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S Soinila

Publications and source records attributed to S Soinila.

At least 37 records · Page 2Linked to original sources
PubMed1997

Expression of nitric oxide synthase in hypothalamic nuclei following axonal injury or colchicine treatment.

Nitric oxide (NO) has recently gained much attention due to its apparently double-edged role in neuronal injury. This study was aimed at elucidating neuronal nitric oxide synthase (nNOS) expression in the brain after two types of injury, namely axonal transection and colchicine treatment. The neurosecretory hypothalamo-pituitary pathway served as a model for the reaction of central neurons to these two types of injury. Axonal transection, i.e., pituitary stalk section, resulted in a qualitative increase in NOS content in the supraoptic and paraventricular nuclei. In these nuclei, there was also an increase in the number of NOS-expressing neurons after the operation. Surprisingly, in the periventricular nucleus, a strong decrease in the number of NOS-positive magnocellular neurons was observed in the anterior part of the nucleus. Intracerebroventricular injection of colchicine resulted in an increase in the cell count in the paraventricular nucleus, while the other nuclei remained unchanged. Our results suggest that axonal injury results in an increase in nNOS expression in the major neurosecretory nuclei, while the periventricular nucleus shows the opposite reaction. Colchicine treatment has an effect similar to that of axotomy in the major neurosecretory nuclei, suggesting that an increase in NOS expression may be induced by interrupted axonal transport. In the periventricular nucleus, the decrease in the number of NOS-containing neurons suggests differences among hypothalamic NOS-containing neuron groups in response to neuronal injury.

Animals↗
PubMed1996

Superfluous expression of tryptophan hydroxylase in the zona incerta dopaminergic neurones.

We studied by double labelling the relationship between tryptophan hydroxylase-immunoreactive (TpOH-IR) neurones and A13 dopaminergic neurones in the zona incerta (ZI). TpOH-IR in the ZI was dramatically increased after colchicine treatment. While all of the TpOH-IR neurones exhibited also tyrosine hydroxylase-immunoreactivity (TH-IR), a marker of dopaminergic neurones, less than half (46%; n = 794) of the A13 TH-IR neurones in the ZI showed TpOH-IR. None of these neurones were immunoreactive, however, for serotonin either in intact animals or in animals pretreated with serotonin precursor L-tryptophan and the monoamine oxidase inhibitor pargyline. Thus, the neurones of the A13 dopaminergic group in the ZI expressing TpOH are unable to synthesize serotonin. These findings support the idea that neurones may superfluously express non-functional transmitter synthesizing enzymes, in this case TpOH, and suggest that expression of an enzyme synthesizing a certain transmitter does not necessarily confirm the corresponding transmitter phenotype.

Animals↗
PubMed1996

Pituitary gland receives both central and peripheral neuropeptide Y innervation.

Neuropeptide Y (NPY)-containing neural projections to the rat pituitary gland were studied by combining NPY immunohistochemistry with retrograde tracing with Fluorogold as well as central and peripheral denervations. Numerous pituitary-projecting, i.e. Fluorogold-labelled, neurons in the superior cervical ganglion, as well as in the hypothalamic magnocellular nuclei were NPY-immunoreactive (NPY-IR). In contrast, no other hypothalamic NPY-IR neurons, e.g. in the arcuate nucleus or the preoptic area, were observed to be projecting into the pituitary. Within the posterior lobe of the pituitary gland two morphologically distinct NPY-IR fiber populations were discovered, namely thinner parenchymal terminals, distinct from the neurosecretory terminals, and thicker, perivascular fibers. Neurosecretory nerve terminals, in contrast, were devoid of NPY-IR, being consistent with the previous reports on their sensitivity to osmotic stimulation. On the other hand, the anterior and intermediate lobes contained no NPY-IR fibers. Bilateral extirpation of the superior cervical ganglion resulted in disappearance of the perivascular NPY-IR fibers leaving the parenchymal NPY-IR fibers unaffected, while transection of the pituitary stalk abolished all of the parenchymal NPY-IR neurons, leaving the perivascular fibers unaffected. These findings together with the observed colocalization of tyrosine hydroxylase and NPY in the posterior lobe perivascular fibers indicated that they are sympathetic nerve endings. The thin parenchymal terminals, instead, are suggested to stem from central sources other than hypothalamus. Our findings indicate that the pituitary gland receives NPY-containing innervation from at least three distinct sources, and NPY may thus affect pituitary functions in various ways, such as blood flow and vasopressin release.

Animals↗
PubMed1996

Nitric oxide synthase in the autonomic and sensory ganglia innervating the submandibular salivary gland.

This article reviews the neuroanatomical studies on the distribution of nitric oxide synthase (NOS) in neurons and nerve fibers innervating the submandibular gland. Specificity of NADPH-diaphorase activity as a histochemical marker of neuronal NOS is discussed in light of corresponding NOS immunoreactivity. Anatomical data suggest that nitric oxide may affect neural regulation of the submandibular gland through both sympathetic, parasympathetic and sensory divisions of the autonomic nervous system. NOS-containing nerve terminals in the gland parenchyme are mainly vascular and either parasympathetic and/or sensory in nature, while sympathetic terminals lack NOS. Most postganglionic parasympathetic neurons are intensely NOS-immunoreactive. Some of the preganglionic parasympathetic neurons show vague reactivity, while their terminals in the submandibular ganglia stain heavily. The postganglionic sympathetic neurons normally show only barely visible reactivity, while manipulations interrupting axonal continuity increase neuronal NOS content. A subpopulation of the preganglionic sympathetic neurons and their terminals are intensely reactive. The observations summarized here suggest that nitric oxide participates in the control of blood flow through the gland, while direct effect on secretion is unlikely.

Animals↗
PubMed1996

Axonal transport of nitric oxide synthase in autonomic nerves.

By using mechanical nerve ligation or nerve pinch technique, we provide evidence that nitric oxide synthase (NOS) is transported in the preganglionic sympathetic axons, while postganglionic axons lack NOS transport. This finding corroborates the preganglionic sympathetic terminal as the site of NO synthesis, which is known to affect ganglionic transmission. Both vasoactive intestinal polypeptide (VIP) and substance P (SP) containing neurons of the nodose ganglion transport NOS in their axons. These results therefore suggest that NOergic innervation of autonomically innervated tissues is of parasympathetic and/or sensory, rather than sympathetic, origin.

Animals↗
PubMed1996

Substance P- and vasoactive intestinal polypeptide-immunoreactive innervation in normal and inflamed pouches after restorative proctocolectomy for ulcerative colitis.

Recent studies suggest that the intestinal polypeptides substance P (SP) and vasoactive intestinal polypeptide (VIP) play a role in the bowel inflammatory processes. The aim of this study was to evaluate the distribution of SP and VIP immunoreactivities in the ileal pouch of the patients with ulcerative colitis (UC). Thirty-six patients underwent clinical evaluation, endoscopy, and histological examinations. Samples were taken from normal ileum (N = 9), ileum of UC patients (N = 9), normal ileal pouch (N = 9) and pouchitis (N = 9). SP- and VIP-containing nerve fibers were visualized in sections processed for immunofluorescence microscopy. The number and intensity of SP and VIP immunoreactivities were subjected to quantitative scoring. On samples from all groups lamina propria contained fibers showing bright immunofluorescence for SP and VIP. The number and intensity of SP immunoreactive nerve fibers were markedly increased in pouchitis as compared to normal pouch (P < 0.005), to ileum of UC patients (P < 0.001), and to normal ileum (P < 0.05). The number and intensity of VIP-immunoreactive nerve fibers in the lamina propria were markedly increased in pouchitis patients and in those having a normal pouch as compared to pooled values of ileum of UC patients and normal ileum (P < 0.05). The results suggest that SP, which may play a role in mediating inflammatory processes, is increased in pouchitis and that VIP, which may contribute to the regulation of intestinal motility, is increased in the pouch.

Adult↗
PubMed1996

Substance P--an underlying factor for pouchitis? Prospective study of substance P- and vasoactive intestinal polypeptide-immunoreactive innervation and mast cells.

Recent studies suggest that substance P (SP), vasoactive intestinal polypeptide (VIP), and mast cells play a role in inflammatory processes of the bowel. The aim of this study was to evaluate the distribution of SP and VIP immunoreactivities and to count mast cells in the ileal pouch of patients, who had pouchitis after restorative proctocolectomy performed for treatment of ulcerative colitis (UC), and to compare the findings in the same patients after a follow-up period. Nine patients with pouchitis underwent clinical evaluation, endoscopy of the pouch, and histological examination, which were repeated after the follow-up period of 14 months on average. The number and intensity of SP- and VIP-immunoreactive nerve fibers were visualized by immunofluorescence microscopy and subjected to quantitative scoring, and the number of mast cells per unit area was counted. The results were compared to the histological findings and the clinical status. Lamina propria contained fibers showing bright immunofluorescence for SP and VIP. The mean fluorescence intensity score of SP-immunoreactive nerve fibers in the lamina propria remained similar after the follow-up period (2.99 +/- 0.79 and 2.06 +/- 0.82, NS). SP-immunoreactive innervation correlated with the grade of acute (R2 = 0.5396, P = 0.0242) and chronic inflammation (R2 = 0.4561, P = 0.0459), while SP and VIP immunoreactivity, mast cell count, and histological changes did not correlate with the clinical status. The present study demonstrates an increase in the density of SP-immunoreactive nerve fibers in inflamed ileal pouch mucosa of clinically asymptomatic pouchitis patients. These results raise the possibility of therapeutic interference of SP-related processes in treatment of pouchitis.

Adult↗
PubMed1996

Effect of monensin on secretory granules and basal beta-endorphin secretion in the melanotroph of the rat pituitary.

The effect of monensin on the Golgi complex, formation of secretory granules and basal beta-endorphin secretion in cultured melanotrophs from the rat pituitary was studied. Earlier studies on the effect of monensin on regulated secretion have generally showed only minor effects on secretory granules. The initial (within 5 min) effect of monensin on the melanotroph was the appearance of large vacuoles at the trans-side of the thiamine pyrophosphatase-positive trans-most Golgi cisternae. This was associated with a dose-dependent inhibition of the condensation of electron-dense secretory products. After 1 h of treatment with 1 microM monensin the Golgi stack was completely vacuolized. At the same time mature secretory granules were enlarged to severalfold their original size, and after 4 h of treatment secretory granules were no longer observed. Despite the marked effects on granule formation and mature secretory granules monensin did not affect the basal release of beta-endorphin-immunoreactive material during continued incubation for up to 4 h, indicating that basal peptide secretion can bypass the monensin block.

Animals↗
PubMed1996

Putative neuroendocrine cells in the Aplysia cerebral ganglion.

We report on a special population of cells in the Aplysia cerebral ganglion that are characterized by several features compatible with neuroendocrine function. These cells can be recognized in living ganglia by their small size, white color and their typical distribution as a compact cluster in the central medial region of the dorsal ganglion surface. Upon intracellular recording, these cells generate action potentials of relatively long duration (about 25 ms), as compared with the faster action potentials of larger white cells or of non-white cells (about 4 ms). Intracellular injection of the small white cells with Lucifer yellow after recording revealed a dual projection area: single cells have one process which branches extensively into many varicose terminals as it courses through the neuropil, and then sends varicose terminals to the vascular sheath at the periphery of the ganglion. In cryostat sections, these cells were specifically characterized by their content of large granules, the staining characteristics of which distinguish them from lipochondria or lysosomes. Their ability to bind fluorochromes nonspecifically is of particular importance for the interpretation of histochemical localization studies based on immunofluorescence techniques.

Animals↗
PubMed1996

Nitric oxide-synthesizing neurons originating at several different levels innervate rat penis.

While the crucial role of neurally produced nitric oxide in mediating penile erection is well established, the understanding of the peripheral neuroanatomy of the nitric oxide-ergic pathways is still incomplete. This study was designed to elucidate further the distribution of nitric oxide synthase, and its relation to the distribution of neuropeptides and tyrosine hydroxylase in all penis-projecting neural pathways. A triple-labelling technique was employed, with the retrograde tracer Fluoro Gold combined with neuropeptide immunohistochemistry and nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry, a marker of nitric oxide synthase. The presence within the penis of scattered nerve cell bodies exhibiting NADPH-diaphorase activity was revealed. Most (76%) of the penis-projecting neurons in the major pelvic ganglion exhibited NADPH-diaphorase activity and immunoreactivity to vasoactive intestinal peptide, while none of them contained tyrosine hydroxylase. Sympathetic paravertebral postganglionic neurons, in turn, contained tyrosine hydroxylase, but did not exhibit NADPH-diaphorase activity. In the afferent, sensory neurons projecting to the penis from the dorsal root ganglia, NADPH-diaphorase activity coexisted with immunoreactivity to both substance P (8%) and calcitonin gene-related peptide (26%). Preganglionic neurons originating in the spinal cord intermediolateral column at the thoracolumbar level T11-L3 terminated, not only in the major pelvic ganglion, but also within the penis. The majority (81%) of the penis-projecting neurons exhibited NADPH-diaphorase activity. The results indicate that the rat penis receives several different nitric oxide-ergic neural projections. It is therefore possible that nitric oxide affects penile erection at several neuronal levels.

Animals↗
PubMed1996

Dose-dependent effects of chloroquine on secretory granule formation in the melanotroph.

Chloroquine diverts secretory peptides from the regulated to the constitutive secretory pathway. The exact site and mechanism of the effect are not known. We studied the effect of increasing doses of chloroquine on the morphology of cultured melanotrophs from the rat pituitary. 40 microM chloroquine for 2 h, which perturbs intracellular pH gradients in melanotrophs without affecting secretion, caused swelling of a subpopulation of immature secretory granules. 200 microM chloroquine for 2 h, which diverts secretory peptides from the regulated to the constitutive pathway in the AtT-20 cell line, caused pronounced swelling of immature secretory granules, vacuolization of the trans-Golgi region and the appearance of myeloid bodies and multivesicular bodies in the cytoplasm. Golgi stacks were retained and Golgi cisternae only slightly dilated at both chloroquine concentrations. Mature secretory granules were not affected. Cationized ferritin was internalized and transported to the trans-Golgi region in the presence of 40 microM chloroquine while 200 microM chloroquine arrested internalised ferritin in peripheral multivesicular bodies. The study shows a heterogeneous effect of lower doses of chloroquine on immature secretory granules, providing a tool for studies on the relationships between condensation, acidification and peptide processing during granule formation. Chloroquine of 200 microM caused morphological changes typical for chloroquine toxicity and arrest of endocytic traffic.

Animals↗
PubMed1995

Direct nitric oxide-containing innervation from the rat spinal cord to the penis.

Nitric oxide synthase (NOS)-immunoreactive pathways to the rat penis were studied by combining retrograde tracing by Fluorogold with NOS immunohistochemistry. Injection of the tracer into the penile shaft resulted in Fluorogold labelling in a vast number of NOS-immunoreactive neurons in the major pelvic ganglion. In addition, some neurons in the spinal cord intermediolateral column consistently contained Fluorogold label in the upper lumbar levels. Most of these neurons were also NOS-immunoreactive. These findings suggest that the sympathetic preganglionic, NOS-containing neurons project to the penis, and they may participate in nitric oxide-mediated penile erection.

Adrenergic Fibers↗
PubMed1995

Co-localization of NADPH diaphorase reactivity and vasoactive intestinal polypeptide in human colon.

Nitric oxide-containing nervous structures were localized in the human colon using NADPH diaphorase activity and nitric oxide synthase immunoreactivity. We found some, solitary NADPH diaphorase-reactive and nitric oxide synthase-immunoreactive neurons in the submucous plexus, while the myenteric plexus contained several neurons, often arranged in clusters, and nerve fibers showing these markers. The circular muscle layer contained a dense plexus of NADPH diaphorase-reactive nerves, which was greater than that in the longitudinal muscle layer. We report on co-localization of NADPH diaphorase activity and VIP immunoreactivity in several neurons of the myenteric ganglia. Such co-localization has not been reported previously for human colon. Localization of nitric oxide synthase and VIP in the myenteric plexus and in the nerves of circular muscle layer raises the possibility that nitric oxide contributes to the regulation of motility in the human colon.

Colectomy↗
PubMed1995

Dopaminergic periventriculo-hypophyseal nerves show tryptophan-hydroxylase immunoreactivity but lack serotonin synthesis.

Hypothalamic dopaminergic periventricular and arcuate nuclei are known to project to the pituitary gland and contain serotonin in their terminals. In order to elucidate the potential of these neurons to synthesize serotonin, we studied immunohistochemically the possible tryptophan hydroxylase content of periventriculo-hypophyseal neurons, identified by retrograde tracing from the pituitary gland. These neurons were found to contain tryptophan hydroxylase-immunoreactivity (TpOH-IR), which was enhanced after colchicine treatment. All of the TpOH-IR neurons contained tyrosine hydroxylase-immunoreactivity as well. However, none of them were immunoreactive for serotonin in either intact animals or in animals pretreated with serotonin precursor L-tryptophan and MAO inhibitor pargyline. Thus, neurons of the dopaminergic periventriculo-hypophyseal pathway express tryptophan hydroxylase, but are unable to synthesize serotonin. These findings (i) raise the possibility that, in these nerves, serotonin might serve a function other than regular synaptic transmission, and (ii) suggest that expression of an enzyme synthesizing certain transmitter does not necessarily confirm the corresponding transmitter phenotype of that neuron.

Animals↗
PubMed1995

5-Hydroxytryptamine-immunoreactive nerve fibers in the rat and porcine prevertebral sympathetic ganglia: effect of precursor loading and relation to catecholaminergic neurons.

Localization of 5-hydroxytryptamine immunoreactivity was studied in the rat coeliac-superior mesenteric ganglion complex and in the porcine superior and inferior mesenteric ganglia by the indirect immunofluorescence technique. In normal rats, only 5-hydroxytryptamine immunoreactive SIF cells were seen in the coeliac-superior mesenteric ganglion complex. In the rats, pretreated with a 5-hydroxytryptamine precursor, L-tryptophan, and with a monoamine oxidase inhibitor, nialamide, a large number of 5-hydroxytryptamine-immunoreactive nerve fiber terminals were detected. In normal porcine superior and inferior mesenteric ganglia, intense 5-hydroxytryptamine immunoreactivity was found in numerous nerve fibers which were located around tyrosine hydroxylase-immunoreactive principal neurons. The origin and function of these fibers are discussed.

Animals↗
PubMed1995

Colocalization of dopamine and serotonin in the rat pituitary gland and in the nuclei innervating it.

The nerve terminals in the intermediate and posterior lobes of the rat pituitary gland are reported to show colocalization of serotonin and tyrosine hydroxylase. This study examined the extent of this colocalization in the pituitary gland and in the nuclei considered to project to the pituitary. In the intermediate lobe, two types of nerve fibers were encountered, one containing serotonin (5-HT-IR) and tyrosine hydroxylase (TH-IR) immunoreactivities and the other showing 5-HT-IR only. Instead, there was no colocalization in the posterior lobe. In the hypothalamus, colchicine treatment with L-tryptophan and pargyline injections resulted in 5-HT-IR in some neurons in the dorsomedial, periventricular and arcuate nuclei, some of which in the arcuate and periventricular nuclei were also TH-IR. In the raphe nuclei no colocalization of 5-HT-IR and TH-IR was observed. Catecholamine neurotoxin, 6-hydroxydopamine, abolished the 5-HT-IR and dramatically reduced the TH-IR in the intermediate lobe nerve fibers. Both effects were prevented by cocaine, a monoamine uptake inhibitor, but not by fluoxetine, a specific serotonin uptake inhibitor. Serotonin neurotoxin p-chloroamphetamine (PCA) had no effect on intermediate lobe fibers, although it caused complete disappearance of 5-HT-IR from the posterior lobe nerve fibers. This effect was prevented by fluoxetine. Our results indicate, that colocalization of serotonin and TH observed in the intermediate lobe occurs both in the nerve terminals within the lobe and in some nuclei that innervate it. Furthermore, drug treatments suggest that serotonin in the intermediate lobe is localized in catecholaminergic fibers, which do not posses a specific serotonin uptake mechanism.

Animals↗
PubMed1995

Catecholamine-synthesizing enzymes in the rat stomach.

Local production of catecholamines in the stomach of the rat was studied by immunohistochemical demonstration of tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT), the enzymes catalyzing the formation of dopamine, noradrenaline and adrenaline, respectively. A rich innervation of TH- and DBH-immunoreactive nerve fibers was seen in the muscular layers and the myenteric plexus, in the submucosa and in the walls of submucosal blood vessels and in the lamina propria at the base of the epithelial layer. In addition, TH-, but not DBH-immunoreactive nerve fiber networks surrounding ganglion cells in the myenteric plexus were frequently observed, indicating dopaminergic preganglionic innervation of the myenteric plexus. In the oxyntic epithelium, single TH- and DBH-immunoreactive fibers extended in the strands of lamina propria as far as the middle portion of the gastric glands. A small population of single angulate cells in the oxyntic epithelium showed TH-, but not DBH-immunoreactivity. No specific PNMT immunoreactivity was observed.

Animals↗