Ryogo Yui

An electron microscopic study on enkephalin-like immunoreactive nerve fibers in the celiac ganglion of guinea pigs.

Enkephalin-like immunoreactive nerve fibers in the celiac ganglion of guinea pigs were characterized by a high population of large granular vesicles mixed with small clear vesicles. The immunoreactive material is confined to the large granular vesicles. The immunoreactive nerve fibers formed many axo-dendritic as well as axo-somatic synapses and also formed a few synapses with presumed preganglionic axons containing numerous vesicles. The immunoreactive fibers were regarded as presynaptic at these synapses. These findings suggest that enkephalin might play a role as a neurotransmitter or neuromodulator in the ganglionic transmission of this prevertebral ganglion.

Evolutionary aspects of “brain-gut peptides”: An immunohistochemical study

Phylogeny of biogenic peptides and their source cells was studied by immunohistochemistry and electron microscopy. The distribution of the peptide containing neurons and paraneurons in the brain and in the gastroenteropancreatic endocrine system was depicted, especially in the bullfrog as the representative of deuterostomia and in the cockroach and some other insects as the representatives of protostomia. Stress was given to: (1) calcitonin-immunoreactive neurons in bullfrog hypothalamus and PP-reactive neurons in the cockroach protocerebrum as instances of transmissional-hormonal partition of a neuropeptide, (2) open-type endocrine cells in the gut structurally and functionally common to the protostomia and deuterostomia, and (3) phylogeny of the prohormones with special reference to big gastrin and proglucagon (glicentin).

Immunohistochemical studies on peptide neurons in the hypothalamus of the bullfrog Rana catesbeiana

The hypothalamus of the bullfrod Rana catesbeiana was examined immunohistochemically by using the indirect immunoperoxidase and the peroxidase-antiperoxidase (PAP) methods. Seven kinds of bioactive peptides were demonstrated in different neuronal somata and fibers located in the preoptic and infundibular areas of the bullfrog. The preoptic nucleus contains β-endorphin-, substance P-, and calcitonin-immunoreactive cells and fibers in its anterior part. Neuronal somata immunoreactive for somatostatin are scattered in the magnocellular preoptic nucleus. Pancreatic polypeptide (PP)-, calcitonin-, somatostatin-, gastrin-, methionine (Met)-enkephalin-, and substance P-immunoreactive neurons and fibers are found in the nucleus infundibularis ventralis. Met-enkephalin-immunoreactive cells occurs also in the ventral part of the nucleus infundibularis dorsalis. Most of the peptide neurons in the bullfrog hypothalamus are multipolar in shape, whereas some are cerebrospinal fluid (CSF)-contacting in type. This type includes substance P- and somatostatin-immunoreactive neurons in the preoptic nucleus and calcitonin-immunoreactive ones in the nucleus infundibularis ventralis. Immunoreactive substances often are gathered to the knobbed end of the CSF-contacting neuronal process and this finding supports the view that neurosecretions may be released into the CSF. Some, if not all, of the above mentioned neurons containing Met-enkephalin-, β-endorphin-, calcitonin-, gastrin-, and somatostatin-like immunoreactivities send their axons to the median eminence, where they are beaded in shape surrounding the blood capillaries, suggesting the release these bioactive substances into the hypothalamo-hypophyseal portal circulation. Possible regulation of the adenohypophyseal secretion by these neuronal peptides are proposed. In the neurohypophysis, somatostatin-, and Met-enkephalin-like immunoreactivities are localized in the nerve terminals abutting on the blood capillaries. Through the general circulation these peptides presumably exert certain unknown actions in remote targets.

Neuropeptide immunocytochemistry in protostomian invertebrates, with special reference to insects and molluscs

In some molluscs (Aplysia and Fusitriton) and insects (silkworm and cricket), occurrence and distribution of neuropeptides in the nervous system and gut were studied with following results: in these invertebrates and also in planaria, PP-like immunoreactivity is extensively distributed in neurons and (in insects) in gut endocrine paraneurons. These cells are negative for NPY, the mammalian neuropeptide related to PP in molecular structure. PHI-like immunoreactivity is widely distributed in the neurons of those invertebrates; it occurs also in gut endocrine paraneurons in insects. The PHI-immunopositive cells are immunonegative for VIP and the coexistence of both peptides due to the common precursor in mammals cannot be recognized in these invertebrates. Immunoreactivity for urotensin I, the neuropeptide derived from teleostean urophysial neurons, is widely distributed in the neurons of the invertebrates. In insects (cricket) it occurs in gut endocrine cells.

Presence of α-neo-endorphin-like immunoreactivity in the posterior lobe of the pituitary gland

Abstract α-neo-endorphin-like immunoreactivity was demonstrated in the nerve fibers and Herrings bodies in the posterior lobe of rat pituitary glands by an indirect immunoperoxidase method using α-neo-endorphin-antiserum. The number of α-neo-endorphin positive fibers and Herrings bodies did not decrease in the sections in which α-neo-endorphin-antisera pretreated with oxytocin, ADH and leu-enkephalin were used as primary antisera. In view of the reports that met-enkephalin, leu-enkephalin and dynorphin were present in the posterior lobe of the pituitary gland, this finding suggested that there were four kinds of opiate-like peptides in the posterior lobes of the pituitary gland. Furthermore, by staining alternately 3he serial sections of the rat pituitary glands with ADH and α-neo-endorphin-antisera, it was revealed that α-neo-endorphin-positive Herrings bodies were identical to a large number of ADH positive Herrings bodies. This finding, together with the observation that morphine injection caused ADH release, suggested that α-neo-endorphin may play an important role in the regulation of ADH release.

Immunohistochemical studies on peptide- and amine-containing endocrine cells and nerves in the gut and the rectal gland of the ratfish Chimaera monstrosa

SummaryThe occurrence and distribution of endocrine cells and nerves were immunohistochemically demonstrated in the gut and rectal gland of the ratfish Chimaera monstrosa (Holocephala). The epithelium of the gut mucosa revealed open-type endocrine cells exhibiting immunoreactivity for serotonin (5HT), gastrin/cholecystokinin (CCK), pancreatic polypeptide (PP)/FMRFamide, somatostatin, glucagon, substance P or gastrin-releasing peptide (GRP). The rectum contained a large number of closed-type endocrine cells in the basal layer of its stratified epithelium; the majority contained 5HT- and GRP-like immunoreactivity in the same cytoplasm, whereas others were immunoreactive for substance P. The rectal gland revealed closed-type endocrine cells located in the collecting duct epithelium. Most of these contained substance P-like immunoreactivity, although some reacted either to antibody against somatostatin or against 5HT. Four types of nerves were identified in the gut and the rectal gland. The nerve cells and fibers that were immunoreactive for vasoactive intestinal peptide (VIP) and GRP formed dense plexuses in the lamina propria, submucosa and muscular layer of the gut and rectal gland. A sparse network of gastrin- and 5HT-immunoreactive nerve fibers was found in the mucosa and the muscular layer of the gut. The present study demonstrated for the first time the occurrence of the closed-type endocrine cells in the mucosa of the rectum and rectal gland of the ratfish. These abundant cells presumably secrete 5HT and/or peptides in response to mechanical stimuli in the gut and the rectal gland. The peptide-containing nerves may be involved in the regulation of secretion by the rectal gland.

Glucagon-related peptides in the rat hypothalamus

SummaryImmunohistochemically, nerve fibers and terminals reacting with anti-N-terminal-specific but not with anti-C-terminal-specific glucagon antiserum were observed in the following rat hypothalamic regions: paraventricular nucleus, supraoptic nucleus, anterior hypothalamus, arcuate nucleus, ventromedial hypothalamic nucleus and median eminence. Few fibers and terminals were demonstrated in the lateral hypothalamic area and dorsomedial hypothalamic nucleus. Radioimmunoassay data indicated that the concentration of gut glucagon-like immunoreactivity was higher in the ventromedial nucleus than in the lateral hypothalamic area. In food-deprived conditions, this concentration increased in both these parts. This was also verified in immunostained preparations in which a marked enhancement of gut glucagon-like immunoreactivity-containing fibers and terminals was observed in many hypothalamic regions. Several immunoreactive cell bodies were found in the ventromedial and arcuate nuclei of starved rats. Both biochemical and morphological data suggest that glucagon-related peptides may act as neurotransmitters or neuromodulators in the hypothalamus and may be involved in the central regulatory mechanism related to feeding behavior and energy metabolism.

The Paraneuron Concept and its Implications in Neurobiology

Paraneurons are receptosecretory cells which produce aminic and/or peptidic messengers, contain them in the form of membrane-bounded granules and release them in response to adequate stimuli. All these features of paraneurons are common to neurons, and there is no distinct boundary between neurons and paraneurons (Fujita 1976; Fujita and Kobayashi 1979a).