[Increase in the concentration of sEH protein in renal medulla of ISIAH rats with inherited stress-induced arterial hypertension].

The concentration of soluble epoxide hydrolase (sEH) protein was studied in renal medulla of adult rats from hypertensive ISIAH strain and normotensive WAG strain. The sEH is a key enzyme in metabolism of epoxyeicosatrienoic acids capable of activating endothelial NO-synthase and nitrogen oxide formation, and therefore being vasodilators. An increase in the sEH protein concentration (that we found) allows one to assume that the oxidative stress is increased in the renal medulla of hypertensive rats, and the bloodflow is decreased.

[Expression of Catechol-O-Methyltransferase (Comt), Mineralocorticoid Receptor (Mlr), and Epithelial Sodium Channel (ENaC) Genes in Kidneys of Hypertensive ISIAH Rats at Rest and during Response to Stress].

Emotional stress plays a significant role in the processes of the development of arterial hypertension, especially in the presence of genetic predisposition. The origin and maintenance of hypertensive status during stress development can be activated by the sympathetic nervous system. An increase in sympathetic stimulation can, in turn, result in a change in the functions of kidneys, which provide fluid and electrolyte balance of the organism. A comparative study of the mRNA expression level of catechol-o-methyltransferase (Comt), mineralocorticoid receptor (Mlr), and ß-subunit of epithelial sodium channel (ß-ENaC) genes was conducted on the kidneys of hypertensive ISIAH rats and normotensive WAG rats at rest and after the effect of emotional stress. The discovered changes in the expression level of the selected genes confirm their involvement in increased sympathetic stimulation of the kidney, along with changes in the function of kidney regulation of fluid and electrolyte balance, which is an important factor of the development of sustained hypertension in the ISIAH rats strain.

Cryopreservation and In Vitro culture of Preimplantation Embryos in Djungarian Hamster (Phodopus sungorus).

Although embryo cryobanking was applied to Syrian golden and to Campbell's hamsters, no attempt has been made at freezing embryos in Djungarian hamsters. Four-cell stage embryos were flushed from the reproductive ducts of pregnant females before noon of the third-day post coitum and frozen in 0.25-ml straws according to standard procedures of slow cooling. A mixture of permeating (ethylene glycol) and non-permeating (sucrose) cryoprotectants was used. The thawing was performed by incubating at RT for 40 s followed by 40 s in a water bath at 30.0°C. Most (66.7%) of the non-frozen four-cell embryos developed up to the morula stage in rat one-cell embryo culture medium (R1ECM). The use of hamster embryo culture medium (HECM) yielded fewer morulas (18.2%) during the same 24-h period of culture. The rate of embryo's surviving the freezing-thawing procedures, as estimated by light microscopy, was 60.7-68.8%. After 24-h culturing in R1ECM, 64.7% of frozen-thawed four-cell embryos developed and all of them reached the morula stage. Supplementation of R1ECM with GM-CSF (2 ng/ml) improved the rate of Djungarian hamster frozen-thawed embryo development: 100% of the four-cell stage embryos developed, 50% of them achieved the morula stage, and 50% developed even further and reached the blastocyst stage within 24 h of culturing. This study reports the world's first successful transfer of frozen-thawed Djungarian hamster embryos yielding term pups. Taken together, the results of this study demonstrate the possibility of applying some key reproductive technologies, that is, embryo freezing/cryopreservation and in vitro culture, to Djungarian hamsters.

[Genetic loci for spleen weight and blood pressure in Isiah rats with inherited stress-induced arterial hypertension].

Recently, the important role of the spleen function in hypertension development was demonstrated. In this study, the genetic control of absolute and relative spleen weight was investigated to reveal the genetic loci common for spleen traits and for arterial blood pressure at rest and under the emotional stress conditions in the ISIAH rats with inherited stress-induced arterial hypertension. The search for genetic loci for absolute and relative spleen weight was performed on 6-month old F2 (ISIAH x WAG) hybrid males derived from a cross of hypertensive ISIAH and normotensive WAG rats. One significant QTL mapped on chromosome 1 and 5 suggestive loci were found for relative spleen weight. Four suggestive loci were detected for absolute spleen weight. All detected loci were novel. The significant QTL on chromosome 1 was common for relative spleen weight and arterial blood pressure at rest and under the emotional stress conditions in ISIAH rats. The results suggest that the manifestation ofthe stress-sensitive arterial hypertension in ISIAH rats may be related to the changes in genetic control of the spleen function.

[Enhanced expression of EPHX2 gene in the kidney of the hypertensive ISIAH rats].

Epoxyeicosatrienoic acids (EETs) have antihypertensive properties and play a part in the maintenance of renal microvascular function. EETs mediate vasodilation of rat preglomerular microvessels and activate ion channels. Ephx2 is coding for the soluble epoxide hydrolase (sEH) which catalyze the degradation of EETs. Renal cortex and renal medulla were tested for Ephx2 mRNA level in hypertensive ISIAH and normotensive WAG rats at rest and emotional stress conditions. The microarray analysis and real-time PCR were used to assess the transcriptional activity of Ephx2. Enhanced transcriptional activity of Ephx2 in both renal structures of ISIAH rats was found at rest and stress conditions. The emotional stress caused elevation of Ephx2 mRNA level in renal medulla of ISIAH rats and opposite response--a decrease in Ephx2 expression in the renal medulla and cortex of WAG rats.The results suggest Ephx2 participation in the control of the vascular tone changes in kidney promoting the hypertensive state in the ISIAH rats.

[EFFECTS OF IN VITRO CULTURE AND EMBRYO TRANSFER ON THE ARTERIAL BLOOD PRESSURE, BODY WEIGHT AND BEHAVIOUR IN ISIAH RATS].

This study was the first to investigate long-term effects of in vitro culturing of embryos combined with their cryopreservation and transfer on arterial blood pressure, body weight and behavior in hypertensive rats. No differences in body weight and arterial blood pressure levels were found between the naturally born rats and those born with the help of ART (assisted reproductive technologies). However, ART-born rats spent more time on rearing, as was revealed by the open-field test. The results of the elevated plus maze test indicated that these rats spent more time in the open arms and demonstrated a longer duration of head dips. Moreover, the light-dark box test showed a longer total leaning-out time in this group. Taken together, the results of the three behavioral tests demonstrate a greater exploratory activity and lower anxiety in ART-born ISIAH rats than in natural born ones.