The present study evaluated the impact of neonatal administration of capsaicin (neurotoxin from red hot pepper used for sensory denervation) on postnatal development of the heart rate and ventricular contractility. In the rats subjected to capsaicin administration (100mg/kg) on postnatal days 2 and 3 and their vehicle-treated controls at the ages of 10 to 90
days, function of the sympathetic innervation of the developing heart
was characterized by evaluation of chronotropic responses to
metipranolol and atropine, norepinephrine concentrations in the heart, and norepinephrine release from the heart atria. Sensory denervation was verified by determination of calcitonin gene-related peptide levels in the heart. Direct cytotoxic effects of capsaicin were assessed on cultured neonatal cardiomyocytes. Capsaicin-treated rats displayed higher resting heart rates, lower atropine effect, but no difference in the effect of metipranolol. Norepinephrine tissue levels and release did not differ from controls. Contraction force of the right ventricular papillary
muscle was lower till the age of 60 days. Significantly reduced viability of neonatal cardiomyocytes was demonstrated at capsaicin concentration 100 μmol/l. Our study suggests that neonatal capsaicin treatment leads to impaired maturation of the developing cardiomyocytes. This effect cannot be attributed exclusively to sensory denervation of the rat heart since capsaicin acts also directly on the cardiac cells.
Propofol is a short-acting hypnotic agent used in human medicine for sedation and general anesthesia. Its administration can be associated with serious cardiovascular side-effects that include decrease in arterial blood pressure and cardiac output. The aim of the present study was to evaluate propofol effects on mitochondrial respiration, myocardial contractility and electrophysiology in the same samples isolated from the heart ventricles of adult rats. Mitochondrial oxygen consumption was
measured in permeabilized samples dissected from free walls of
both ventricles using high-resolution respirometry. State LEAK was determined with malate and glutamate. Active respiration was induced by ADP (state PI) and further by succinate, a Complex II substrate (PI+II). Rotenone was injected to measure state PII. Antimycin A, a Complex III inhibitor was used to determine residual oxygen consumption (ROX). N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride and ascorbate
were injected simultaneously for respirometric assay of cytochrome c oxidase activity (CIV). Isometric contractions and membrane potentials were determined on multicellular preparations isolated from right and left ventricles. Propofol concentrations used ranged from 0.005 to 0.5 mmol/l. All
respiratory parameters were significantly higher in the left control ventricles compared to the right ones. Propofol significantly decreased Complex I activity at concentration 0.025 mmol/l and papillary muscle contraction force at 0.1 mmol/l. Propofol did not affect action potential duration at any concentration studied. Our study suggests that mechanisms contributing to the impaired myocardial contraction during propofol anesthesia might include also mitochondrial dysfunction manifested by compromised
activity of the respiratory Complex I.
Huntingtonova choroba (HD) je dědičné neurodegenerativní onemocnění způsobené prodloužením úseku CAG repetic v důsledku zvýšeného počtu jejich opakování v prvním exonu genu pro huntingtin (Htt), které vede ke změně funkce proteinu. Nejvýraznějším neuropatologickým projevem onemocnění je ztráta striatálních neuronů. Přesné mechanismy zodpovědné za odumírání neuronů zatím nebyly uspokojivě objasněny. V poslední době přibývá počet vědeckých studií, které poukazují na to, že v tomto procesu hraje významnou roli poškození mitochondriálních funkcí a s tím související narušený energetický metabolismus. V této přehledné práci je poukázáno na nejvýraznější defekty mitochondrií způsobené vlivem mutované formy huntingtinu. Široké spektrum změn mitochondriálních funkcí zahrnuje oslabení biogeneze mitochondrií, Ca2+ homeostázy, nárůst oxidačního stresu, změny mitochondriální dynamiky a mnoho dalších procesů. Kombinace těchto aspektů zřejmě přispívá k odumírání striatálních neuronů u HD., Huntington ́s disease (HD) is an inherited neurodegenerative disease caused by an extended portion of CAG repeats induced higher number of repetitions in the first exon of the gene for huntingtin (Htt), which leads to changes in function of the protein. Most marked neuropathological manifestation of the disease is the loss of striatal neurons. The exact mechanisms responsible for neuronal death have not yet been sufficiently explained. In recent years increasing number of scientific studies that point out that this process plays important role in disruption of mitochondrial function and related impaired energy metabolism. This review is focused to the most striking mitochondrial defects caused by influence of mutated form of huntingtin. Broad spectrum of changes in mitochondrial function includes disruption of mitochondrial biogenesis, mitochondrial Ca2+ homeostasis, increased oxidative stress, changes in mitochondrial dynamics and many other processes. The combination of these aspects seems to contribute to the death of striatal neurons in HD., Marková M., Hansíková H., and Literatura
It is important to determine and clarify the variability of mammary carcinogenesis induction in animal experimental studies particularly in connection with chemoprevention projects. The circannual seasonal rhythms of hormone levels or various parameters within the immune system may involve factors participating in mammary gland carcinogenesis. In our study, 19 experiments were conducted and all of them lasted for about 25 weeks after chemical carcinogen administration (DMBA or NMU) under standard laboratory conditions. Females of two rat strains - a medium susceptible Sprague-Dawley strain and a very low susceptible Wistar:Han were used. We observed not only the effect of seasonal changes but also the effect of age after single or repeated carcinogen administration. The seasonal dependence of mammary carcinogenesis with higher tumor incidence during long days in comparison with winter short days has been demonstrated in Sprague-Dawley rats. In experiments on the Wistar:Han strain, certain features of seasonal character were recorded, although the very low susceptibility of this strain to mammary carcinogenesis might have influenced the results. A limited period of carcinogen administration in early puberty around postnatal days 43-46 (higher susceptibility), when compared to the period after postnatal day 50, is the factor significantly increasing incidence and frequency of mammary carcinogenesis in the Sprague-Dawley strain. Our results indicate the need to consider the effect of season and age of animals at the time of carcinogen administration on rat mammary carcinogenesis induction. However, the application of the results obtained in one strain of experimental animals may only lead to misleading conclusions., P. Kubatka, E. Ahlersová, I. Ahlers, B. Bojková, K. Kalická, E. Adámeková, M. Marková, M. Chamilová, M. Čermáková., and Obsahuje bibliografii