorescent fibers were never obtained on the denervated side. It was concluded lhat the mucous acini of the sublingual gland are innervated by adrenergic fibers, but normally the amount of noradrenaline in the fibers is too small or its distribution is too diffuse for it to be detected histochemically. A distinction between histochemical and biochemical findings is discussed.

THE AXOPLASMIC TRANSPORT OF THIAMINE IN RAT SCIATIC NERVE

Localization of thiamine in the ligated and unligated sciatic nerve of rats was studied histochemically and biochemically. Thiamine content increased, up to 200% of the unligated nerve, in the nerve just above the ligation 48 hr after surgery. This accumulation of thiamine was observed in the axoplasm just above the ligation. Thiamine in the unligated sciatic nerve exhibited a proximodistal gradient of concentration. The data suggest that accumulation of thiamine is due to the proximodistal streaming of axoplasm.

Developmental and periovulatory changes of ovarian norepinephrine in the rat

Norepinephrine (NE) and dopamine (DA) contained in the rat ovary were determined by high-performance liquid chromatography with electrochemical detection. Concentration of ovarian NE reached adult levels around 5 weeks of age, when the first ovulation occurs. During induction of ovulation, the ovarian NE contents increased slightly during the preovulatory phase, followed by a significant decrease in the postovulatory phase, whereas the turnover of ovarian NE decreased during the preovulatory phase. These results suggest that ovarian noradrenergic nerves were in a somewhat inactivated state during the preovulatory phase. Therefore, ovarian sympathetic nerves are considered to participate in mechanisms of the onset of puberty and ovulation.

Effect of Thiamine on Serotonin Levels in Magnesium-deficient Animals

Abstract To clarify the relationship between thiamine metabolism and peripheral vasodilation symptoms seen in the early stages of dietary magnesium deficiency, various synthetic diets were administered to rats. After a 4-wk period of thiamine excess and magnesium-deficient diet, blood serotonin levels increased significantly. A thiamine-deficient and magnesium-deficient diet revealed no elevation of blood serotonin. Serotonin in stomach and intestine increased in the excess-thiamine, magnesium-deficient group. Blood magnesium concentration decreased markedly in thiamine-supplemented, magnesium-deficient groups but not in the thiamine-deficient magnesium-deficient group. A possible explanation of the mechanism is presented.