Michał Majewski

The Influence of Resiniferatoxin (RTX) and Tetrodotoxin (TTX) on the Distribution, Relative Frequency, and Chemical Coding of Noradrenergic and Cholinergic Nerve Fibers Supplying the Porcine Urinary Bladder Wall

The present study investigated the influence of intravesically instilled resiniferatoxin (RTX) or tetrodotoxin (TTX) on the distribution, number, and chemical coding of noradrenergic and cholinergic nerve fibers (NF) supplying the urinary bladder in female pigs. Samples from the bladder wall were processed for double-labelling immunofluorescence with antibodies against cholinergic and noradrenergic markers and some other neurotransmitter substances. Both RTX and TTX caused a significant decrease in the number of cholinergic NF in the urinary bladder wall (in the muscle coat, submucosa, and beneath the urothelium). RTX instillation resulted in a decrease in the number of noradrenergic NF in the submucosa and urothelium, while TTX treatment caused a significant increase in the number of these axons in all the layers. The most remarkable changes in the chemical coding of the NF comprised a distinct decrease in the number of the cholinergic NF immunoreactive to CGRP (calcitonin gene-related peptide), nNOS (neuronal nitric oxide synthase), SOM (somatostatin) or VIP (vasoactive intestinal polypeptide), and an increase in the number of noradrenergic NF immunopositive to GAL (galanin) or nNOS, both after RTX or TTX instillation. The present study is the first to suggest that both RTX and TTX can modify the number of noradrenergic and cholinergic NF supplying the porcine urinary bladder.

The toxic effects of monosodium glutamate (MSG) – The involvement of nitric oxide, prostanoids and potassium channels in the reactivity of thoracic arteries in MSG-obese rats

ABSTRACT We investigated the potential effects of monosodium glutamate (MSG)‐induced obesity with regards to nitric oxide and prostanoid production, as well as potassium channel function, in rat thoracic arteries. Newborn male Wistar rats were injected intraperitoneally with typically reported MSG (4.0mg/g) once daily for 4 consecutive days. At 90days postnatal, the rats were sacrificed and the thoracic aortas were evaluated for vascular responses and for prostanoid production. Nitric oxide was studied with calcium ionophore (A23187), acetylcholine (ACh) and sodium nitroprusside (SNP). The release of prostanoids was measured under basal and ACh‐stimulated conditions, and the vasomotor effect of exogenous thromboxane A2 mimetic, U46619 was assessed. Potassium channel activities were analyzed using an NS1619 opener for BKCa channels and pinacidil for KATP channels. Arteries from MSG‐obese rats exhibited a reduced maximal contraction to potassium chloride and hyper‐responsiveness to U46619, suggesting that MSG also alters the responsiveness of vascular smooth muscles. The endothelium‐dependent relaxation to ACh and A23817 was attenuated, suggesting low nitric oxide bioavailability. The hypersensitivity of arteries to an exogenous nitric oxide donor, SNP, occurred. The secondary contraction to A23817 was augmented, suggesting increased activation of the prostanoid receptor. The prostanoid release was increased in both basal‐ and acetylcholine‐stimulated rings. In addition, down‐regulation of KATP and BKCa channels influenced hyperpolarizing mechanisms. Our findings suggest that increased prostanoid production and hypersensitivity to thromboxane A2 together with down‐regulation of potassium channels and low nitric oxide bioavailability may contribute to the increase in blood pressure found in adult MSG‐obese male rats.

Toxicity and cardiac effects of acute exposure to tryptophan metabolites on the kynurenine pathway in early developing zebrafish (Danio rerio) embryos

&NA; Defects in tryptophan metabolism on the l‐kynurenine pathway (KP) are implicated in a number of human diseases, including chronic kidney disease, brain edema or injury, tuberculosis and malaria – as well as cancer, neurodegenerative and autoimmune disorders. However, it is unclear to what extent detrimental effects of exposure to tryptophan metabolites might impact the early development of organism. Thus, this study examined the effects of KP exposure in zebrafish embryos starting at the blastula period (4 hpf) and the segmentation stage (24 hpf). 24‐hour EC50 and LC50 values were determined in 4 hpf embryos as: 26.74 and 331.6 &mgr;M for anthranilic acid (AA), 62.88 and 616.4 &mgr;M for quinolinic acid (QUIN), and EC50 – 96.10 &mgr;M for picolinic acid (PA) and LC50 – 400 &mgr;M in kynurenic acid (KYNA). In addition, treatment with nanomolar concentrations of KYNA (50 nM, 48 and 72 hpf embryos) caused a dose‐dependent increase in heartbeat. The increase was also seen with l‐kyn treatment (50 &mgr;M, 72 hpf), which was the opposite of other applied l‐kyn metabolites. A significant drop in heartbeat was observed after a 20‐min acute exposure to 626 &mgr;M PA, 594 &mgr;M XA and 499 &mgr;M QUIN, and complete recovery was seen only when PA had been removed. Concentrations of KP metabolites reached in people with different pathological conditions did not exert toxicity to zebrafish embryos and seems to be safe for developing embryos and therefore, the risk of developing impairments in pregnancy of women carrying KP‐associated pathologies is initially low. Highlights24‐hour EC50 values were: AA ‐ 26.7 &mgr;M, QUIN ‐ 62.9 &mgr;M and PA ‐ 96.1 &mgr;M.AA, KYNA and QUIN are potent metabolites with 24‐hour LC50 331.6, 400 and 616.4 &mgr;M.KYNA (50 nM) and l‐kyn (50 &mgr;M) caused a dose‐dependent increase in heartbeat.KP related pathologies appear to be safe for developing organisms.

Effect of dietary copper nanoparticles versus one copper (II) salt: Analysis of vasoreactivity in a rat model

BACKGROUNDnVascular defects in the mechanical properties of aorta and muscular arteries have been previously reported in animals with copper-deficient feed. However, the interaction between copper nanoparticles (CuNPs) and mechanical properties of arteries has not been reported. Hence, the present study was aimed to evaluate the effect of copper nanoparticles on the vasoreactivity of rat isolated thoracic arteries.nnnMETHODSnIn this study, 5 week old male Wistar rats were fed a copper-adequate diet (CuA, 6.5mg copper/kg diet), copper-deficient diet (CuD) and copper-modified diets, enriched with copper as a salt (CuS) and as copper nanoparticles (CuNPs) of 40-60nm in diameter.nnnRESULTSnThere was a strong relationship between CuNPs and CuS administration in the tensile strength of the thoracic aorta subjected to phenylephrine treatment in the concentration range of 10-7-10-5M. This was also seen between CuNPs and the control diet in the same concentration ranges. In addition vasodilation induced by acetylcholine at the concentration range of 10-7-10-5M was significantly reduced in CuD and NPs feed animals. In CuNPs fed rats, activities of Cu,Zn-SOD, CAT and copper concentration in cardiomyocytes were not influenced when compared with CuS control. In contrast, in CuS-low diet the activities of studied enzymes and copper concentration were pointing towards copper deficiency.nnnCONCLUSIONSnOur results demonstrate for the first time that the observed effects of copper administration in the form of NPs are attributed mainly to the NPs rather than copper itself. Thus another mechanism not related with Cu,Zn-SOD and CAT seems to be involved.

Assessment of a threat of hypomagnesemia in patients with cancer, based on patients' medication record and dietary questionnaire

Magnesium deficiency among oncological patients is a complex condition. Hypomagnesaemia is observed during anti-cancer chemotherapy and during treatment of certain co-existing disorders. Assessing the magnesium status is difficult, as serum levels have little correlation with the total body magnesium status. Thus, the aim of this study was to provide more recent data about possible causes of magnesium insufficiency among oncological patients with the focus on the health status, pharmacological treatment and intake of magnesium-rich food products. 380 oncological patients (304 reliable surveys) with concurrent chemotherapy, radiotherapy and surgery from the Clinical Department of Oncological Surgery, MSW Hospital, Olsztyn, Poland were reviewed retrospectively between January 2013 and April 2016. The mean magnesium dietary intake was 224 mg daily among women and 295 mg per day among men, which was found insufficient. Consumption of some food products rich in magnesium such as cacao, legumes, nuts and seeds was found to be scarce. Dietary supplementation of magnesium was also inadequate (3%). In addition, high daily consumption of coffee (67.1%) and strong tea (81.85%) was reported. Moreover, obesity (47.8%) together with gastrointestinal disorders such as diarrhoea and vomiting (52%) persisted, which may have further contributed to magnesium deficiency. Patient medication record has also revealed previous intake of some drugs that are implicated in the development of hypomagnesemia. Regular monitoring for enteritis and hypomagnesemia with timely intervention as well as inclusion of magnesium-rich food products in daily diet could help improve compliance, decrease the incidence of treatment interruptions and thereby help achieve the optimum treatment outcome.