Tachykinin-related peptides (TRPs) are one of the most prominent families of neuropeptides in the animal kingdom. Insect TRPs display strong structural and functional homology to vertebrate ...tachykinins (TKs). To study functional homologies between these two neuropeptide families, the influence of human substance P (SP, one of the essential vertebrate TKs) on the immune system of the mealworm beetle, Tenebrio molitor L., was analysed.
Human SP influences the phagocytic abilities of T. molitor haemocytes. Peptide injection leads to an increase in the number of haemocytes participating in the phagocytosis of latex beads. In contrast, incubation of haemocytes from non-injected beetles in a solution of physiological saline and SP causes a decrease in phagocytic activity. Treatment with human SP also led to increased adhesion of haemocytes, but no changes in the arrangement of the F-actin cytoskeleton were observed. Interestingly, 6 h after human SP injection, increased DNA integrity in T. molitor haemocytes was reported. The opposite effects were observed 24 h after SP injection.
Human SP caused the upregulation of humoral immune responses, such as phenoloxidase (PO) activity in the T. molitor haemolymph, and the downregulation of immune-related genes encoding coleoptericin A, tenecin 3 and Toll receptor. However, genes encoding attacin 2 and cecropin were upregulated. Despite these differences, the antimicrobial activity of T. molitor haemolymph was significantly lower in beetles injected with SP than in control beetles. Moreover, an analysis of the direct influence of SP on lysozyme activity was performed. Our results suggest that SP at a concentration of 10−6 M can directly inhibit lysozyme activity. However, an opposite effect was reported after the application of SP at a concentration of 10−4 M.
The presented results suggest structural and functional homology between TK signalling in vertebrates and insects. Primarily, this was visible in the context of the humoral response and general antimicrobial activity of T. molitor haemolymph. However, some of the results related to haemocyte function may also indicate the importance of the TK and TRP sequences for evoking immunological effects.
•Human substance P influence insect cellular and humoral response.•Human substance P can directly affect lysozyme activity.•Results suggest homology between TK signalling in vertebrates and insects.
Tachykinin-related peptides (TRPs) are important neuropeptides. Here we show that they affect the insect immune system, especially the cellular response. We also identify and predict the sequence and ...structure of the tachykinin-related peptide receptor (TRPR) and confirm the presence of expression of gene encoding TRPR on Tenebrio molitor haemocytes.
After application of the Tenmo-TRP-7 in T. molitor the number of circulating haemocytes increased and the number of haemocytes participating in phagocytosis of latex beads decreased in a dose- and time-dependent fashion. Also, Tenmo-TRP-7 affects the adhesion ability of haemocytes. Six hours after injection of Tenmo-TRP-7, a decrease of haemocyte surface area was observed under both tested Tenmo-TRP-7 concentrations (10−7 and 10−5 M). The opposite effect was reported 24 h after injection, which indicates that the influence of Tenmo-TRP-7 on modulation of haemocyte behaviour differs at different stages of stress response. Tenmo-TRP-7 application also resulted in increased phenoloxidase activity 6 and 24 h after injection.
The assessment of DNA integrity of haemocytes showed that the injection of Tenmo-TRP-7 at 10−7 M led to a decrease in DNA damage compared to control individuals. This effect was only visible 6 h after Tenmo-TRP-7 application. After 24 h, Tenmo-TRP-7 injection increased DNA damage.
We also confirmed the expression of immune-related genes in nervous tissue of T. molitor. Transcripts for genes encoding receptors participating in pathogen recognition processes and antimicrobial peptides were detected in T. molitor brain, retrocerebral complex and ventral nerve cord. These results may indicate a role of the insect nervous system in pathogen recognition and modulation of immune response similar to vertebrates.
Taken together, our results support the notion that tachykinin-related peptides probably play an important role in the regulation of the insect immune system. Moreover, some resemblances with action of tachykinin-related peptides and substance P showed that insects can be potential model organisms for analysis of hormonal regulation of conserved innate immune mechanisms.
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•Insect tachykinin-related peptides possess immunomodulatory properties.•Tachykinin-related peptides influence haemocytes activity.•Tachykinin-related peptides application increase activity of phenoloxidase.•Tachykinin-related peptides can reduce DNA damages in haemocytes.•Immune-related genes are present in the Tenebrio nervous system.
Red blood cells (RBCs) are the most abundant cells in the human blood that have been extensively studied under morphology, ultrastructure, biochemical and molecular functions. Therefore, RBCs are ...excellent cell models in the study of biologically active compounds like drugs and toxins on the structure and function of the cell membrane. The aim of the present study was to explore erythrocyte ghost's proteome to identify changes occurring under the influence of three bee venom peptides-melittin, tertiapin, and apamin. We conducted preliminary experiments on the erythrocyte ghosts incubated with these peptides at their non-hemolytic concentrations. Such preparations were analyzed using liquid chromatography coupled with tandem mass spectrometry. It was found that when higher concentrations of melittin and apamin were used, fewer proteins were identified. Moreover, the results clearly indicated that apamin demonstrates the greatest influence on the RBCs ghosts proteome. Interestingly, the data also suggest that tertiapin exerted a stabilizing effect on the erythrocyte membrane. The experiments carried out show the great potential of proteomic research in the projects focused on the toxin's properties as membrane active agents. However, to determine the specificity of the effect of selected bee venom peptides on the erythrocyte ghosts, further proteomic research should be focused on the quantitative analysis.
Chronic exposure to cigarette smoke causes an imbalance in the ratio of PGI2 and TXA2 production and is believed to favor the development of atherosclerosis. Components of the particulate phase of ...smoke (especially nicotine) as well as the gas phase of smoke have been shown to adversely alter arachidonic acid metabolism. To determine the relative participation of nicotine, particulate and gas phases in eliciting an imbalance in TXA2 formation, male Sprague-Dawley rats were chronically exposed (7 days/wk/mo.) to freshly generated whole smoke or gas phase from University of Kentucky Reference cigarettes and allowed access to regular drinking water or to water supplemented with nicotine (10 micrograms/ml). COHb levels were monitored to confirm smoke or gas phase inhalation. All treatment groups had lower body weights than shams. No differences in body weights were observed between smoke (+/- oral nicotine) and gas phase (+/- oral nicotine) treatment groups but all were significantly lower than oral nicotine treated animals. Platelet TXA2 production was elevated in all treatment groups compared to shams. No differences in TXA2 production were observed between smoke (+/- oral nicotine), gas phase and oral nicotine treated animals. Animals receiving gas phase/oral nicotine exhibited significantly higher platelet TXA2 production compared to the other treatments. Constituents of the gas phase as well as the particulate phase of whole smoke were both shown to elevate platelet TXA2 formation. Components of the particulate matter appear to modulate the effects of nicotine and the gas phase in the perturbation of TXA2 production in the rat smoking model.
Aqueous suspensions of aspirin or acetaminophen (125 and 250 mg/kg/day) were administered orally to pregnant Sprague-Dawley rats on Days 8-19 of gestation Day 20, each rat was sacrificed and the ...uterus was examined in situ. Each fetal-placental unit was resected and examined. Fetuses from rats given 125 or 250 mg/kg/day of aspirin were shorter and weighed less than those obtained from control rats. In animals receiving the higher dose of aspirin, the placentas were smaller and the number of fetal resorptions was increased. Acetaminophen (250 mg/kg/day) did not affect fetal length or weight or the incidence of resorption. Acetaminophen interfered less with the normal growth of the rat fetus and placenta than did aspirin.
Adriamycin treatment in vivo or addition to incubation mixtures in vitro inhibits hepatic drug metabolism. It has been suggested that adriamycin-induced membrane lipid peroxidation may be a mechanism ...responsible for this activity in vitro. To determine if similar mechanisms operate in vivo, adriamycin inhibition of drug metabolism was compared in rats whose tissue lipid peroxidizability was altered by manipulating dietary levels of vitamin E. Weanling rats maintained on vitamin E deficient (0 ppm) or supplemented (10 or 100 ppm) diets for 12 weeks were given either adriamycin, 5 mg/kg/week, or equal volumes of the saline vehicle for 3 weeks intraperitoneally. Vitamin E deficiency alone (0 ppm, saline pretreatment) produced a 37% increase in hepatic lipid peroxidation without any appreciable alteration in hepatic aniline hydroxylase, ethylmorphine N-demethylase or aryl hydrocarbon hydroxylase activities. Adriamycin pretreatment altered hepatic lipid peroxidizability over corresponding saline pretreated controls dependent on dietary vitamin E. No increase was seen in the 100 ppm group, while 44% and 500% increases occurred at 10 and 0 ppm vitamin E, respectively. Adriamycin pretreatment decreased drug-metabolizing enzyme activity by an average of 32% for aniline hydroxylase, 26% for ethylmorphine N-demethylase and 63% for aryl hydrocarbon hydroxylase. Statistically, decreases in drug metabolism were independent of dietary vitamin E and did not correlate with lipid peroxidizability. These data would suggest that in vivo adriamycin-induced depression of hepatic drug-metabolizing enzymes is not mediated by elevated lipid peroxidation.
In order to investigate the possibility of pulmonary first-pass metabolism of nicotine inhaled in tobacco smoke, the absorption and disposition of 14C-nicotine were studied in an isolated perfused ...rabbit lung preparation after nicotine administration directly into the perfusing blood and tobacco smoke administration via in the inspired tracheal air. After administration into the perfusing medium, the rate of nicotine metabolism was first-order and dose-independent at the two doses studies (0.1 and 1.0 mg) but lung metabolic clearance was quite low (3 ml/min) relative to whole body clearance (140 ml/min) measured by administering 14C-nicotine to intact rabbits. Accumulation of nicotine by lung was not extensive (13-23% of the dose administered). After administration of tobacco smoke from 14C-nicotine-spiked cigarettes, absorption of nicotine was rapid but the rate of metabolism was markedly reduced compared to the studies in which drug was administered in the perfusing medium. This reduction in the rate of metabolism was apparently caused by some component of tobacco smoke but was shown to be unrelated to the level of carbon monoxide in the perfusate. The slow clearance of nicotine by rabbit lung (which is further reduced after smoke administration) compared to a high pulmonary blood flow rate makes unlikely the possibility of significant first-pass lung metabolism in smokers.
The uptake and metabolism of isosorbide dinitrate was investigated in the recirculating isolated perfused rabbit lung and in lung homogenate 9000 X g supernatant. Concentration versus time profiles ...from the isolated lung experiments indicate rapid metabolism of isosorbide dinitrate and corresponding increases in the metabolites 5-isosorbide mononitrate, 2-isosorbide mononitrate, and isosorbide. The data suggest that the mononitrates formed in the lung tissue were converted to isosorbide at an extraordinarily high rate. Surprisingly, the rate of appearance of completely denitrated isosorbide was greater when isosorbide dinitrate was administered to the lung than when the mononitrate metabolites of isosorbide dinitrate were administered. The results suggest rapid metabolism of a substantial portion of the mononitrates formed endogenously from isosorbide dinitrate before partitioning of mononitrates into the perfusion medium could occur. The metabolism of isosorbide dinitrate in lung homogenate 9000 X g supernatant exhibited a metabolic scheme kinetically different from the intact lung studies, as isosorbide was formed slowly from a mononitrate intermediate and not by a near-simultaneous cleavage of both nitrate ester groups. Intravascular multiple-dose studies did not demonstrate any inhibition between isosorbide dinitrate and the mononitrates.
Chronic exposure to cigarette smoke causes an imbalance in both PGI2 and TXA2 production which is believed to favor the development of atherosclerosis. Nicotine, a major constituent of smoke, has ...been shown to adversely alter arachidonic acid metabolism. To determine whether varying doses of nicotine in cigarettes would influence the extent of PGI2/TXA2 alterations, male Sprague-Dawley rats were chronically exposed (7 days/wk/6 mo.) to smoke from University of Kentucky Reference cigarettes containing "low" nicotine (3A1), "high" nicotine (2R1) and "low" nicotine cigarettes spiked with enough nicotine to deliver amounts equivalent to the 2R1. COHb levels were monitored to confirm smoke inhalation. No differences in body weights were observed between treatment groups, but all were significantly lower than sham. Aortic PGI2 formation was not significantly depressed by any of the treatment groups compared to shams. Platelet TXA2 production was elevated in all treatment groups compared to shams, irrespective of nicotine content. In the rat smoking model, low nicotine cigarettes do not appear to be an advantage over higher nicotine cigarettes.
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