Hirofumi Kuramoto

Substance P-like immunoreactivity in adrenal chromaffin cells and intra-adrenal nerve fibers of rats

SummaryThe present peroxidase-antiperoxidase immunohistochemical study demonstrated a relatively small number of cells with substance P(SP)-like immunoreactivity in the adrenal medulla of rats. These cells were found alone or in small groups, were polygonal in shape and lacked long cytoplasmic processes. At immunoelectron microscopy, the immunoreactive cells were characterized by abundant granular vesicles, and the immunoreactive material was confined to the round core of the vesicles. Thus, it is suggested that SP co-exists with catecholamines in a population of chromaffin cells of the rat adrenal medulla. In addition a few SP-immunoreactive nerve fibers with varicosities were found in the adrenal medulla of rats. They extended between small clusters of chromaffin cells and had their dotlike terminals around and within the cell clusters. The SP-immunoreactive nerve fibers were characterized by the presence of abundant small clear vesicles mixed with a few large granular vesicles; the immunoreactivity appeared in the latter, but was also perfused throughout the entire axoplasm. The nerve fibers formed synapses on nonimmunoreactive chromaffin cells. Judging from the presence of bundles of SP-immunoreactive nerve fibers penetrating the adrenal capsule and cortex as well as the absence of SP-immunoreactive ganglion cells in the medulla, the intramedullary SP-immunoreactive nerve fibers seem to be extrinsic in origin.

Calcitonin gene-related peptide (CGRP)-like immunoreactivity in scattered chromaffin cells and nerve fibers in the adrenal gland of rats

SummaryThe present immunohistochemical study reveals that a small number of chromaffin cells in the rat adrenal medulla exhibit CGRP-like immunoreactivity. All CGRP-immunoreactive cells were found to be chromaffin cells without noradrenaline fluorescence; from combined immunohistochemistry and fluorescence histochemistry we suggest that these are adrenaline cells. In addition, all CGRP-immunoreactive cells simultaneously exhibited NPY-like immunoreactivity. CGRP-chromaffin cells were characterized by abundant chromaffin granules with round cores in which the immunoreactive material was densely localized. These findings suggest the co-existence of CGRP, NPY and adrenaline within the chromaffin granules in a substantial number of chromaffin cells.Thicker and thinner nerve bundles, which included CGRP-immunoreactive nerve fibers, with or without varicosities, penetrated the adrenal capsule. Most of them passed through the cortex and entered the medulla directly, whereas others were distributed in subcapsular regions and among the cortical cells of the zona glomerulosa. Here the CGRP-fibers were in close contact with cortical cells. A few of the fibers supplying the cortex extended further into the medulla. The CGRP-immunoreactive fibers in the medulla were traced among and within small clusters of chromaffin cells and around ganglion cells. The CGRP-fibers were directly apposed to both CGRP-positive and negative chromaffin cells, as well as to ganglion cells. Immunoreactive fibers, which could not be found close to blood vessels, were characterized by the presence of numerous small clear vesicles mixed with a few large granular vesicles. The immunoreactive material was localized in the large granular vesicles and also in the axoplasm. Since no ganglion cells with CGRP-like immunoreactivity were found in the adrenal gland, the CGRP-fibers are regarded as extrinsic in origin. In double-immunofluorescence staining for CGRP and SP, all the SP-immunoreactive fibers corresponded to CGRP-immunoreactive ones in the adrenal gland. This suggests that CGRP-positive fibers in the adrenal gland may be derived from the spinal ganglia, as has been demonstrated with regard to the SP-nerve fibers.

An immuno-electron-microscopic study of the localization of VIP-like immunoreactivity in the adrenal gland of the rat

SummaryVIP-like immunoreactivity was revealed in a few chromaffin cells, medullary ganglion cells and a plexus of varicose nerve fibers in the superficial cortex and single varicose fibers in the juxtamedullary cortex and the medulla of the rat adrenal gland. VIP-like immunoreactive chromaffin cells were polygonal in shape without any distinct cytoplasmic processes and they appeared solitarily. Their cytoplasm contained abundant granular vesicles having a round core and the immunoreactive material was localized to the granular core. VIP-immunoreactive ganglion cells were multipolar and had large intracytoplasmic vacuoles. The immunoreactive material was localized not only in a few granular vesicles but also diffusely throughout the axoplasm. VIP-immunoreactive varicose nerve fibers in the superficial cortex were characterized by abundant small clear vesicles and some large granular vesicles, while those in the juxtamedullary cortex and medulla and the ganglionic processes were characterized by abundant large clear vesicles, as well as the same vesicular elements as contained in the nerves in the superficial cortex. The immunoreactive material was localized on the granular cores and diffusely in the axoplasm in both nerves. Based on the similarity and difference in the composition of the vesicles contained in individual nerves, it is likely that the VIP-immunoreactive nerve fibers in the medulla and the juxtamedullary cortex are derived from the medullary VIP-ganglion cells, while those in the superficial cortex are of extrinsic origin. The immunoreactive nerve fibers in both the cortex and the medulla were often in direct contact with cortical cells and chromaffin cells, where no membrane specializations were formed. The immunoreactive nerve fibers were sometimes associated with the smooth muscle cells and pericytes of small blood vessels in the superficial cortex. In addition they were often seen in close apposition to the fenestrated endothelial cells in the cortex and the medulla, only a common basal lamina intervening. Several possible mechanisms by which VIP may exert its effect in the adrenal gland are discussed.

Neuropeptide tyrosine-like immunoreactive nerve fibers in the carotid body chemoreceptor of rats.

Abundant NPY-immunoreactive nerve fibers were found throughout the parenchyma of the rat carotid body. They were in close proximity to smooth muscle cells and pericytes of small blood vessels intervening a narrow interstitial space of 80-150 nm. No immunoreactive nerve fibers were associated with chief or sustentacular cells. After removing the superior cervical ganglion, no immunoreactive nerve fibers were seen in the ipsilateral carotid body and the immunoreactive nerve fibers remained intact in the carotid body after cutting the ipsilateral superior cervical sympathetic trunk. The NPY-immunoreactive nerve fibers are therefore considered to be postganglionic sympathetic noradrenergic nerves.

Discrete distribution of cholinergic and vasoactive intestinal polypeptidergic amacrine cells in the rat retina

The distribution and fine structure of cholinergic amacrine cells of the rat retina were observed using monoclonal anti-choline acetyltransferase (ChAT) antibody. The ChAT-immunoreactive cholinergic cells were located in the innermost zone of the inner nuclear layer and in the outer zone of the ganglion cell layer, and they formed two distinct bands in the inner plexiform layer. The ChAT-immunoreactive materials were diffusely localized throughout the cytoplasm except for the nucleus, mitochondria, Golgi apparatus and the interior of the endoplasmic reticulum and vesicular components. The sequential immunostaining of one and the same section with both the ChAT antibody and the antiserum against vasoactive intestinal polypeptide (VIP) revealed clearly that the cholinergic amacrine cells are distinct from the VIP-immunoreactive amacrine cells.

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.

Immunohistochemical study on met-enkephalin-arg-gly-leu-like immunoreactive nerve fibers in the rat adrenal medulla

Met-enkephalin-Arg-Gly-Leu-like immunoreactivity was revealed in many nerve fibers as well as in chromaffin cells in the rat adrenal medulla. The immunoreactive nerve fibers were seen among and around chromaffin cells in the forms of punctate structures or varicose processes and they were characterized by numerous small clear vesicles mixed with several large granular vesicles. The nerve fibers formed synaptic contacts with both Met-enkephalin-Arg-Gly-Leu-like immunoreactive and non-immunoreactive chromaffin cells. The immunoreactive material in the nerves was generally confined to the granular cores. The present findings suggest that preproenkephalin A and its derivatives are produced in adrenal afferents which may be preganglionic cholinergic, and that they may play a significant role in the function of adrenal chromaffin cells.

Fine-structural localization of neuropeptide tyrosine (NPY)-like immunoreactivity in the neuronal somata of colchicine-pretreated celiac ganglia of rats

SummaryIn colchicine-pretreated cells of sympathetic ganglia, intensely NPY-immunoreactive material was localized within vacuoles and vesicles of the disorganized, widely dispersed Golgi apparatus. Intensely positive large granular vesicles, which are known to be one of major storage sites of various peptides in the autonomic nerve endings, were essentially unobserved in the perikaryal cytoplasm. The present finding provides evidence that one pool of NPY-like immunoreactivity is localized in the Golgi apparatus of colchicine-pretreated as well as normal sympathetic ganglion cells. It is also clear that visualization of NPY-immunoreactive somata by colchicine-pretreatment in the sympathetic ganglia is due to the accumulation of the neuropeptide in the disorganized Golgi stacks instead of increased amount of the large granular vesicles containing NPY.

Occurrence of myelin-associated glycoprotein (MAG)-like immunoreactivity in some nervous, endocrine, and immune-related cells of the rat. An immunohistochemical study.

The occurrence and distribution of myelin-associated glycoprotein (MAG)-like immunoreactivity was investigated in the rat using a polyclonal antibody to MAG purified from rat brain. In the nervous system, MAG immunoreactivity was found in the periaxonal portion of the myelinated fibers and in a small number of oligodendroglia in the cortex, hippocampus, and the spinal cord. The sheath of Schwann cells in unmyelinated fibers and satellite cells in the spinal ganglia were also immunoreactive for MAG. In the endocrine system, the noradrenaline-containing cells in the adrenal medulla and some endocrine cells in the duodenum showed MAG immunoreactivity. In the immune system, numerous reticular cells with slender cytoplasmic processes, which formed a dense network, were immunopositive for MAG within the germinal center in the lymph nodes and spleen. In the thymus, a number of epithelial reticular cells within the medulla showed variation in staining intensity. These findings provide new information on the wide distribution of MAG immunoreactivity in the nervous, endocrine, and immune systems, and may contribute to the further understanding of the biological roles of this protein.

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).