The Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine

Background: The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT. Objectives: To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS) in different regions of the rat intestine. Materials and Methods: Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists. Results: EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist) and granisetron up to 10.0 µM, GR113808 (a 5-HT4 receptor antagonist), methysergide and ritanserin up to 1.0 µM, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 µM (a 5-HT6 receptor antagonist) there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 µM (5-HT7 receptor antagonist) induced a greater contractile response to EFS at 0.4 Hz only in the duodenum. Conclusions: The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 µM did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions. Keywords: Electric Stimulation Therapy; Serotonin 5-HT1 Receptor Antagonists; Intestine, Smal

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

Collaborative study on influenza vaccine clinical trial serology - part 2: reproducibility study.

A collaborative study was run by the Biological Standardisation Programme (BSP) under the aegis of the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe) and the European Union (EU) Commission, to address the issue of the poor standardisation of serological assays used for the evaluation of seasonal influenza vaccines in Europe. The Phase 1 of the study focused on the compliance to Commitee for Human Medicinal Products (CHMP) criteria by 6 manufacturers and 5 public laboratories. It confirmed the poor inter-laboratory correlation of haemagglutination inhibition (HI) test results. Phase 2 consisted in a reproducibility study examining the impact of extended method standardisation and the use of reference sera on inter-laboratory variation. Six manufacturers and 5 public laboratories contributed HI results, while the 5 public laboratories also performed single radial haemolysis (SRH) tests on the same sample panels. Results showed that method standardisation failed to significantly improve the inter-laboratory variation. Correction for pre-vaccination titres (Beyer correction) was found to have limited effect to improve the bias constituted by the Protection Rate (PR) criterion. The reasons underlying the difficulty in standardization of HI and SRH tests are discussed and improved approaches for the compliance testing to CHMP criteria are suggested

Investigation of Serotonin Receptors in the Isolated Penile Bulb of Rats

The aim of this study was to investigate serotonin (5-HT) receptors in the penile bulb, which have been suggested to play a role in penile erection. Serotonin (10(-7)-3 x 10(-4) M) contracted penile bulbs in a concentration-dependent manner. Ketanserin (5-HT2A antagonist, 10(-9)-10(-7) M) and prazosin (alpha(1)-adrenergic receptor blocker, 10(-9)-10(-7) M) suppressed the lower and upper parts of concentration -response curves to 5-HT, respectively. Guanethidine (adrenergic neuron blocker, 5 x 10(-5) M) reduced the responses to 5-HT at only 10(-4) and 3 x 10(-4) M concentrations. NAN-190 (5-HT1A antagonist, 10(-8), 10(-7) M) shifted the concentration-response curve to the right with a reduction in the maximum response to 5-HT. While ondansetron (5-HT3 antagonist, 10(-6)-10(-5) M) and GR55562 (5-HT1B/1D antagonist, 10(-6)-10(-5) M) had no effect on the concentration-response curve to 5-HT. The 5-HT1A agonist 8-OH-DPAT (10(-7)-3 x 10(-4) M) contracted penile bulbs in a concentration-dependent manner with a lower pD(2) value than that of 5-HT. Sumatriptan (5-HT1B/1D agonist, 10(-8)-10(-4) M) did not produce any contractile response in the penile bulbs. Prucalopride, a selective 5-HT4 agonist (R093877, 10(-7)-3 x 10(-4) M) produced concentration-dependent relaxation in penile bulbs contracted by phenylephrine (10(-5) M). 5-HT4 agonists cisapride (10(-7)-10(-4) M) and metoclopramide (10(-7)-3 x 10(-4) M) also relaxed the tissue, concentration-dependently. Selective 5-HT4 antagonists GR125487 (10(-6)-10(-5) M) and GR113808 (10(-6)-10(-5) M) slightly, but not significantly, decreased prucalopride- and cisapride-induced relaxation. Propranolol (beta-adrenergic receptor blocker, 10(-6)-10(-5) M) and L-NOARG (nitric oxide synthase inhibitor, 10(-4) M) had no effect on prucalopride- induced relaxation. These results suggest the existence of alpha(1)-adrenergic, 5-HT1A and 5-HT2A serotonergic receptors in the penile bulb of rats, which are responsible for 5-HT-induced contraction. Additionally, a serotonergic receptor resembling a 5-HT4-type plays a role in the relaxation. The latter receptor is activated by 5-HT4 agonists, but is not antagonized by 5-HT4 antagonists.WoSScopu

The Involvement of the Serotonergic Transmission System in Neonatal and Adult Rat Ileum Contractility Varies with Age

The relevance of age on serotonergic involvement in the control of alimentary contractility has not been pharmacologically described. Experiments were performed to investigate the effects of acetylcholine, atropine, 5-hydroxytryptamine (5-HT) and its related drugs on intestinal segments taken from the neonatal and adult ileum. 5-HT induced concentration-dependent contractions of ileum irrespective of age; however, these contractions were diminished by pretreatment with atropine only in neonatal tissues. In tissues taken from both the neonatal and adult ileum, methysergide (5-HT1/2/5–7 receptor antagonist), ritanserin (5-HT2 receptor antagonist), and RS23597-190/SB204070 (5-HT4 receptor antagonists) all differentially reduced 5-HT-induced contractions at a concentration 30 µmol/l in both neonatal and adult ileum. Combined treatments with ritanserin, granisetron, plus RS23597-190 reduced or abolished contraction responses induced in neonatal ileum by 5-HT. SB269970A (5-HT7 receptor antagonist) and WAY100635 (5-HT1A receptor antagonist) failed to influence contractile responses induced by 5-HT or 5-HT receptor agonists. Pretreatments with WAY100635 and SB267790A also had no influence on the contractile responses induced by 5-HT1A/7 receptor agonist, 5-CT, and 5-HT1A receptor agonist, 8-OH-DPAT, which itself failed to induce a measurable response. It is concluded that the 5-HT-induced contractions in segments taken from both the neonatal and adult rat ileum were mediated via 5-HT2 receptors, 5-HT3 receptors and 5-HT4 receptors. However, the effect of atropine on the neonatal rat intestine indicates that the mechanism of serotonergic involvement in ileal contractility is influenced by age