NADPH-diaphorase expression in the rat jejunum after intestinal ischemia/reperfusion

Neurochemical Plasticity of nNOS-, VIP- and CART-Immunoreactive Neurons Following Prolonged Acetylsalicylic Acid Supplementation in the Porcine Jejunum

Aspirin, also known as acetylsalicylic acid (ASA), is a commonly used anti-inflammatory drug that has analgesic and antipyretic properties. The side effects are well known, however, knowledge concerning its influence on gastric and intestinal innervation is limited. The enteric nervous system (ENS) innervates the whole gastrointestinal tract (GIT) and is comprised of more than one hundred million neurons. The capacity of neurons to adapt to microenvironmental influences, termed as an enteric neuronal plasticity, is an essential adaptive response to various pathological stimuli. Therefore, the goal of the present study was to determine the influence of prolonged ASA supplementation on the immunolocalization of neuronal nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP) and cocaine- and amphetamine- regulated transcript peptide (CART) in the porcine jejunum. The experiment was performed on 8 Pietrain × Duroc immature gilts. Using routine double-labelling immunofluorescence, we revealed that the ENS nerve cells underwent adaptive changes in response to the induced inflammation, which was manifested by upregulated or downregulated expression of the studied neurotransmitters. Our results suggest the participation of nNOS, VIP and CART in the development of inflammation and may form the basis for further neuro-gastroenterological research.

Hyperglycaemia-Induced Downregulation in Expression of nNOS Intramural Neurons of the Small Intestine in the Pig

Diabetic autonomic peripheral neuropathy (PN) involves a broad spectrum of organs. One of them is the gastrointestinal (GI) tract. The molecular mechanisms underlying the pathogenesis of digestive complications are not yet fully understood. Digestion is controlled by the central nervous system (CNS) and the enteric nervous system (ENS) within the wall of the GI tract. Enteric neurons exert regulatory effects due to the many biologically active substances secreted and released by enteric nervous system (ENS) structures. These include nitric oxide (NO), produced by the neural nitric oxide synthase enzyme (nNOS). It is a very important inhibitory factor, necessary for smooth muscle relaxation. Moreover, it was noted that nitrergic innervation can undergo adaptive changes during pathological processes. Additionally, nitrergic neurons function may be regulated through the synthesis of other active neuropeptides. Therefore, in the present study, using the immunofluorescence technique, we first examined the influence of hyperglycemia on the NOS- containing neurons in the porcine small intestine and secondly the co-localization of nNOS with vasoactive intestinal polypeptide (VIP), galanin (GAL) and substance P (SP) in all plexuses studied. Following chronic hyperglycaemia, we observed a reduction in the number of the NOS-positive neurons in all intestinal segments studied, as well as an increased in investigated substances in nNOS positive neurons. This observation confirmed that diabetic hyperglycaemia can cause changes in the neurochemical characteristics of enteric neurons, which can lead to numerous disturbances in gastrointestinal tract functions. Moreover, can be the basis of an elaboration of these peptides analogues utilized as therapeutic agents in the treatment of GI complications.

Nitric oxide as an active substance in the enteric neurons of the porcine digestive tract in physiological conditions and under intoxication with bisphenol A (BPA)

Bisphenol A (BPA) is an organic substance, which is commonly used in the production of plastic. It is known that BPA has the negative impact on the living organism, affecting among others the reproductive organs, nervous, endocrine and immune systems. Nevertheless the knowledge about the influence of BPA on the enteric nervous system (ENS) is extremely scanty. On the other hand, nitric oxide is considered to be one of the most important neuronal factors in the ENS. The aim of the study was to investigate the influence of low and high doses of BPA on neuronal isoform nitric oxide synthase - like immunoreactive (nNOS-LI) nervous structures in the various parts of the porcine gastrointestinal (GI) tract using double immunofluorescence technique. The obtained results show that BPA affects nNOS-LI enteric neurons and nerve fibers, and the character and severity of observed changes depend on the fragment of the gastrointestinal tract, part of the ENS and dose of the toxin. It should be pointed out that even relatively low doses of BPA (0.05 mg/kg body weight/day) are not neutral for the organism and may change the number of nitrergic nervous structures in the stomach and intestine. Observed changes are probably connected with neurotoxic activity of BPA, but the exact mechanisms of them still remain unclear.

Protective effect of glutamine on the main and adjacent organs damaged by ischemia-reperfusion in rats

Intestinal ischemia and reperfusion (I/R) causes cellular and tissue damage to the intestine and remote organs such as the liver. Increased production of ROS and nitric oxide and dysregulation of cytoprotective enzymes may be involved in intestinal I/R. The aim was to evaluate the protective effects of glutamine on the intestine and liver of rats with intestinal I/R injury. Twenty male Wistar rats (300 g) were divided into four groups: sham-operated (SO), glutamine + SO (G + SO), I/R, and glutamine + I/R (G + I/R). Occlusion of the SMA for 30 min was followed by 15-min reperfusion. Glutamine (25 mg/kg/day) was administered once daily 24 and 48 h before I/R induction. Blood and tissue of were collected for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, histopathological analysis, immunohistochemistry of IL-1β and TNF-α, thiobarbituric acid reactive substance (TBARS) and nitric oxide, Nrf2/keap1, superoxide dismutase (SOD), NADPH quinone oxidoreductase1 (NQO1), inducible nitric oxide synthase (iNOS), heat shock protein (HSP70), glucose-regulated protein 78 (GRP78), and activating transcription factor 6 (ATF-6) by western blot. Statistic analysis by ANOVA-Student-Newman-Keuls test (mean ± SE) significantly was p < 0.05. Tissue damage, AST, ALT, IL-1β, TNF-α, TBARS, NO, Keap1, iNOS, GRP78, and ATF-6 expression were significantly lower in the G + I/R group as compared to the I/R group. Expression of Nrf2, SOD, NQO1, and HSP70, was significantly higher in the G + I/R group as compared to I/R group. Pre-treatment with glutamine provided protection against oxidative damage in the intestine and liver in an experimental model of intestinal I/R.

Acute infection with an avirulent strain of Toxoplasma gondii causes decreasing and atrophy of nitrergic myenteric neurons of rats

In the enteric nervous system (ENS), nitrergic neurons produce and use nitric oxide (NO) as an inhibitory motor neurotransmitter in response to parasitic infections, including those caused by Toxoplasma gondii. However, damage to the host caused by NO has been reported by various authors, and the role of NO in protection or cytotoxicity continues to be extensively studied. In this study, nitrergic neurons were investigated in the myenteric plexus of the jejunum and the distal colon of rats infected with 500 oocysts of the M7741 strain of T. gondii. Ten rats were randomly assigned into a control group (CG) and infected group (IG; received 500 sporulated oocysts of T. gondii orally). After 24h, the rats were euthanized, and samples of the jejunum and distal colon were obtained and processed for NADPH-diaphorase histochemical analysis. Quantitative and morphometric analysis of the nitrergic neurons in whole mounts containing the myenteric plexus was performed. There was a numeric reduction of nitrergic neurons per mm² in both jejunum and distal colon. The remaining nitrergic neurons suffered atrophy in the areas of the cell body and nucleus, which resulted in a decrease in cytoplasm. Thus, we conclude that an avirulent strain of T. gondii in a short time causes neuroplastic changes in the small and large intestine of rats.

Nitrergic neurons during early postnatal development of the prefrontal cortex in the rat: histochemical study

The presence of nitrergic cells in the prefrontal cortex has been confirmed, however little is known about the postnatal development of these cells. Nitrergic neurons were studied histochemically by using NADPH-diaphorase staining in the prefrontal cortex of male Wistar rats from postnatal day 7-21 (P7-21). Neuronal NADPH-diaphorase is a nitric oxide synthase that provides a specific histochemical marker for neurons producing nitric oxide (NO). NO acts as a neurotransmitter and intracellular signaling molecule in the nervous system. We observed in 7 day old rats NADPH-d containing neurons that were intensely stained. These neurons were bipolar with a short dendrite with average length of 23 μm. During the second postnatal week, the neurons were mainly bipolar and were rarely multipolar. By P14 the cells were located primarily in cortical layers III-VI. Nitrergic neurons of the 21 day old rats were histochemically identified as multipolar cells with long radial extending dendrites. Dendrites of neurons in 14 and 21 day old rats were a similar length with an average of 57 μm. These results suggest that nitrergic neurons differentiate during a relatively short period of time and reach their structural maturity by the end of the second week of postnatal development.

Histochemistry as an irreplaceable approach for investigating functional cytology and histology

In agreement with the evolution of histochemistry over the last fifty years and thanks to the impressive advancements in microscopy sciences, the application of cytochemical techniques to light and electron microscopy is more and more addressed to elucidate the functional characteristics of cells and tissue under different physiological, pathological or experimental conditions. Simultaneously, the mere description of composition and morphological features has become increasingly sporadic in the histochemical literature. Since basic research on cell functional organization is essential for understanding the mechanisms responsible for major biological processes such as differentiation or growth control in normal and tumor tissues, histochemical Journals will continue to play a pivotal role in the field of cell and tissue biology in all its structural and functional aspects.

On the future contents of a small journal of histochemistry

In the last three years, more than 70,000 scientific articles have been published in peer reviewed journals on the application of histochemistry in the biomedical field: most of them did not appear in strictly histochemical journals, but in others dealing with cell and molecular biology, medicine or biotechnology. This proves that histochemistry is still an active and innovative discipline with relevance in basic and applied biological research, but also demonstrates that especially the small histochemical journals should likely reconsider their scopes and strategies to preserve their authorship. A review of the last three years volumes of the European Journal of Histochemistry, taken as an example of a long-time established small journal, confirmed that the published articles were widely heterogeneous in their topics and experimental models, as in this journal's tradition. This strongly suggests that a journal of histochemistry should keep its role as a forum open to an audience as broad as possible, publishing papers on cell and tissue biology in a wide variety of models. This will improve knowledge of the basic mechanisms of development and differentiation, while helping to increase the number of potential authors since scientists who generally do not use histochemistry in their research will find hints for the applications of histochemical techniques to novel still unexplored subjects.

Effect of retinoic acid on the nitrergic innervation of meibomian glands in rats

The purpose of this study was to investigate the effect of prenatal administration of retinoic acid (RA) on the development of nicotinamide adenine dinucleotide diaphorase (NADPH-d) positive structures in the rat Meibomian glands. One mg/kg of RA was applied to pregnant Wistar rats intraperitonaelly during the gestational period in each of the 12th-14th embryonic days (totally 3 mg/kg). Sections of the central upper eyelids were investigated in rat pups on the 14th postnatal day. They were processed histochemically for NADPH-d, to study the presence and distribution of nitric oxide synthase (NOS) positive nerve structures. NADPH-d staining of Meibomian glands was compared in two groups of rat pups. In the control group, eyelids of 14 day-old rats were studied with no experimental intervention. The second group consisted of rat pups which were prenatally administered the excess of RA. Histochemical analysis of control eyelids revealed numerous NADPH-d well-stained acini of Meibomian glands arranged tightly into groups. Intensively stained vessels and NADPH-d/NOS-positive nerve fibers bordered acini of Meibomian glands. These structures were present in the submucosal layer as well. The analysis of RA group showed less numerous, shrunken acini of Meibomian glands that were seen not only smaller in size, but also in density of their staining and the amount of nitrergic nerve fibers around acini were considerably lowered. In the submucosa differences were noticed compared to the control group, there were numerous NADPH-d stained vessels accompanied by NADPH-d/NOS-positive nerve fibers. The excess of RA during the prenatal period may influence on the development and morphology of NADPH-d positive structures of rat's Meibomian glands.

Synthesis of PECAM-1-specific 64Cu PET imaging agent: evaluation of myocardial infarction caused by ischemia-reperfusion injury in mouse

A PECAM-1 specific PET imaging agent, PECAM-1-Ab-DOTA-(64)Cu, was synthesized by conjugating the anti-mouse PECAM-1 antibody with 2,2',2",2"'-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA) and subsequent labeling with (64)Cu. Positron Emission Tomography (PET) was successfully performed in a mouse model of myocardial infarction (MI) induced by an ischemia/reperfusion (I/R) injury, indicating the elevated expression of PECAM-1.

Identifying pathological biomarkers: histochemistry still ranks high in the omics era

In recent years, omic analyses have been proposed as possible approaches to diagnosis, in particular for tumours, as they should be able to provide quantitative tools to detect and measure abnormalities in gene and protein expression, through the evaluation of transcription and translation products in the abnormal vs normal tissues. Unfortunately, this approach proved to be much less powerful than expected, due to both intrinsic technical limits and the nature itself of the pathological tissues to be investigated, the heterogeneity deriving from polyclonality and tissue phenotype variability between patients being a major limiting factor in the search for unique omic biomarkers. Especially in the last few years, the application of refined techniques for investigating gene expression in situ has greatly increased the diagnostic/prognostic potential of histochemistry, while the progress in light microscopy technology and in the methods for imaging molecules in vivo have provided valuable tools for elucidating the molecular events and the basic mechanisms leading to a pathological condition. Histochemical techniques thus remain irreplaceable in pathologist's armamentarium, and it may be expected that even in the future histochemistry will keep a leading position among the methodological approaches for clinical pathology.