Biomedical subjects

S Soinila

Publications and source records attributed to S Soinila.

At least 19 recordsLinked to original sources

PubMed2001

Interaction of calcitonin gene-related peptide (CGRP), substance P (SP) and conventional autonomic agonists in rat submandibular salivary peroxidase release in vitro.

Our previous immunohistochemical studies reveal that several neuropeptides, such as substance P and calcitonin gene-related peptide, innervate the major salivary glands of the mouse, rat and human. The aim of the study was to clarify their interactions by measuring their effects alone or with conventional autonomic agonists (carbachol, phenylephrine and isoproterenol) on peroxidase secretion of incubated submandibular gland slices. Calcitonin gene-related peptide evoked significant increase in peroxidase activity of the secretion only when used at 10(-5) M concentration, while substance P evoked significant, dose-dependent increase at much lower concentrations (10(-10) M). Adrenergic and cholinergic agonists enhanced peroxidase activity. Interestingly, substance P inhibited both phenylephrine and isoproterenol induced increase in peroxidase activity. Calcitonin gene-related peptide did not affect the inhibition caused by substance P. Our results demonstrate that in the salivary gland tissue substance P alone or in conjunction with adrenergic agonists result in opposing secretory responses with the doses used in vitro. Conversely, the response mediated by adrenergic receptors may be critically affected by simultaneous occupation of substance P receptors.

Acetylcholine↗

PubMed2001

Changes in distribution of three isoforms of nitric oxide synthase in ulcerative colitis.

BACKGROUND: Nitric oxide (NO) has an important role both in normal physiology and pathological events of the colon. Our aim was to study possible changes of the three nitric oxide synthases in ulcerative colitis (UC). METHODS: Tissue samples from normal colon and least and moderately affected regions of ulcerative colitis colon were obtained at surgery and immunostained for NOS-1, NOS-2, NOS-3, and GAP-43, a marker of nerve fibers. Quantitative analysis of NOS-1 immunoreactivity was performed on the circular muscle layer. RESULTS: NOS-1-immunoreactive fibers in the muscularis mucosae disappeared in least affected and moderately affected UC colon. Quantitative analysis of NOS-1-immunoreactive nerve fibers in the circular muscle showed no differences between normal and diseased colon. NOS-2 immunoreactivity appeared apically in the epithelial cells. In normal colon some specimens showed immunoreactivity in lower parts of crypts. NOS-2 immunoreactivity increased according to the severity of UC. NOS-3 immunoreactivity was exclusively localized in the vascular endothelium. The difference in NOS-3 staining intensity between the lamina propria and submucosa observed in normal tissue disappeared in moderately affected UC colon. The number of NOS-3-immunoreactive vascular profiles increased in the lamina propria of UC colon. CONCLUSIONS: All three NOS isoforms show specific changes in UC colon.

Aged↗

PubMed2000

Nitric oxide synthase immunoreactivity in the rat hippocampus after status epilepticus induced by perforant pathway stimulation.

Nitric oxide has recently been implicated in mediation of neuronal excitotoxicity and damage. This study aimed at elucidating the changes in the expression of neuronal isoform of nitric oxide synthase (nNOS) in the hippocampus after status epilepticus induced by perforant pathway stimulation. nNOS-immunoreactivity (nNOS-ir) and neuronal damage, assessed by silver staining, were evaluated separately in different hippocampal subfields 2 weeks after induction of status epilepticus. Perforant pathway stimulation resulted in an increase in the number of nNOS-immunoreactive neurons in the stratum radiatum of the CA1 and CA3 subfields of the hippocampus proper, and the hilus of the dentate gyrus. The morphology and distribution of the nNOS-ir neurons resembled that of interneurons. No correlation of the number of nNOS-ir neurons to the neuronal damage score was observed. Our results suggest that status epilepticus provokes a de novo expression of nNOS protein, and the nNOS expressing neurons may be selectively resistant to epileptic brain injury.

Animals↗

PubMed2000

Muscle membrane-skeleton protein changes and histopathological characterization of muscle-eye-brain disease.

Muscle-eye-brain disease belongs to congenital muscular dystrophies with central nervous system abnormalities. The etiology of MEB is still unknown, but abnormal immunoreactivity for laminin-2 has been reported. To evaluate disease progression in muscle tissue, 32 biopsy specimens from 17 muscle-eye-brain patients were analysed. The samples of four patients were studied by immunohistochemical techniques and by quantitative Western blotting. The samples showed a great variation in the muscle pathology. Regenerative fibers and mild fiber size variation were present in over 60%. At infancy, necrotic and regenerative fibers were common, while fat infiltration was the most prominent finding in the age group over five years. In quantitative studies, the amount of laminin alpha 2 chain was clearly reduced to 10-20% of normal. In contrast, laminin beta 2 chain was overexpressed in the Western blotting studies. These findings may reflect a yet unidentified primary disturbance in the basement membrane composition and function.

Adolescent↗

PubMed2000

Monensin and hypo-osmolar medium cause calcium-independent beta-endorphin secretion from melanotropes.

Monensin has been shown to cause nonexocytotic release of catecholamines from adrenal medullary and PC12 cells. We examined the effect of monensin on peptide secretion with cultured melanotropes from the rat pituitary as a model. 1 microM monensin caused an immediate, transient increase in beta-endorphin secretion. The effect was still seen in a calcium-free medium, but was totally abolished in a sodium-free medium. Intracellular calcium concentration was measured with Fura 2: no increase was observed during monensin stimulation. Hypo-osmolar medium mimicked the effect of monensin, causing a 12-fold transient increase in beta-endorphin secretion. This effect was not abolished in either calcium-free or sodium-free medium. No increase in the number of exocytotic figures captured by tannic acid incubation was observed during 5 min of incubation with 1 microM monensin or hypo-somolar medium. We thus show that monensin causes beta-endorphin secretion from the melanotrope and that this effect is due to sodium influx and resultant cell swelling. The calcium independency and lack of increase of exocytotic figures suggest that swelling-induced secretion is nonexocytotic, possibly via transient exocytotic pore opening.

Animals↗

PubMed1999

Age-related augmentation of the dehydration-induced increase in the supraoptic nitric oxide synthase activity in rats.

Hypothalamic supraoptic nucleus (SON) neurons express nitric oxide synthase (NOS) in an activity-dependent manner. In the present study, the effect of aging on the NOS expression of the SON neurons, as detected by nicotinamide adenine dinucleotide phosphate-diaphorase activity, was studied under normal conditions and under dehydration stress induced by salt loading. In the control rats, the number of stained neurons did not differ between the two age groups. Dehydration resulted in an increase in both the number of staining neurons and in the staining intensity in both 2- and 14-16-month-old rats. Furthermore, dehydration-induced NOS expression was significantly higher in the older animals. The results suggest that the response to dehydration, as indicated by increased NOS activity in the supraoptic nucleus, is enhanced in the aging rat.

Age Factors↗

PubMed1999

Inducible expression of tryptophan hydroxylase without serotonin synthesis in hypothalamic dopaminergic neurons.

In the present study we have further studied the previous findings that rat hypothalamic dopaminergic neuronal cell groups may express tryptophan hydroxylase (TpH), the serotonin synthesizing enzyme, without a detectable serotonin synthesis. Chemical and mechanical neuronal injuries, namely colchicine treatment and axonal transection, respectively, were performed, and distributions of neurons exhibiting immunoreactivity for TpH and/or tyrosine hydroxylase (TH), the dopamine synthesizing enzyme, were analyzed throughout the hypothalamic periventricular and arcuate nuclei. After colchicine treatment there was a statistically significant 87% (P = 0,01) increase in the number of TpH expressing neurons, while TH expression remained essentially similar. Axonal transection resulted also in a statistically significant 131% (P < 0,01) increase in the number of TpH expressing neurons, while TH expression was not significantly altered. All TpH expression coexisted with TH expression, and the induction of TpH expression by neuronal injuries occurred evenly throughout the rostrocaudal length of the territory studied. A possible serotonin synthesis by TpH was examined by giving drugs that increase brain serotonin synthesis, but no immunohistochemically detectable serotonin synthesis could be found in any of the TpH expressing neurons. Finally the possibility was studied that the relative shortage of the cofactor tetrahydrobiopterin would limit serotonin synthesis. However, an administration of tetrahydrobiopterin did not result in detectable serotonin synthesis in these neurons. Taken together these results suggest that dopaminergic neurons in the hypothalamic periventricular and arcuate nuclei are able to express TpH, this expression is induced after neuronal injury, and this induction occurs similarly throughout the territories studied. TpH expression occurs independently of TH expression, and the newly expressed TpH appears not to synthesize serotonin, regardless of pharmacological pretreatments. Thus, our findings (i) support the idea that neurons may possess inducible expression of nonfunctional transmitter-synthesizing enzymes, in this case TpH, and (ii) suggest that expression of an enzyme synthesizing a certain transmitter may not necessarily imply the corresponding transmitter phenotype.

Animals↗

PubMed1999

Quantitative comparison of growth-associated protein GAP-43, neuron-specific enolase, and protein gene product 9.5 as neuronal markers in mature human intestine.

This study was performed to compare GAP-43, PGP 9.5, synaptophysin, and NSE as neuronal markers in the human intestine. GAP-43-immunoreactive nerve fibers were abundant in all layers of the ileum and colon. GAP-43 partially co-localized partially with every neuropeptide (VIP, substance P, galanin, enkephalin) studied. All neuropeptide-immunoreactive fibers also showed GAP-43 reactivity. By blind visual estimation, the numbers of GAP-43-immunoreactive fibers in the lamina propria were greater than those of PGP 9.5, synaptophysin, or NSE. In the muscle layer, visual estimation indicated that the density of GAP-43-immunoreactive fiber profiles was slightly greater than that of the others. The number and intensity of GAP-43-, PGP 9.5-, and NSE-immunoreactive fibers were estimated in sections of normal human colon and ileum using computerized morphometry. In the colon, the numbers of GAP-43-immunoreactive nerve profiles per unit area and their size and intensity were significantly greater than the values for PGP and NSE. A similar trend was observed in the ileum. Neuronal somata lacked or showed only weak GAP-43 immunoreactivity, variable PGP 9.5 immunoreactivity, no synaptophysin immunoreactivity, and moderate to strong NSE immunoreactivity. We conclude that GAP-43 is the superior marker of nerve fibers in the human intestine, whereas NSE is the marker of choice for neuronal somata. (J Histochem Cytochem 47:1405-1415, 1999)

Biomarkers↗

PubMed1998

Colchicine differentially induces the expressions of nitric oxide synthases in central and peripheral catecholaminergic neurons.

This study was aimed at elucidating differences in nerve injury induced expression of nitric oxide synthases (NOS) between the peripheral and central catecholaminergic neurons. Colchicine was used to disrupt chemically the neuronal cytoskeletal integrity. A marked increase in the expression of neuronal NOS-IR and NADPH-diaphorase activity, a marker of neuronal NOS (nNOS), was seen in distinct populations of post-ganglionic sympathetic neurons of the superior cervical ganglion after intraganglionic colchicine injection. Similarly, immunoreactivity for the inducible form of NOS (iNOS) was induced in some sympathetic neuron somata. However, this immunoreactivity did not coincide with nNOS-IR. In contrast to the sympathetic neurons, hypothalamic arcuate and periventricular dopaminergic neurons did not show NOS-IR or NADPH-DA either in intact animals or in animals treated with an intracerebroventricular injection of colchicine. Immunoreactivity for the inducible form of NOS revealed no neuronal staining in the hypothalamic neurons in either group, while a large number of glia-resembling cells around the third ventricle showed slight expression of iNOS-IR. The present results show that expression of both neuronal and inducible forms of NOS may be induced by colchicine in some catecholaminergic neurons. It is suggested that these inductions are specific to certain catecholaminergic neuronal systems, like the sympathetic neurons, rather than a general property of catecholaminergic neurons.

Animals↗

PubMed1998

The ontogenic appearance of tyrosine hydroxylase-, serotonin-, gamma-aminobutyric acid-, calcitonin gene-related peptide-, substance P-, and synaptophysin-immunoreactivity in rat pituitary gland.

The initial appearance of tyrosine hydroxylase (TH)-, serotonin (5-HT)-, gamma-aminobutyric acid (GABA)-, calcitonin gene-related peptide- (CGRP), substance P-, and synaptophysin-immunoreactivity in the rat pituitary gland, and in the related brain regions was investigated. Several groups of TH-immunoreactive neurons were first detected in the brain stem on day E17, and in the hypothalamus on day E18, followed by TH-immunoreactivity in the median eminence and infundibulum on E19-E20. TH-positive fibers appeared in the posterior lobe on day E20 and in the intermediate lobe on day P0. 5-HT-immunoreactivity was first detected on day E17 in neurons and nerve fibers in the brain stem and in the median eminence, respectively. On day E18, a few 5-HT-immunoreactive fibers were detected in the posterior lobe of the pituitary, although they were consistently seen in the infundibulum from day E19. In newborn rats, some 5-HT-immunoreactive fibers, but no neurons, were seen in the hypothalamus. GABA immunoreactivity appeared on day E17 in several nerve fibers of the infundibulum and the posterior lobe. Some neurons in the cortex and ventral hypothalamus transiently expressed GABA-immunoreactivity on day E17. In newborn rats, a plexus of GABA-immunoreactive fibers was detected for the first time in the intermediate lobe. No CGRP-immunoreactive fibers could be detected in the prenatal pituitary. On day P10, CGRP-immunoreactive fibers were first observed in the anterior lobe. Later their number considerably increased, while only sporadic fibers could be found in the intermediate or posterior lobes. No substance P-immunoreactivity could be detected in any of the lobes in the embryonic or developing postnatal rat pituitary, instead the adult anterior lobe occasionally showed some substance P-immunoreactive fibers. Synaptophysin-immunoreactivity was first detected in the posterior lobe on day E20, followed shortly by its expression in the intermediate lobe in newborn rats. The time course of GABA and 5-HT expression revealed in the present study suggests that these transmitters, which are initially expressed in the developing pituitary clearly before synaptic maturation, may act as trophic molecules during the prenatal period.

Animals↗

PubMed1998

Nerve terminals containing neuropeptides decrease in number after massive proximal small bowel resection in the piglet.

The aim of this study was to evaluate possible changes in the neuropeptide innervation pattern of the remaining porcine ileum following 75% proximal resection of the small intestine. Three-month-old piglets were operated on and two months postoperatively full-thickness specimens of the proximal part of the distal ileum wall were taken. Age-matched 3- and 5-month-old unoperated piglets were used as controls. The number and intensity of VIP-, galanin-, enkephalin-, substance P-, and somatostatin-containing nerve fibers were estimated in sections processed for immunofluorescence microscopy and subjected to quantitative scoring. The VIP-, galanin-, and enkephalin-immunoreactive fibers of the circular muscle layer and villi were also quantitated by computer-assisted morphometry. The number and intensity of VIP-immunoreactive fibers in the mucosa and circular muscle layer markedly decreased after resection as compared to 3-month-old and 5-month-old controls (P < 0.05). The galanin immunoreactivity index decreased significantly after resection in the circular muscle layer as compared to both control groups (P < 0.05). The increase in the number of enkephalin-immunoreactive nerve fibers that normally occurred from 3 to 5 months of age was inhibited by the resection. We were not able to see any differences in somatostatin or substance P immunoreactivity between the groups. The results suggest that massive resection induces significant changes in the neuropeptide-containing innervation of the remaining small intestine. These findings are compatible with altered motor activity and mucosa function in the remain intestine.

Adaptation, Physiological↗

PubMed1998

Serotonin is not synthesized, but specifically transported in the neurons of the hypothalamic dorsomedial nucleus.

A small group of neurons in the hypothalamic dorsomedial nucleus (DMN) have been reported to contain serotonin after pharmacological treatments enhancing brain serotonin levels. This study aimed at elucidating whether these neurons are able to synthesize serotonin de novo, and whether they possess a specific serotonin transport mechanism. Serotonin content in these neurons was raised by administration of L-tryptophan and pargyline. Double immunostaining for serotonin and tryptophan hydroxylase (TpOH), the serotonin synthesizing enzyme, revealed that none of the serotonin-containing neuronal somata expressed TpOH. Intracerebroventricular colchicine treatment did not result in TpOH-IR in these neurons. Fluoxetine, a specific serotonin transport inhibitor, prevented the accumulation of serotonin in these neurons. The present results thus indicate that the serotonin-containing DMN neurons are not able to synthesize serotonin. Instead, they take up exogenous serotonin via a specific serotonin transport mechanism. As serotonin and DMN are associated with various physiological functions, such as regulation of food intake and modulation of fear and anxiety, the mechanisms revealed in the present study may participate in these clinically important brain functions.

Animals↗

PubMed1998

The concept of chemical neurotransmission--variations on the theme.

The present concept of chemical neurotransmission occurring purely through synaptic transmission has dominated neurobiological thinking for about the last 40 years. According to this conventional view neurotransmitters are substances that are synthesized within the neurones, liberated into the synaptic cleft after stimulation of the nerve, and that finally elicit a biologically plausible response in the postsynaptic target cell or the nerve terminal itself. This concept undoubtedly comprises the main body of interneuronal chemical signalling. However, a large amount of evidence, obtained during the last two decades, suggests that there are a number of parallel mechanisms, which may essentially participate in neuronal signalling, or at least modulate it. Thus, the recent progress of research has provided the following compelling evidence: 1) a large variety of substances, some of them synthesized in non-neuronal cells, actually participate actively in neuronal signalling; 2) functional connections in brain are not determined by the synaptic connections only; 3) glial cells have an active and fundamental role in signal transmission; and 4) the signalling properties and mechanisms of each neurone are constantly under functional and structural regulation. The aim of this review is to present shortly some of the central concepts and/or mechanisms that have risen during the last two decades. Also the functional and/or clinical relevance of these mechanisms is addressed briefly.

Animals↗

PubMed1997

Commercial mouse and human nerve growth factors contain nerve growth factor prohormone isoforms.

Highly sensitive chemiluminescence immunoblot analysis was utilized to examine the purity of mouse 2.5S-, beta- and 7S nerve growth factors as well as that of recombinant human beta-nerve growth factor obtained from commercial vendors. Three polyclonal antisera and two monoclonal antibodies to 13 kDa nerve growth factor (2.5S NGF and beta-NGF) were employed for assessing the purity of each preparation. In addition, polyclonal antisera against two prepro-NGF specific domains were used for immunoblotting analysis to ascertain the identity of high molecular weight nerve growth factor immunoreactive proteins as prohormones. Both the mouse and human NGF preparations contained 53 and 60 kDa immunoreactive proteins. Of these, the mouse 60 kDa and the human 53 kDa proteins strongly immunoreacted with both prepro-nerve growth factor specific domain antibodies suggesting that they are two NGF prohormone isoforms. In addition, both the mouse and human nerve growth factor preparations contained proteins that were immunoreactive to polyclonal antisera and monoclonal antibodies to mouse 2.5S and/or beta-NGF. High molecular weight aggregates of prohormones were also observed in mouse and human nerve growth factor samples. In summary, none of the ten NGF samples examined were pure as stated. Our study cautions investigators in the field to be aware of the presence of nerve growth factor prohormones and other proteins in various mouse and human nerve growth factors sold commercially.

Animals↗

PubMed1997

Increase of catechol-O-methyltransferase activity in rat brain microglia after intrastriatal infusion of fluorocitrate, a glial toxin.

Striatal catechol-O-methyltransferase (COMT), monoamine oxidase B (MAO-B; an astroglial enzyme), alkaline phosphodiesterase I (PDE; a microglia/macrophage marker) and tyrosine hydroxylase (TH; catecholaminergic neuron marker) activities were analyzed biochemically 1-3 days after infusion of fluorocitrate, an astrocyte damaging agent. Astrocytes, microglia and neurons were stained immunohistochemically with specific antibodies (against glial fibrillary acidic protein, OX-42 and TH, respectively) and with COMT antiserum. Three days after fluorocitrate infusion the activity of MAO-B was reduced, whereas COMT and PDE activities were increased. The elevation of COMT immunoreactivity co-localized to microglial cells, but not to astrocytes. In conclusion, this is the first report indicating that microglia contains COMT activity which may be increased in pathological conditions.

Animals↗

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↗