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Substance P (SP) infused into the third cerebral ventricle blocks spontaneous ovulation in female rats, probably through catecholaminergic neurons. The studies presented in this paper were undertaken to investigate whether SP exerts its suppressing effect on ovulation in 6-hydroxydopamine (6-OHDA) pretreated female rats. After 8-12 days following 6-OHDA pretreatment female rats were infused, on the day of proestrus, with vehicle and all animals were found to ovulate or with a solution containing 5 nmol of SP and 89% of female rats were then found to ovulate. In the group pretreated with vehicle and subsequently infused with SP, ovulation was found to occurr only in 25% of animals. The obtained results indicate that spontaneous ovulation in 6-OHDA-pretreated female rats cannot be blocked by i. c. v. administration of SP, and it may be concluded that SP exerts its suppressing effect through the monoaminergic neurons.
Expression of substance-P in human neurons of trigeminal ganglia has been investigated by immunohistochemistry and morphometry. These neurons constituted 12.8% to 32.6% of the total neuronal population in the trigeminal ganglia. Substance-P positive granulations were concentrated around the nucleus, distributed focally in neuroplasm or dispersed over the neuroplasm. Morphometric analysis has indicated the presence of three populations of SP-positive cells: small, medium-sized and large. The results suggest a functional differentiation on the level of the first neurons of the afferent path of the stomatognatic system. Substance-P is likely to play a role in the transmission not only of nociceptive impulses but also of those involved in the mechano-functional stimulation of system activities.
The aim of this study was to examine a morphological picture of guinea pig skin that had been injected with neuropeptides (NPS)2 - substance P (SP) and guinea pig vasoactive intestinal peptide (VIP) - to elucidate their local influence. Routine histological stainings were performed, together with immunohistochemical reactions for T cells and for macrophages. In the deeper layers of the skin, T cell and macrophagic infiltrations were observed. The intensity of these changes was greater 24 hours after injections than that observed at the third hour of the experiment.
The aim of this study was to determine histotopography and age-related changes of immunoreactive substance P (SP-IR) nerve plexus in dog cornea. In this research corneas of three groups of dogs of different age were used: young (2-3 months), adult (1-3 years) and old (8 and more years). Immunohistochemical demonstration of SP was performed on 40 um serial free-floating corneal sections cut parallel to the corneal surface. Results showed that SP-IR nerve plexus of dog cornea was formed by thick (21.9-73 μm diameter), medium (7.3-21.8 μm diameter) and thin (2.19-7.2 um diameter) nerve bundles and varicose or smooth nerve fibers branching into terminals. From limbus SP-IR thick nerve bundles ran radially through superficial and intermediate layers of stroma to the central part of cornea. Thick nerve bundles split into medium ones in central and pericentral parts of cornea. They branched repeatedly forming nerve plexus of stroma. Thin nerve bundles located in subepithelium, superficial and intermediate layers of stroma split from thick and medium bundles. Nerve fibres branched from thin bundles, curved and joined with each other, forming a network of various forms. The highest amount of nerve fibres was observed in corneal epithelium and subepithelium layer. The nerve bundles of young dogs were smaller in diameter than those of adults and old ones. With age the density of nerve fibres and thin bundles decreased in corneal epithelium and subepithelium layer. The density of medium and thick bundles in superficial and intermediate stroma was similar in dogs of all ages. No nerve plexus elements were noticed in stromal deep layer and endothelium in dogs of all ages.
The presence of choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), somatostatin (SOM), galanin (GAL), substance P (SP) and calcitonin gene-related peptide (CGRP) was studied in neurons and nerve fibers of the porcine otic ganglion. ChAT-positive neurons were very numerous while VAChT-positive nerve cells were moderate in number. The number of neurons containing NPY and VIP was lower and those containing SOM, GAL, SP or CGRP were observed as scarce, or single nerve cells. The above mentioned substances (except SOM) were present in nerve fibers of the ganglion. ChAT- and VAChT-positive nerve fibers were numerous, while the number of nerve terminals containing NPY, VIP and SP was lower. GAL- and CGRP-positive nerve fibers were scarce.
Gorąca A., Traczyk W. Z.: The lack of influence of some neuropeptides present in the posterior pituitary lobe on the frequncy of spontaneous contraction of the sisolated heart auricle. Acta Physiol. Pol. 1940, 4 (6): Investigations have shown the presence of a cardiodepressant factor in the fluid incubating the posterior pituitary lobe “in situ”, which decreased contraction frequency of the isolated heart auricle (Acta Physiol. Pol., 1984, 35: 460-468). The influence on the spontaneuos contraction frequency of the isolated heart auricle of the following synthetic neuropeptides was determined: substance P, leu-enkephalin, met-enke- phalin, angiotensin II, arg-vasopressin, oxytocin, delta sleep-inducing peptide and atrial natriuretic factor. It was found that the investigated neuropeptides had no effect on the contraction frequency of the isolated auricle of the heart right atrium of two-day-old rat in a concentration from 2.1 × 10⁻⁷ to 1 × 10⁻³ mol/1 in the bathing medium and it was concluded that their biological properties differ from the cardiodepressant factor.
The aim of the present study was to investigate the effect of peptide NK-1 and NK-2 receptors agonists and antagonists (and their natural ligands, i.e., substance P and neurokinin A) on the oxytocin (OT) secretion from the rat neurohypophysis into the blood. Intracerebroventricular (icv) injection of substance P (SP) or highly selective NK-1 receptor agonist - [(Sar9,Met(O2)11)-Substance P] - significantly stimulated the OT secretion from the rat neurohypophysis into the general circulation. After icv injection of the NK-1 receptor antagonist - [(Tyr6,D-Phe7,D-His9)-Substance P (6-11)] - the blood plasma OT concentration was significantly lower, when compared to vehicle-injected animals. On the other hand, the icv administered neurokinin A (NKA) and the NK-2 receptor agonist - [(ß-Ala8)-Neurokinin A (4-10)] - were essentially inactive in modifying OT secretion. However, such injection of the NK-2 receptor antagonist - [(Tyr5,D-Trp6,8,9,Lys-NH210)-Neurokinin A (4-10)] - was found to diminish the blood plasma hormone concentration, when compared to vehicle-injected animals. The neurohypophysial content of OT was decreased in NKA-treated rats, but neither the NK-2 receptor agonist nor antagonist were able to affect the OT output from the rat posterior pituitary. The hypothalamic levels of OT were not modified by any of the studied peptides. The present data strongly indicate a major role for the tachykinin NK-1 receptor in SP- and/or NKA-dependent regulation of OT secretion from the rat neurohypophysis into the blood.
Present investigations were undertaken to study the influence of peptide NK-1 and NK-2 receptor agonists and antagonists as well as substance P and neurokinin A (the natural ligands for these tachykinin receptors) on oxytocin (OT) release from isolated rat hypothalamo-neurohypophysial (H-N) system as well as to determine whether the tachykinin NK-1 and/or NK-2 receptors contribute to the response of oxytocinergic neurons to melatonin. The results show, for the first time, that highly selective NK-1 receptor agonist, i.e., [Sar9,Met(O2)11]-Substance P, enhances while the NK-1 receptor antagonist (Tyr6,D-Phe7,D-His9)-Substance P (6-11) - sendide - diminishes significantly OT secretion; the latter peptide was also found to antagonize the substance P-induced hormone release from isolated rat H-N system, when used at the concentration of 10-7 M/L. Melatonin significantly inhibited basal and substance P-stimulated OT secretion. Neurokinin A and the NK-2 receptor selective agonist (ß-Ala8)-Neurokinin A (4-10) as well as the NK-2 receptor antagonist (Tyr5,D-Trp6,8,9, Lys-NH210)-Neurokinin A (4-10) were essentially inactive in modifying OT release from the rat H-N system in vitro. The present data indicate a distinct role for tachykinin NK-1 (rather than NK-2) receptor in tachykinin-mediated regulation of OT secretion from the rat H-N system. Under present experimental conditions, however, a role of respective tachykinin receptors in the response of oxytocinergic neurons to melatonin has not been found.
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