The growth of the prostate gland is androgen-dependent. Testosterone is converted to the most potent dihydrotestosterone (DHT) by 5α-reductase within the prostate. Androgen interacts with androgen receptors (AR) to regulate normal growth of the prostate and has also been implicated in both the progression of benign prostate hyperplasia and prostate cancer. This study was conducted to compare the mRNA expression of AR and 5α-reductase by the prostate gland from three age categories: immature, young-mature and old dogs. Quantitative gene expression was assessed by the real-time PCR and the results were expressed as a relative mRNA expression of the target gene. This study revealed that there was no significant difference in the mRNA expression of the AR gene by the prostate gland of immature, young and old dogs. In contrast, there is a highly significant (P<0.001) down-regulation in 5α-reductase gene by the prostate of young and old dogs as compared with immature dogs. However, there is no significant difference in mRNA expression of the 5α-reductase gene by the prostate gland from young and old dogs. This differential expression of AR and 5α-reductase genes, which are involved in the regulation of androgen effect on prostate gland, might reflect an age-dependent growth requirement of the gland for androgens., F. Shidaifat., and Obsahuje seznam literatury
a1_Fifty years ago, Lewis K. Dahl has presented a new model of salt hypertension – salt-sensitive and salt-resistant Dahl rats. Twenty years later, John P. Rapp has published the first and so far the only comprehensive review on this rat model covering numerous aspects of pathophysiology and genetics of salt hypertension. When we summarized 25 years of our own research on Dahl/Rapp rats, we have realized the need to outline principal abnormalities of this model, to show their interactions at different levels of the organism and to highlight the ontogenetic aspects of salt hypertension development. Our attention was focused on some cellular aspects (cell membrane function, ion transport, cell calcium handling), intra- and extrarenal factors affecting renal function and/or renal injury, local and systemic effects of reninangiotensin-aldosterone system, endothelial and smooth muscle changes responsible for abnormal vascular contraction or relaxation, altered balance between various vasoconstrictor and vasodilator systems in blood pressure maintenance as well as on the central nervous and peripheral mechanisms involved in the regulation of circulatory homeostasis. We also searched for the age-dependent impact of environmental and pharmacological interventions, which modify the development of high blood pressure and/or organ damage, if they influence the saltsensitive organism in particular critical periods of development (developmental windows). Thus, severe self-sustaining salt hypertension in young Dahl rats is characterized by pronounced dysbalance between augmented sympathetic hyperactivity and relative nitric oxide deficiency, attenuated baroreflex as well as by a major increase of residual blood pressure indicating profound remodeling of resistance vessels. Salt hypertension development in young but not in adult Dahl rats can be attenuated by preventive increase of potassium or calcium intake., a2_On the contrary, moderate salt hypertension in adult Dahl rats is attenuated by superoxide scavenging or endothelin-A receptor blockade which do not affect salt hypertension development in young animals., J. Zicha, ... [et al.]., and Obsahuje seznam literatury
The aim of the study was to investigate age-related changes in postural responses to platform translation with 3 various velocities. We focused on the influence of linear velocity using the smoothed profile of platform acceleration (till 100 cm.s−2 ). Eleven healthy young (20-31 years) and eleven healthy elderly (65-76 years) subjects were examined. The subjects stood on the force platform with their eyes closed. Each trial (lasting for 8 sec) with different velocity (10, 15, 20 cm.s−1 ) of 20 cm backward platform translation was repeated 4 times. We have recorded displacements of the centre of pressure (CoP) and the EMG activity of gastrocnemius muscle (GS) and tibialis anterior muscle (TA). The results showed increased maximal values of CoP responses to the platform translation. There was also observed a scaling delay of CoP responses to platform translation with different velocities in elderly. The EMG activity of GS muscle during backward platform translation was of about similar shape in both groups during the slowest platform velocity, but it increased depending on rising velocity. EMG activity of TA was not related to the platform velocity. Early parts of postural responses showed significant co-activation of TA and GS muscles of elderly. It is likely that elderly increased body stiffening in order to help their further balance control., Z. Halická ... [et al.]., and Obsahuje seznam literatury
Certain aspects of balance control change with age, resulting in a slight postural instability. We examined healthy subjects between 20-82 years of age during the quiet stance under static conditions: at stance on a firm surface and/or on a compliant surface with eyes either open or closed. Body sway was evaluated from centre of foot pressure (CoP) positions during a 50 sec interval. The seven CoP parameters were evaluated to assess quiet stance and were analyzed in three age groups: juniors, middle-aged and seniors. The regression analysis showed evident increase of body sway over 60 years of age. We found that CoP parameters were significantly different when comparing juniors and seniors in all static conditions. The most sensitive view on postural steadiness during quiet stance was provided by CoP amplitude and velocity in AP direction and root mean square (RMS) of statokinesigram. New physiological ranges of RMS parameter in each condition for each age group of healthy subjects were determined. Our results showed that CoP data from force platform in quiet stance may indicate small balance impairment due to age. The determined physiological ranges of RMS will be useful for better distinguishing between small postural instability due to aging in contrast to pathological processes in the human postural control., D. Abrahamová, F. Hlavačka., and Obsahuje bibliografii a bibliografické odkazy
Vascular aging is associated with both structural and functional changes that can take place at the level of the endothelium, vascular smooth muscle cells and the extracellular matrix of blood vessels. With regard to the endothelium, reduced vasodilatation in response to agonists occurs in large conduit arteries as well as in resistance arteries with aging. Reviews concerning the different hypotheses that may account for this endothelial dysfunction have pointed out alterations in the equilibrium between endothelium-derived relaxing and constricting factors. Thus, a decreased vasorelaxation due to nitric oxide and, in some arteries, endothelium-derived hyperpolarizing factor as well as an increased vasoconstriction mediated by cyclooxygenase products such as thromboxane A2 are likely to occur in age-induced impairment of endothelial vasodilatation. Furthermore, enhanced oxidative stress plays a critical role in the deleterious effect of aging on the endothelium by means of nitric oxide breakdown due to reactive oxygen species. The relative contribution of the above phenomenon in age-related endothelial dysfunction is highly dependent on the species and type of vascular bed., R. L. Matz, C. Schott, J. C. Stoclet, R. Andriantsitohaina., and Obsahuje bibliografii
Hypertension-induced myocardial metabolic, structural and electrophysiological remodeling deteriorates with aging and contributes to both heart failure and occurrence of malignant arrhythmias. It has been shown in clinical trials that n-3 polyunsaturated fatty acids (n-3 PUFA) reduce the incidence of cardiovascular diseases and sudden cardiac death. We investigated the cardioprotective effects of n-3 PUFA in aged spontaneously hypertensive rats (SHR) and possible cellular mechanisms involved. Male and female 14-month-old SHR were fed with n-3 PUFA (Vesteralens, Norway, 20 mg/day for two months) and compared with untreated SHR. Results showed that n-3 PUFA supplementation led to 1) significant decline of blood pressure; 2) suppression of inducible ventricular fibrillation (VF) by 57 % (male) and 67 % (female) , although the arrhythmogenic substrates, like fibrosis, hypertrophy and abnormal gap junctions distribution were not eliminated; 3) preservation of the cardiomyocytes and the inte grity of their junctions; 4) enhancement of energetic metabolism enzyme activity; 5) augmentation of capillary density associated with increased alkaline phosphatase and decreased dipeptidyl peptidase-4 (DPP4) activity and 6/ increase in gap junction channel connexin-43 expression. Thus, aged male as well as female SHR benefit from n-3 PUFA supplementation that results in decrease in VF susceptibility, partly due to an improvement of myocardial metabolic state, cardiomyocyte and cell-to-cell junctions integrity and Cx43 up-regulation., M. Mitašíková, S. Šmidová, A. Mascaliová, V. Knezl, K. Dlugošová, Ľ. Okruhlicová, P. Weismann, N. Tribulová., and Obsahuje bibliografii a bibliografické odkazy
Nitrogen-containing bisphosphonates were found to inhibit farnesyl diphosphate synthase - an essential enzyme in the cholesterol biosynthesis pathway, but their effect on cholesterol synthesis per se in the central nervous system (CNS) remains unknown. The aim of the present study was to examine possible influence of a representative agent alendronate on cholesterol synthesis rates in selected parts of rat CNS and on plasma cholesterol level. Two groups of rats were orally administered either alendronate (3 mg/kg b.w. ) or vehicle for 9 days. At the end of experiment, brain (basal ganglia, frontal cortex and hippocampus) and spinal cord were isolated and cholesterol synthesis was determined using the technique of deuterium incorporation from deuterated wa ter. In the alendronate group significant reductions of choleste rol synthesis rates were detected in frontal cortex, hippocampus and spinal cord (p<0.001). However, the experimental treatment did not produce a significant alteration in the levels of plasma cholesterol. In conclusion, this study brings the first experimental evidence of the inhibition of cholesterol biosynthesis with alendronate in central nervous system., Ľ. Cibičková, R. Hyšpler, N. Cibiček, E. Čermáková, V. Palička., and Obsahuje bibliografii
The consequences of epileptic seizures related to postictal inhibition in early postictal period include postictal analgesia. We studied this phenomenon over 96 h following flurothyl-induced seizures in adult male Wistar rats. Nociception of control (no seizure) and seizured groups were tested using the plantar and von Frey hair tests. We determined latency of forepaw and hind paw reactions using plantar tests and the number of von Frey hairs reactions. Shortly after seizures, longer plantar test latencies were seen relative to the control group. Before the seizures the plantar test reaction times were significantly shorter in forepaws than in hind paws. The effect disappeared post-seizure and surprisingly, it also disappeared at the corresponding time in controls; it reappeared after 48 h in the seizure group and after 24 h in controls. Differences in the von Frey hairs test occurred at 5 and 60 min post-seizure, however, these differences could not be explained by limb anatomy; although, different thermal and mechanical nociception mechanisms could be significant. The unexpected reactions in controls could be related to brief social and physical interactions between the two groups. and J. Mareš, R. Rokyta.
In the present work neonatal male and female Wistar rats were treated intraperitoneally with monosodium glutamate (MSG 2 mg/kg b.w.) or saline (controls) daily for 4 day after birth. At the age of 30 and 80 days, the alkaline phosphatase activity (AP) in the brush border of individual enterocytes, the body fat content and Lee´s index of obesity were analyzed. Microdensitometrical quantification of AP was significantly increased on day 30 in males (P<0.01) and on day 80 in MSG-treated male and female rats (P<0.001) as compared to the controls. MSG administration also increased the body fat weight and the obesity index significantly (P<0.001) in 80-day-old animals, but was without any significant effect on their food intake. Our results showed that a) neonatal MSG-treatment may significantly change the intestinal function and b) the investigation of the intestinal enzyme activities may be important in further studies on MSG-induced and other forms of obesity., Š. Mozeš, Ľ. Lenhardt, A. Martinková., and Obsahuje bibliografii
The polymorphisms of the tumor suppressor gene p53 in exon 4 (p53 BstUI) and in intron 6 (p53 MspI) have been suggested to be associated with the genetically determined susceptibility in diverse types of human cancer. In our hospital-based case-control study, we examined the allele and genotype incidence of these polymorphisms as well as their haplotype combinations in 60 brain tumor patients (27 males and 33 females) and 183 controls without malignancies. The genotype characteristics were determined by the PCR-based RFLP method using DNA extracted from peripheral blood. In this study we show that the p53 BstUI and the p53 MspI polymorphisms are not associated with increased risk of brain tumors. Thus, we conclude that the p53 BstUI and the p53 MspI polymorphic sites within the tumor suppressor gene p53 do not represent genetic determinants of susceptibility to brain tumors., E. Biroš, I. Kalina, A. Kohút, E. Bogyiová, J. Šalagovič, I. Šulla., and Obsahuje bibliografii