Junzo Ochi

Occurrence of dopamine-containing neurons in the midbrain raphe nuclei of the rat

Abstract Formaldehyde-induced fluorescence histochemistry, by the use of the improved filter system, revealed that dorsal and median raphe nuclei contain in varying numbers blue-green fluorescent neurons among a large number of yellow fluorescent serotonin-containing neurons. Pharmacological treatments indicated the presence of catecholamine in the blue-green fluorescent neurons. Moreover, microspectrofluorometry identified the catecholamine therein as dopamine, based on an excitation maximum shift characteristic of dopamine fluorescence caused by HCl vapor. Significance of these dopaminergic neurons in the raphe nuclei is suggested.

Topographical Distribution of Neurons Containing Endothelin Type A Receptor in the Rat Brain

Endothelin (ET) was originally identified as a vasoactive peptide biosynthesized in vascular endothelial cells. Because ET has also been found in the brain as a neuropeptide, it has been thought to belong to the group of brain‐vascular peptide hormones. To date, type A and type B receptors for ET have been found. To elucidate the topographic distribution of type A receptor (ET‐AR) in the brain, we raised a specific antibody to the C‐terminal (64 amino acids) peptide of rat ET‐AR and immunostained rat brain sections with this antibody. Immunoreactivity for ET‐AR was detected in neuronal cell bodies and also in the many proximal and some distal parts of their fibers. Nerve cell bodies containing strong ET‐AR‐ immunoreactivity were distributed in the lateral part of the reticular formation, the nucleus of the solitary tract and its surrounding area, the dorsal midline area and medial longitudinal fasciculus, the subependymal layer of the fourth ventricular roof, the caudolateral area of the pontine tegmentum, the locus coeruleus, the rostral pontine area of the lateral reticular formation, the retrorubral area, the substantia nigra, the ventral tegmental area, the periventricular region lateral to the rostral mesencephalic aqueduct and caudal third ventricle, the arcuate hypothalamic nucleus, the caudomedial area of the zona incerta, the periventricular hypothalamic nucleus, the parvocellular portion of the paraventricular hypothalamic nucleus, and the periglomerular region of the olfactory bulb. In addition, the Purkinje cells of the cerebellar cortex, the nerve cells in the mesencephalic trigeminal nucleus, and the magnocellular neurons of the supraoptic and paraventricular hypothalamic nuclei showed weak immunoreactivity. The distribution of highly ET‐AR‐immunoreactive neurons is quite similar to that of catecholamine neurons. J. Comp. Neurol. 389:348–360, 1997.

Cytological evidence for different types of cerebrospinal fluid-contacting subependymal cells in the preoptic and infundibular recesses of the frog

SummaryBlue-green fluorescent subependymal cells with intraventricular processes were shown by the fluorescent histochemical method to be distributed from the preoptic recess to the infundibular recess of the frog hypothalamus. Electron microscopy revealed at least two types of CSF-contacting subependymal cells, type 1 containing large dense granules (about 100–200 nm in diameter) and type 2 containing small dense core vesicles (about 60–100 nm in diameter). Subsequent to fixation in permanganate solution, the small dense core vesicles in type 2 cells reacted with the fixative and consistently showed a dense content. However, the large granules in type 1 cells were mostly pale or less dense after this fixation.Two hours after intraventricular injection of 3H-dopamine, a large number of silver grains appeared only in the cytoplasm of intraventricular processes possessing dense core vesicles (type 2 cells). A few grains were also found in the perikarya. It is concluded that type 2 cells are catecholamine-storing cells. It is suggested that type 1 cells in the infundibular recess are peptidergic neurons which may secrete some hypothalamic regulating hormones of the anterior pituitary. Most of these cells in the preoptic recess belong to the neurosecretory cells of the preoptic nucleus, while some cells probably function similarly to those in the infundibular recess.

Immunohistochemical demonstration of the serotonin-containing subependymal cells in the frog hypothalamus

SummaryThe localization of serotonin(5HT)-containing subependymal cells was demonstrated by immunohistochemistry. The 5HT-containing subependymal cells were predominantly located in the paraventricular organ, while a small number of them were situated in the nucleus infundibularis dorsalis. The basal processes of these 5HT cells of the paraventricular organ appeared to have contact with the wall of blood vessels. The result was discussed in comparison with that obtained by the formaldehyde induced fluorescence (FIF) method.

Distribution of taurine-like immunoreactivity in the mouse liver during ontogeny and after carbon tetrachloride or phenobarbital intoxication

SummaryThe ontogenic pattern of development of taurine-like immunoreactivity (TLI) was studied in the mouse liver. The effect on adult mice of carbon tetrachloride or phenobarbital treatment was also examined. Light-microscopically, granules of TLI were first found in the liver from 17-day-old embryos, diffusely distributed throughout the lobules. These positive granules increased with age, were most numerous in the two-week-old mouse, and were notably decreased in the central region of some lobules in the three-week-old mouse. In mature mice, hepatocytes containing TLI-positive granules were distributed unevenly in each liver lobule, and were located predominantly in the peripheral region. Electron-microscopically, TLI was observed in small vesicles in the cytoplasm of hepatocytes and was found mainly in the cisternal lumen of smooth-surfaced endoplasmic reticulum. Some taurine-positive vesicles surrounding the reticulum seemed to associate with the protoplasm. Similar positive vesicles were often located near the bile canaliculi. In carbon tetrachloride-intoxicated mature mice, TLI was no longer limited to the peripheral region of lobules; hepatocytes situated in the central region of lobules also contained intense TLI. In mice injected with a small and repeated dose of phenobarbital, the distribution pattern of TLI was similar to that in the untreated group. However, in mice injected with a large dose of phenobarbital, TLI was markedly increased, especially in the central region of lobules. The results demonstrate that the distribution pattern of TLI in mouse liver changes during development, and that the pattern in mature mice is affected by intoxication with carbon tetrachloride or a toxic dose of phenobarbital.

Dopaminergic innervation and inhibition of ciliary movement in the ciliated epithelium of frog palatine mucosa

The effect of dopamine on ciliary movement and the existence of dopamine-containing cells in the ciliated epithelium of frog palatine mucosa were investigated pharmacologically and by means of electron and fluorescence microscopy, respectively. Ciliary movement was suppressed markedly when the perfusion medium contained 10(-6) M dopamine, thereby indicating that dopamine has a suppressive effect on ciliary movement. Electron microscopy revealed at least two types of granule-containing (GC) cells, type 1 cells containing small spherical granular vesicles (about 100-150 nm in diameter) and type 2 cells containing elongated dense granules (about 150 X 250 nm in diameter). One hour after systemic administration of dihydroxyphenylalanine-[3H(G)] [( 3H]DOPA), a large number of silver grains appeared only in type 2 GC cells, thus indicating that type 2 cells are catecholamine-storing. Blue-green fluorescent cells were detected in the ciliated epithelium. On microspectrofluorometry, catecholamine fluorescence in the cells showed a main excitation and emission maxima at 415 and 480 nm, respectively. When the fluorescent cells were exposed to HCl vapor for several s, the excitation peak shifted to 380 nm and this peak was unchanged after treatment for an additional 5 min. It may be considered that these fluorescent cells contain dopamine and correspond to type 2 GC cells. A possible functional relationship between regulation of ciliary movement and dopamine-containing cells was also discussed.

Monoamine-containing subependymal cells of the lamprey: Evidence from combined fluorescence histochemistry and electron microscopy

SummaryTwo types of monoamine-containing subependymal cells were studied microspectrofluorometrically and electron microscopically. Microspectrofluorometric analyzes showed that yellow fluorescent cells contained 5HT and blue-green fluorescent cells dopamine (DA). These two types of fluorescent cells could be recognized also in a thin section (about 250 nm thick) mounted on a reference grid. Electron microscopy of the same section revealed that electron dense granules in the 5HT-containing cells are larger (80–140 nm) in size than those in the DA-containing cells (60–100 nm).

2421 Intimate relationship between endothelins and catecholamines through ET-A receptor

Endothelin, a brain-vascular peptide, consists of three isopeptides (ET-l, ET-2 and ET-3) and has two types of receptors (ET-AR and ET-BR), Our previous immunohistochemical study showed that ET-AR exists in the catecholaminergic (CA) neurons in CNS, dopaminergic amacrine cells in retina, and postganglionic sympathetic nerve cells. To elucidate the relationship between ETs and CAs, we immunohistochemically analyzed rat adrenal medulla using antibodies to mature ETs, Big ET-I, Big ET-3 and ET-AR. The animals (Wistar rats weighing 180-250 grams) were sacrificed under anesthesia with sodium pentobarbital (50mgjkg b.wt., i.p.). Many nerve fibers containing Big ET-l were found in adrenal medulla, while no immunoreactivity for mature ETs and Big ET-3 is observed. Noradrenalin cells, which do not contain PNMT enzyme, were immunostained with ET-AR antibody. In these cells, Cat+ release from endogenous stores occurred by ET1 administration to primary culture of adrenal medulla in vitro . Because Big ET1 can be converted