Fine structure of neurons synthesizing vasoactive intestinal peptide in the human colon from patients with Hirschsprung's disease.

The fine structure of neuronal perikarya and processes containing VIP-like immunoreactive material in the colon of patients with Hirschsprung's disease was investigated by immunoelectron microscopy. No VIP-like immunoreactive terminals were found in Auerbach's plexus of the ganglionic segment. However, VIP-like immunoreactive preterminal axons were frequently found to make synaptic contact with both immunoreactive and non-immunoreactive elements within Meissner's plexus. Therefore, the function of the VIP neurons in Auerbach's plexus seems to differ from that in Meissner's plexus. In the oligoganglionic segment, there were a few VIP-like immunoreactive processes, but no VIP-like immunoreactive synaptic formations. VIP-like immunoreactive processes were rarely encountered in the aganglionic segment. In both the oligo- and aganglionic segments, bowel relaxation is considered to be disturbed due to the lack of synaptic contacts of VIP-like immunoreactive neurons with other neuronal components.

Light and electron microscopic study of somatostatin-like immunoreactive neurons in rat hippocampus.

The distribution and fine structure of somatostatin-like immunoreactive neurons in rat hippocampus and gyrus dentatus were investigated by light and electron microscopic immunocytochemistry. Somatostatin-like immunoreactive neuronal perikarya and fibers could be visualized by using modified PAP immunocytochemistry. Immunoreactive neurons were selectively localized in the stratum orience of the hippocampus and hilar region of the gyrus dentatus, however, immunoreactive neurons were also sparsely observed throughout hippocampal formation. Somatostatin-like immunoreactive varicosities were abundantly distributed in the stratum pyramidale and some of them were considered to terminate on the pyramidal cells. Somatostatin-like immunoreactive neurons in the hippocampal formation generally contained many mitochondria, well-developed rough surfaced endoplasmic reticulum (rER), polysomes and some dense granules. Immunoreactivity was observed especially in the dense granules and membrane of rER. Pre- and post-synaptic elements of somatostatin-like immunoreactive neurons were detected throughout the hippocampal formation.

Light and electron microscopic immunocytochemistry of beta-endorphin/beta-LPH-like immunoreactive neurons in the arcuate nucleus and surrounding areas of the rat hypothalamus.

beta-Endorphin/beta-LPH-like immunoreactive neurons in the hypothalamic arcuate nucleus and its surrounding areas were visualized by light and electron microscopic immunocytochemistry. Immunoreactive processes were found in the vicinity of the pia mater, in the lateral part of the external layer of the median eminence and near the lateral wall of the third ventricle. Neuronal perikarya contained immunoreactive dense granules as well as developed cell organellae. They received neuronal inputs from other neurons through axoplasmic and axodendritic synapses. Immunoreactive neuronal processes containing dense granules and mitochondria were found as preterminal elements on non-immunoreactive neuronal soma and dendrites. Immunoreactive processes also make intimate contact with capillaries in the arcuate nucleus near the median eminence.

Immunohistochemical investigations of gut hormones in the colon of patients with Hirschsprung's disease.

The distributions of gut hormones in the colon of Hirschsprung's disease were investigated by the peroxidase-antiperoxidase (PAP) immunohistochemical method. Three colonic segments (ganglionic, oligoganglionic, and aganglionic) were stained by the unlabeled antibody enzyme method. The immunoreactivity of vasoactive intestinal polypeptide (VIP) was found to be reduced in the oligoganglionic and aganglionic segments. Antisera to substance P and met-enkephalin demonstrated immunoreactive cells and fibers in the ganglionic segment, whereas these cells and fibers were almost completely absent in the oligoganglionic and aganglionic segments. A similar distribution was seen for the mucosal endocrine cells with somatostatin immunoreactivity. Antisera to neurotensin, motilin, bombesin, and cholecystokinin revealed no immunoreactivity in the normal colon or the three segments. The differences in these peptides between normal and impaired colonal segments may be one of the causes of colon constriction in Hirschsprung's disease.

Light and electron microscopic immunocytochemistry of neurotensin-like immunoreactive neurons in the rat hypothalamus.

Neurotensin-like immunoreactive neuronal perikarya, fibers and terminals in the rat hypothalamus, particularly in the arcuate nucleus, the paraventricular nucleus and the median eminence, were investigated by light and electron microscopic immunocytochemistry. The main distributional areas of immunoreactive neuronal perikarya were found to be the arcuate nucleus, the periventricular nucleus and the paraventricular nucleus by light microscopic immunocytochemistry. Immunoreactive neuronal perikarya showed a characteristic distributional pattern in the arcuate nucleus. In the paraventricular nucleus they were distributed in both the magnocellular and parvocellular portions. A large number of immunoreactive terminals were observed throughout the external layer of the median eminence, particularly its lateral portion. A moderate number of immunoreactive terminals were also observed in the internal layer of the median eminence. By electron microscopic immunocytochemistry immunoreactive neuronal perikarya both in the arcuate and paraventricular nuclei showed generally well-developed cell organelles such as mitochondria, r-ER, and Golgi complex. In addition, immunoreactive dense granules were dispersed throughout the perikarya. A large number of immunoreactive terminals containing immunoreactive dense granules, clear vesicles and mitochondria were observed in the vicinity of pericapillary spaces of the external layer of the median eminence. This observation strongly suggests that neurotensin-like immunoreactive substance is released into the portal capillaries.

The fine structures of the VIP-like immunoreactive neurons in the cat hypothalamus.

The fine structures of the VIP-like immunoreactive neurons in the suprachiasmatic nucleus (SCN) and the arcuate nucleus ( ARN ) of the cat hypothalamus were investigated by electron microscopic immunocytochemistry. The VIP-like immunoreactive soma and fibers could be successfully visualized by a modified PAP method. VIP-like immunoreactive neurons in both nuclei contained immunoreactive rER, Golgi complexes and many immunoreactive granules, as well as well developed mitochondria. VIP-like immunoreactive synaptic endings with synaptic membrane specialization of Gray's type I and II were found in the SCN. Moreover VIP-like immunoreactive preterminal elements that made synaptic contact with VIP-like immunoreactive neuronal soma were also detected. On the other hand, it was difficult to detect typical preterminal endings with immunoreactivity in the ARN ; however, VIP-like immunoreactive processes in contact with the basement membrane of the capillaries were observed. These observations indicate that VIP-like immunoreactive neurons in the SCN act as intrinsic neurons and are involved in neuroendocrine function in ARN .

Morphological survey of neurotensin-like immunoreactive neurons in the hypothalamus.

Neurotensin-like immunoreactive neuronal perikarya, fibers and terminals in in the rat hypothalamus were investigated by light and electron microscopic immunocytochemistry. Distributional density and pattern of these elements were clarified. Fine structure of immunoreactive neuronal perikarya with respect to development of cell organellae and immunoreactive dense granules was also elucidated. Features of immunoreactive processes, dendrites and preterminal axons were examined electron microscopically. In addition to the above findings by light and electron microscopic immunocytochemistry, we examined the coexistence of dopamine and neurotensin-like immunoreactive substances in these same neurons in the arcuate and periventricular nuclei. This was proved by the application of fluorescence histochemistry and immunocytochemistry on the same sections. Moreover, we speculated that the ascending noradrenergic neurons influence the neurotensin immunoreactive neurons in the paraventricular nucleus since a marked decrease in the number of neurotensin-like immunoreactive neuronal perikarya was observed after transection of ascending noradrenergic pathway.

Distribution of the VIP-like immunoreactive neurons in the cat central nervous system.

Immunohistochemical topographic localization of the vasoactive intestinal polypeptide (VIP)-like immunoreactive neurons in the cat brain was investigated using a peroxidase anti-peroxidase technique. VIP-like immunoreactive neurons were mainly localized in the cerebral cortex, limbic cortex, hypothalamic nuclei; suprachiasmatic nucleus, supraoptic nucleus, paraventricular nucleus, periventricular nucleus and arcuate nucleus, and in the midbrain; such as the central grey and the raphe nucleus. It was demonstrated that VIP-like immunoreactive neurons were widely distributed in the cat brain, particularly in the hypothalamus, compared with those of the rat and mouse; though whether these differences were species-related or due to differences in the physiological conditions remains to be determined. This is the first report of VIP neuronal perikarya in the arcuate nucleus of mammalian species, although these cells are present in the arcuate nucleus of birds.