There has been increasing evidence in recent years for the hypothesis of bones as endocrine organs. Osteocalcin, long considered just a marker of new bone formation, is now seen as the first hormone produced by bones, and seems to be associated with regulating glucose metabolism and reproduction. The aim of this work was to monitor changes of osteocalcin in reaction to hypoglycemia, and determine if there are differences in such reactions between the sexes. The study included 61 healthy probands with physiological calciophosphate metabolism (30 men and 31 women). We applied to each of them an insulin tolerance test, and then monitored levels of undercarboxylated osteocalcin and reactions to hypoglycemia at regular time intervals. We found differences in the reaction to hypoglycemia between the sexes. In men there was a significant decline in undercarboxylated osteocalcin between the 30 and 40 min (p<0.0015), which reflects a reaction to a glycemic decline between 25-30 min, followed by reversal. Low undercarboxylated osteocalcin in men lasted up to 90 min, after which they returned to levels before the test. In women we did not find any significant changes in undercarboxylated osteocalcin levels. Changes in undercarboxylated osteocalcin induced by hypoglycemia indicate a relationship between bones and glucose metabolism. There was an interesting difference between the sexes. However, a definitive conclusion about the role of osteocalcin in human metabolism will require numerous future studies., Michaela Dušková, Lucie Kolátorová, Hana Jandíková, Hana Pospíšilová, Luboslav Stárka., and Obsahuje bibliografii
Neuroimaging methods have been used to study differences of brain function between males and females. Differences in working memory have been also investigated, but results of such studies are mixed with respect to behavioral data, reaction times and activated brain areas. We tried to analyze functional MRI data acquired during the working memory task and search for differences of brain activation between genders. 20 healthy righthanded volunteers (10 males and 10 females) participated in the study. All of them were university students or fresh graduates. Subjects underwent block designed verbal working memory task (Item Recognition Task) inside the MRI scanner. Standard singlesubject pre-processing and group fMRI analyses were performed using the FEAT software from FSL library. In the behavioral data, there was no statistically significant difference in the number of correct responses during the task. The task activated similar bilateral regions of frontal, parietal, temporal and occipital lobes, basal ganglia, the brainstem and in the cerebellum, which corresponds to the previous verbal working memory neuroimaging research. In direct comparison, there was no statistically significant difference in brain activation between small samples of male and female young healthy volunteers., Z. Tüdös, P. Hok, P. Hluštík, A. Grambal., and Obsahuje bibliografii
For better understanding of pathophysiological processes leading to increased retention of sodium as a consequence of hyperlipidemia, the properties of renal Na,K-ATPase, a key enzyme involved in maintaining sodium homeostasis in the organism, were studied. Enzyme kinetics of renal Na,K-ATPase were used for characterization of ATP- and Na+-binding sites after administration of fish oil (FO) (30 mg · day-1) or atorvastatin (0.5 mg·100 g-1 day-1) to healthy Wistar rats and rats with hereditary hypertriglyceridemia of both genders. Untreated healthy Wistar and also hypertriglyceridemic female rats revealed higher Na,K-ATPase activity as compared to respective untreated male groups. Hypertriglyceridemia itself was accompanied with higher Na,K-ATPase activity in both genders. Fish oil improved the enzyme affinity to ATP and Na+, as indicated by lowered values of K m and K Na in Wistar female rats. In Wistar male rats FO deteriorated the enzyme in the vicinity of the Na+-binding site as revealed from the increased K Na value. In hypertriglyceridemic rats FO induced a significant effect only in females in the vicinity of the sodium binding sites resulting in improved affinity as documented by the lower value of KNa. Atorvastatin aggravated the properties of Na,K-ATPase in both genders of Wistar rats. In hypertriglyceridemic rats protection of Na,K-ATPase was observed, but this effect was bound to females only. Both treatments protected renal Na,K-ATPase in a gender specific mode, resulting probably in improved extrusion of excessive intracellular sodium out of the cell affecting thus the retention of sodium in hHTG females only., N. Vrbjar ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
During the early postnatal age environmental signals underlie the development of sensory systems. The visual system is considered as an appropriate system to evaluate role of sensory experience in postnatal development of sensory systems. This study was made to assess the effect of visual deprivation on strategy of arm selection in navigation of radial arm maze. Six-week-old light- (LR, control) and dark-reared (DR) rats were trained for correct choices and adjacent arms tasks. Our results showed that both the LR and DR animals equally selected correct arms. In the adjacent arms task, however, the control group significantly outperformed the DR animals. While the LR males and females displayed some differences in performing the tasks, no sex dependency was found in the performance of the DR group. These findings indicate that the lack of visual experience is likely to influence the strategy selection as well as sex differences. Thus the difference in the performance of LR and DR animals seems to be due to the male rather than female behavior., M. Salami., and Obsahuje bibliografii a bibliografické odkazy
Acute liver failure (ALF) is a clinical syndrome with high mortality rate, resulting from widespread hepatocyte damage. Its pathophysiological background is still poorly understood and preclinical studies evaluating pathophysiology and new potential therapeutic measures are needed. The model of ALF induced by administration of thioacetamide (TAA) in Lewis rats is recommended as optimal; however, the limitation of previous studies was that they were performed predominantly in male rats. In view of the growing recognition that sex as a biological variable should be taken into consideration in preclinical research, we examined its role in the development of TAA-induced ALF in Lewis rats. We found that, first, intact male Lewis rats showed lower survival rate than their female counterparts, due to augmented liver injury documented by higher plasma ammonia, and bilirubin levels and alanine aminotransferase activity. Second, in female rats castration did not alter the course of TAA-induced ALF whereas in the male gonadectomy improved the survival rate and attenuated liver injury, reducing it to levels observed in their female counterparts. In conclusion, we found that Lewis rats show a remarkable sexual dimorphism with respect to TAA-induced ALF, and male rats display dramatically poorer prognosis as compared with the females. We showed that testosterone is responsible for the deterioration of the course of TAA-induced ALF in male rats. In most general terms, our findings indicate that in the preclinical studies of the pathophysiology and treatment of ALF (at least of the TAA-induced form) the sex-linked differences should be seriously considered., Eva Koblihová, Iveta Mrázová, Zdenka Vaňourková, Hana Maxová, Miroslav Ryska, Jiří Froněk., and Obsahuje bibliografii
Clinical and experimental studies have repeatedly indicated that overloaded hearts have a higher vulnerability to ischemia/reperfusion injury. The aim of the present study was to answer the question whether the degree of tolerance to oxygen deprivation in hearts of spontaneously hypertensive rats (SHR) may be sex-dependent. For this purpose, adult SHR and their normotensive control Wistar Kyoto (WKY) rats were used. The isolated hearts were perfused according to Langendorff at constant pressure (proportionally adjusted to the blood pressure in vivo). Recovery of contractile parameters (left ventricular systolic, diastolic and developed pressure as well as the peak rate of developed pressure) was measured during reperfusion after 20 min of global no-flow ischemia in 5 min intervals. Mean arterial blood pressure was measured by direct puncture of carotid artery under light ether anesthesia in a separate group of animals. The degree of hypertension was comparable in both sexes of SHR. The recovery of contractile functions in SHR males and females was significantly lower than in WKY rats during the whole investigated period. There was no sex difference in the recovery of WKY animals; on the other hand, the recovery was significantly better in SHR females than in SHR males. It may be concluded that the hearts of female SHR are more resistant to ischemia/reperfusion injury as compared with male SHR. This fact could have important clinical implications for the treatment of cardiovascular disease in women., J. Bešík, O. Szárszoi, J. Kuneš, I. Netuka, J. Malý, F. Kolář, J. Pirk, B. Ošťádal., and Obsahuje bibliografii a bibliografické odkazy