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Content available remote Novel nociceptin analogues.
A series of new nociceptin analogues containing cysteine was tested for their nociceptive effects in tail-flick test on mice after icv injection. The cysteines were introduced in order to get irreversibly binding analogues based on the assumption that the cysteines in the ligand can interact with the cysteines from the receptor to form an S-S bridge. In vivo tests revealed that Cys1-nociceptin (1-13)-NH2 (Cys1-NC) is an antagonist, whereas Cys7-NC is an agonist. Gly1,[Phe(p-NO2)]4-NC was less active indicating that the antagonist properties of Cys1-NC are associated with the presence of the sulfhydryl group of cysteine. The analogues D-Cys2 and Cys3 were also almost inactive.
An enhanced microdialysis method for neuropeptides is described and some prelimi­nary results of this novel approach are presented. The enhancement is achieved by adding a vehicle (solid support) to the perfusion fluid in order to increase the diffusion coefficient across the membrane and efficiently transport the analytes towards the de­tector. The microdialysis samples are desalted and then analyzed on an electrospray ionization orthogonal time-of-flight mass spectrometer. The preliminary results show major increase in signal when comparing this new approach of microdialysis with or­dinary microdialysis.
Introduction and objective. As the autonomic nervous system (ANS) dysfunction is present in course of many disorders, an objective assessment of the ANS function is very important. In practice, the assessment is difficult, and based rather on indirect analysis of autonomically-controlled cardiovascular reflexes, than on direct recording of activity of central or peripheral autonomic structures. The aim of our paper was to discuss briefly current, clinical and scientific ANS investigations, as well as possible future methods of autonomic activity evaluation. A brief description of the state of knowledge. The review presents a short outline of autonomic function assessments based on clinical autonomic tests (e.g. “Ewing’s battery”) and discusses the heart rate variability (HRV) study, as currently popular and widespread option of analysis of the ANS activity. Other, complementary methods, including the baroreceptor sensitivity testing, microneurography or plasma norepinephrine measurement were also mentioned. The article also provides premises related to the determination of selected neuropeptides in plasma or saliva as an innovative concept of autonomic activity assessment. Summary. The available, clinical, non-invasive methods used for assessment of the ANS function are still relatively sparse and, in fact, a surrogate for direct ANS assessment. New methods of autonomic tension determination are still needed that would allow a more complete and reliable assessment. Reports of potential new laboratory markers of the ANS activity (NPY and VIP assay) bring some hope.
Content available remote Cortistatin and pituitary hormone secretion in rat
Cortistatin (CST), a novel neuropeptide, shows high structural homology and functional resemblance with somatostatin. CST binds with high affinity to all somatostatin receptors, and contrary to somatostatin, is also able to bind with MrgX2 and GH secretagogue receptor of ghrelin (GHS-R1) receptors. The aim of the present investigation was to evaluate in vivo the effect of peripheral administration of cortistatin on pituitary hormone release in comparison with somatostatin (SS) treatment. Adult male rats used in the experiment, were given peripheral injection of cortistatin, somatostatin or vehicle. Blood was withdrawn 60 and 120 minutes thereafter. We found short lasting significant decrease of GH concentration as a result of administration of CST and SS when compared with saline injected controls. Prolactin levels were increased 60 min after cortistatin but not to somatostatin injection. There was no effect of CST on both LH and FSH concentration; however, SS administration influenced gonadotropin secretion. We conclude that cortistatin play a regulatory role in pituitary secretion. Moreover, some differences have been found when compared cortistatin to somatostatin. Thus, when analyzing the mechanism of cortistatin activity it is worth to consider the effect of binding with receptors of somatostatin, specific receptor for CST (MrgX2) and GHS-R.
The existence of numerous neuropeptides in milk is well established. It is still unclear whether these neuropeptides are produced by the mammary gland or that the gland concentrates them from the general circulation. The aim of the study was to examine the possible localization of these neuropeptides in the mammary gland of guinea pigs at different physiological states by immunohistochemistry. Specific primers have been used for the somatostatin, vasoactive intestinal polypeptide, neurotensin, cholecystocinin, oxytocin, gonadotropin-releasing hormone and growth hormone. Among all the neuropeptides that have been examined gonadotropin-releasing hormone and somatostatin immunoreactivity were found in the mammary gland of lactating guinea pigs, but not in virgin and pregnant guinea pigs. Immunoreactivity was observed in the epithelial cells that compose the secretory alveoli and in the secretory material
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.
Single-, double- and triple-labelling immunohistochemistry were applied to study the distribution and neurochemical properties of cholinergic nerve fibres supplying the vas deferens in juvenile and adult pigs. Cholinergic nerves were identified using an antibody against choline acetyltransferase. Immunoblotting was applied to verify the specificity of choline acetyltransferase immunostaining. Western blotting performed on vas deferens tissue homogenates detected single immunoreactive protein with a molecular weight matching this of acetylcholine transferase (71,5 kDa). The majority of choline acetyltransferase-containing nerves innervating the organ are distributed in the lamina propria and coexpress immunoreactivities of up to 4 other biologically active substances including nitric oxide synthase (a marker of nitrergic structures) and neuropeptides, vasoactive intestinal polypeptide, neuropeptide Y and somatostatin. A comparison of data previously collected with the present results reveals that in the pig, neurochemical characteristics of choline acetyltransferase-containing pelvic neurons and nerve fibres supplying the vas deferens are very similar leading to conclusion that cholinergic innervation of the organ largely derives from pelvic ganglia.
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