Tomohiro Matsuyama

Histaminergic axons in the neostriatum and cerebral cortex of the rat: a correlated light and electron microscopic immunocytochemical study using histidine decar☐ylase as a marker

Histaminergic nerve fibers and their axonal varicosities in the neostriatum and cerebral cortex were light and electronmicroscopically examined by means of peroxidase-antiperoxidase immunocytochemistry with histidine decarboxylase (HDC) as a marker. A majority of HDC-like immunoreactive axonal varicosities observed in serial thin sections for electron microscopy exhibited no synaptic contacts in either the neostriatum or cerebral cortex. The remaining small proportion of immunoreactive axonal varicosities formed synaptic contacts with non-immunoreactive dendritic shafts and spines.

Glutamate-like immunoreactive structures in primary sensory neurons in the rat detected by a specific antiserum against glutamate.

SummaryWe found that large cells in the dorsal root and trigeminal ganglia contained glutamate-like immunoreactivity. Immunoreactive neurons were not detected in the superior cervical or pterygopalatine ganglia. These findings indicated that glutamate is a neurotransmitter or neuromodulator of large cells of sensory ganglia.

Two distinct calcitonin gene-related peptide-containing peripheral nervous systems: Distribution and quantitative differences between the iris and cerebral artery with special reference to substance P

The present study first shows that calcitonin gene-related peptide(CGRP)-like immunoreactive (CGRPI) nerve fibers in the cerebral arteries contained substance P (SP) and originated from small- to medium-sized CGRPI cells exhibiting SP immunoreactivity (SPI) in the trigeminal ganglion. The iris contained CGRPI/SPI-costorage nerve fibers and many CGRPI fibers lacking SPI. These fibers originated from large CGRPI cells lacking SPI in the trigeminal ganglion. The heterogenous subpopulations of CGRPI fibers in the iris suggest that CGRP is involved in a variety of functions in this structure.

Overall distribution of vasoactive intestinal polypeptide-containing nerves on the wall of cerebral arteries: An immunohistochemical study using whole-mounts

The overall distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactivity on the wall of the cerebral arteries, including its 3-dimensional profile, was investigated by means of the indirect immunofluorescence method using flat-mounts. VIP-immunoreactive fibers run spirally on the wall of the cerebral arteries. On the wall of the large arteries, such as the vertebral artery, basilar artery, internal carotid artery, within and/or without the circle of Willis, posterior and anterior communicating arteries, proximal parts of anterior, mid and posterior cerebral arteries, these fibers are richly distributed and show a dense grid-like appearance. The highest density was identified on the wall of the anterior cerebral artery, internal carotid artery and anterior communicating artery, while the lowest density was on the posterior communicating artery. On the other hand, on the walls of the branches of these arteries or along distal parts of the anterior, mid and posterior cerebral arteries, the number of VIP-immunoreactive fibers decreased markedly.

Origins and distribution of calcitonin gene-related peptide-containing nerves in the wall of the cerebral arteries of the guinea pig with special reference to the coexistence with substance P

The origins and overall distribution of calcitonin gene-related peptide-like immunoreactivity (CGRPI) in the wall of the cerebral arteries were investigated in the guinea pig by using whole-mounts. Two types of CGRPI fibers were seen; one forming dense fiber bands, located among the periadventitial nerves, and the other forming a meshwork. CGRPI fibers in the periadventitial nerves often leave these nerves to form a meshwork, of a density that varies according to the diameter or location of the blood vessel. The present study showed that CGRPI fibers in the walls of the carotid arterial system originated from the trigeminal ganglion, and those in the vertebrobasilar arterial system from other origins besides the trigeminal ganglion. We also examined the coexistence of this peptide with substance P-like immunoreactive (SPI) structures in a single neuron system. Double staining immunocytochemistry showed that the patterns of the running of CGRPI and SPI fibers in the wall of the cerebral arteries were similar, and this method also demonstrated the presence of neurons containing both CGRPI and SPI structures in single cells of the trigeminal ganglion, which is the major origin of these fibers in the cerebral arteries.

Differential Effect of Cerebral Ischemia on Monoamine Content of Discrete Brain Regions of the Mongolian Gerbil (Meriones unguiculatus)

Abstract: The effect of bilateral cerebral ischemia on noradrenaline, dopamine, and serotonin concentrations in six brain regions (i.e., the cerebral cortex, striatum, hippocampus, midbrain‐diencephalon, cerebellum, and pons‐medulla oblongata) was examined in the gerbil stroke model. The relative changes in regional cerebral blood flow after bilateral common carotid occlusion were also assessed using the radioactive microsphere technique. At 1 h after bilateral carotid occlusion, a significant decrease of monoamine concentration was observed in the cerebral cortex, striatum, hippocampus, and midbrain‐diencephalon whereas no significant change was detected in the cerebellum and pons‐medulla oblongata. The fall in NA content was most prominent in the cerebral cortex and hippocampus and percentage reductions of dopamine and serotonin were greatest in the striatum and cerebral cortex, respectively. These results suggest that the monoamine neurons in various brain regions might have different vulnerabilities to ischemic insult and show no evidence of transtentorial diaschisis.

Why are infant gerbils more resistant than adults to cerebral infarction after carotid ligation

Younger gerbils have been found to be more resistant than adults to cerebral infarction after carotid ligation. In this study, the perfused cerebral area after bilateral common carotid occlusion was evaluated in infant, young, and adult Mongolian gerbils by the carbon black perfusion method to assess the existence and significance of collateral blood vessels between the vertebrobasilar and carotid circulations. Nineteen gerbils were divided into three groups (i.e., infant, young and adult gerbils aged 3–4, 5–7, and 10–17 weeks, respectively). After bilateral common carotid artery occlusion, carbon black was injected directly into the left ventricle by cardiac puncture through the closed thorax. In five of eight infant gerbils, the whole brain was perfused by carbon black, while in the remaining three, only the cerebellum and brainstem were stained well, and marked bilateral cerebral pallor was observed. On the other hand, carbon black did not perfuse the brain region supplied by the carotid arteries, both in young and adult gerbils (11 animals in total). These results suggest that infant gerbils might have a more highly developed network of collateral blood vessels between the vertebrobasilar and carotid circulations, and the existence of such a significant network might be the basis for the fact that infant gerbils are resistant to cerebral infarction following carotid ligation. We propose that gerbils should be used as a stroke model only when they are 5 weeks old or older.

Immunocytochemical analysis of [Met5]enkephalin-Arg6-Gly7-Leu8 immunoreactive structures in the rat superior cervical ganglion.

Indirect immunofluorescence and immunoelectron microscopy were employed to analyze the enkephalinergic systems in the rat superior cervical ganglion (SCG). These systems were identified using specific antiserum against [Met5]Enkephalin-Arg6-Gly7-Leu8 (ENK-8), a peptide which is derived only from proenkephalin A. Abundant ENK-8 like immunoreactive (ENK-8-LI) neurons and fibers were observed in the SCG, but their distribution patterns were heterogenous; ENK-8-LI neurons were localized preferentially in the caudal two-thirds of the SCG, while immunoreactive fibers were found to be distributed more densely in the rostral one-third than in the remaining part of the SCG. Most of the ENK-8-LI neurons were large and had ultrastructural features resembling those of principal cells, some were identified electron microscopically as small intensely fluorescent (SIF) cells. ENK-8-LI fibers were varicose in appearance and surrounded the perikarya of neurons. Since most of these fibers were not detected after experimental decentralization of the SCG and since ENK-8-LI terminals were seen to contain small lucent vesicles, most of the former were thought to be preganglionic fibers. Immunoreactive fibers mainly formed synaptic contacts with the dendrites of non-immunoreactive principal cells, but a small proportion of ENK-8-LI principal cells also received synaptic input from them. Occasionally, immunoreactive fibers formed synapses with the processes or the soma of both ENK-8-LI and non-immunoreactive SIF cells. On the basis of these findings, we conclude that: (1) preganglionic ENK-8-LI fibers terminate mainly on the principal cells, which are devoid of ENK-8-LI structures; (2) the majority of ENK-8-LI neurons are principal cells, while the remainder are SIF cells; (3) inputs to these cells mainly involve structures lacking ENK-8 immunoreactivity; and (4) there are, however, a small number of ENK-8-LI preganglionic fibers which terminate on ENK-8-LI principal cells and SIF cells.

Dual innervation of substance P-containing neuron system in the wall of the cerebral arteries

The present study has shown the presence of substance P-like immunoreactive (SPI) fiber plexuses both in the carotid and vertebrobasilar systems in the Mongolian gerbil, suggesting that the origins of SPI fibers in these two systems differ. The present study further demonstrated in the guinea pig, using experimental manipulations, the dual origin of SPI fibers in the cerebral arteries; one from the trigeminal ganglion (TG) that mainly innervates the carotid system, and the other that separates from the TG and mainly innervates the vertebrobasilar system.

Two discrete enkephalinergic neuron systems in the superior cervical ganglion of the guinea pig: an immunoelectron microscopic study

Leucine-enkephalin (L-ENK)-like immunoreactive (L-ENKI) structures in the superior cervical ganglion (SCG) were first examined by using immunoelectron microscopy. L-ENKI neurons formed cell clusters and were small. They were filled with large granular or agranular vesicles and small electron lucent vesicles, and had nuclei that lacked a nucleolus. Since these morphological characteristics are identical to those of the small intensely fluorescent (SIF) cells, L-ENKI cells seemed to be a kind of SIF cell. Two types of L-ENKI fibers were identified, a large type filled with large granular or agranular vesicles and a small type filled with small electron lucent vesicles. The large fibers were located near the L-ENKI perikarya and often could be traced directly to the soma. These fibers remained intact after decentralization of the SCG. These findings indicate that the large L-ENKI fibers are processes of L-ENKI SIF cells. The fibers showed a close apposition to the blood vessels and rarely formed synaptic contact with dendrites of the principal cells. On the other hand, the small L-ENKI fibers were found to originate outside the SCG, because they disappeared after decentralization of the SCG. These L-ENKI fibers frequently formed synaptic contact with the dendrites of the principal cells. Thus, the present study demonstrated the presence of two discrete L-ENKI neuron systems in the SCG of the guinea pig, one an intrinsic SIF system and the other an extrinsic L-ENKI system.