Effects of GABA(A) receptor modulation on the expression of GnRH gene and GnRH receptor (GnRH-R) gene in the hypothalamus and GnRH-R gene in the anterior pituitary gland of follicular-phase ewes

The effect of prolonged, intermittent infusion of GABA(A) receptor agonist (muscimol) or GABA(A) receptor antagonist (bicuculline) into the third cerebral ventricle on the expression of GnRH gene and GnRH-R gene in the hypothalamus and GnRH-R gene in the anterior pituitary gland was examined in follicular-phase ewes by real-time PCR. The activation or inhibition of GABA(A) receptors in the hypothalamus decreased or increased the expression of GnRH and GnRH-R genes and LH secretion, respectively. The present results indicate that the GABAergic system in the hypothalamus of follicular-phase ewes may suppress, via hypothalamic GABA(A) receptors, the expression of GnRH and GnRH-R genes in this structure. The decrease or increase of GnRH-R mRNA in the anterior pituitary gland and LH secretion in the muscimol- or bicuculline-treated ewes, respectively, is probably a consequence of parallel changes in the release of GnRH from the hypothalamus activating GnRH-R gene expression. It is suggested that GABA acting through the GABA(A) receptor mechanism on the expression of GnRH gene and GnRH-R gene in the hypothalamus may be involved in two processes: the biosynthesis of GnRH and the release of this neurohormone in the hypothalamus.     

Synthesis, antitumor and anti-HIV activities of benzodithiazine-dioxides

Several 8-chloro-7-R1-6-R2-3-R3-imidazo[1,2-b][1,4,2]benzodithiazine 5,5-dioxide derivatives (9-11, 16-19, and 21-24) have been synthesized as potential antitumor or anti-HIV agents. The in vitro antitumor and anti-HIV-1 activities of the compounds were determined in a panel of cell lines. The benzodithiazine-dioxide 10 showed 50% growth inhibitory activity in low micromolar against most cells. It was particularly effective in leukemia, lung, melanoma, ovarian, and renal cancer cells with GI50 values of 1-2 microM. Interestingly, benzodithiazine-dioxide 16 showed remarkable anti-HIV-1 activity with 50% effective concentration EC50 value of 0.94 microM and no significant cytotoxicity at 200.0 microM.     

Age-related changes of selected blood biochemical indicators in dairy calves during their first week of life

The aim of this study was to determine the influence of age and ingested food (colostrum and mature milk) on the concentrations of selected blood biochemical components connected with nitrogen and mineral metabolism in dairy calves during their first week of life. The experiment was carried out on 13 Polish Black and White breed dairy calves. The animals were fed colostrum within the first 3 days of postnatal life and thereafter the mature milk of their dams until the end ofthe experiment (7 days). The obtained results showed that intensive catabolic and anabolic changes in nitrogen occur in the first week of life. These changes were particularly intense during the first 24-48 hours of life and may reflect dynamic tissue remodelling. The results of this experiment also show that healthy calves efficiently regulate water and electrolyte homeostasis.     

Synthesis,structural characterization and in vitro antitumor activity of novel 6-chloro-1,1-dioxo-1,4,2-benzodithiazie derivatives

A series of nonconventional aminium N-(6-chloro-7-R-1,1-dioxo-1,4,2-benzodithiazin-3-yl)arylsulfonamidates 7-15 have been synthesized by the reactions of 6-chloro-7-R-3-methylthio-1,4,2-benzodithiazine 1,1-dioxides with 4-dimethylaminopyridine or Et(3)N and some arylsulfonamides. The free N-(6-chloro-7-methyl-1,1-dioxo-1,4,2-benzodithiazin-3-yl)benzenesulfonamides 16-18 were obtained by treatment of their aminium salts with H(2)SO(4) in boiling acetic acid. The in vitro antitumor activity of the compounds 9, 11-14 and 16-18 has been tested in the antitumor screening of the National Cancer Institute (NCI), and relationships between structure and antitumor activity are discussed. 4-Dimethylaminopyridinium 4-chloro-N-(6-chloro-7-methyl-1,1-dioxo-1,4,2-benzodithiazin-3-yl)benzenesulfonamidate 9 is the prominent of the compounds due to its remarkable activity (log GI(50)<-8.00, log TGI=-5.50) and selectivity for the leukemia SR cell line. For that reason experimental and theoretical analysis of the geometric and electronic properties of 9 was carried out.     

Interspecific differences in root architecture among maize and triticale genotypes grown under drought,waterlogging and soil compaction

Environmental stresses (soil compaction, drought, waterlogging) cause changes in plants’ root system structure, also affecting the growth of above-ground parts. The aim of this study was to estimate phenotypic variation among maize and triticale genotypes in root penetration ability through petrolatum-wax-layer (RPA). Also, the effect of shortage or excess of soil water on dry matter of shoots and roots and morphological changes in root system structure in sensitive and resistant maize and triticale genotypes grown in low or high soil compaction level was evaluated. To estimate RPA index, the petrolatum-wax-layer method (PWL) was used. The strength of three petrolatum-wax concentrations 60, 50 and 40 % was 0.52, 1.07 and 1.58 MPa, respectively. High coefficients of variation (CV) were observed in 0.52 and 1.07 MPa and for maize were 19.2 and 21.7 %, and for triticale, 12.5 and 18.3 %, respectively. The data indicate that the use of PWL technique is an effective screening method, and makes it possible to divide the genotypes into resistant and sensitive groups. The second part of this study investigated a multistress effect of soil compaction combined with drought or waterlogging on root and shoot growth and morphological changes in root system structure of maize and triticale genotypes differing in susceptibility to environmental stresses. Seedlings were grown for 4 weeks in root-boxes under conditions of low (LSC 1.1 g cm^?3) or severe (SSC 1.6 g cm^?3) soil compaction. Drought or waterlogging stresses were applied for 2 weeks from 14th to 28th day. In comparison to LSC treatment, in SSC treatment the decrease in dry matter of shoots and roots was greater for sensitive genotypes of maize and triticale (Ancora, CHD-147). Soil drought or waterlogging caused greater decrease of dry matter of shoots and roots in seedlings grown in SSC in comparison to LSC. The root penetration index (RPI) was estimated as a ratio of root dry matter in 15–40 cm root-box layer to total root dry matter. On the basis of RPI it was possible to group the genotypes according to their ability to distribute roots in soil profile. In comparison to LSC, SSC exerted a strong influence on the length of seminal and seminal adventitious roots, as well as the number and length of L- and S-type lateral roots developed on seminal and nodal roots. In both species the restriction effect of soil compaction on number and length of roots was more severe in sensitive (Ankora, CHD-147) than in resistant (Tina, CHD-247) genotypes. The restriction in roots propagation was greater in triticale than in maize. Exposure to drought or waterlogging in the case of genotypes grown in LSC and SSC treatments caused a decrease in number and length of particular components of root system structure. In both species the decrease of root number and length in plants grown under waterlogging was greater than under drought. The observed changes in root system were greater in sensitive (Ankora, CHD147) than in resistant (Tina, CHD-247) genotypes. Statistically significant correlations were found between RPA and RPI and also between these indexes and soil compaction, drought and waterlogging susceptibility indexes. This indicates that genotypes resistant to soil compaction were resistant to drought or waterlogging and also that genotypes resistant to drought were resistant to waterlogging.     

Desiccation tolerance acquisition in developing beech (Fagus sylvatica L.) seeds: the contribution of dehydrin-like protein

The acquisition of desiccation tolerance (DT) in developing beech (Fagus sylvatica L.) seeds and the role of a dehydrin protein in this process were investigated. DT was determined by measurement of electrolyte leakage and germination capacity after drying to 10–12% moisture content (MC). In addition to mass maturity, the presence of heat-stable proteins, dehydrin accumulation and the peak of ABA content were measured in relation to the acquisition of DT. Mass maturity was achieved at 16 weeks after flowering (WAF). The germination capacity increased from 8% at 12 WAF to 80–90% after 16 WAF. Cell membrane integrity, measured as a decrease in electrolyte leakage after desiccation, was acquired at 16 WAF. Additionally, the ratio of heat-stable to soluble proteins was the highest at 16 WAF. One dehydrin-like protein with a molecular mass 44 kDa, named DHN44, was detected in embryonic axes at 16 WAF and in cotyledons at 17 WAF, and its gradual accumulation was observed in mature seeds. With regard to the acquisition of DT, the strongest correlations were detected between electrolyte leakage, DHN44 accumulation, and the percentage of heat-stable proteins. These results suggest that developing beech seeds become tolerant to desiccation at 16 WAF. The effect of desiccation and ABA treatment on DHN44 synthesis was tested before (14 WAF) and after the DT acquisition (18 WAF). Depending on the maturation stage desiccation and ABA treatment can induce or enlarge DHN44 expression.     

Coordination abilities of neurokinin A and its derivative and products of metal-catalyzed oxidation

The classical tachykinins, substance P, neurokinin A and neurokinin B are predominantly found in the nervous system where they act as neurotransmitters and neuromodulators. Significantly reduced levels of these peptides were observed in neurodegenerative diseases and it may be suggested that this reduction may also result from the copper(II)-catalyzed oxidation. The studies of the interaction of copper(II) with neurokinin A and the copper(II)-catalyzed oxidation were performed. Copper(II) complexes of the neurokinin A (His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH₂) and acetyl-neurokinin A (Ac-His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH₂) were studied by potentiometric, UV-Vis (UV-visible), CD (circular dichroism) and EPR spectroscopic methods to determine the stoichiometry, stability constants and coordination modes in the complexes formed. The histidine residue in first position of the peptide chain of neurokinin A coordinates strongly to Cu(II) ion with histamine-like {NH₂, N_Im} coordination mode. With increasing of pH, the formation of a dimeric complex Cu₂H₂L₂ was found but this dimeric species does not prevent the deprotonation and coordination of the amide nitrogens. In the Ac-neurokinin A case copper(II) coordination starts from the imidazole nitrogen of the His; afterwards three deprotonated amide nitrogens are progressively involved in copper coordination. To elucidate the products of the copper(II)-catalyzed oxidation of the neurokinin A and Ac-neurokinin A, liquid chromatography-mass spectrometry (LC-MS) method and Cu(II)/hydrogen peroxide as a model oxidizing system were employed.Oxidation target for both studied peptides is the histidine residue coordinated to the metal ions. Both peptides contain Met and His residues and are very susceptible on the copper(II)-catalyzed oxidation.     

HPLC method for determination of fluorescence derivatives of cortisol,cortisone and their tetrahydro- and allo-tetrahydro-metabolites in biological fluids

11β-Hydroxysteroid dehydrogenase isoform 2 (11β-HSD2) is responsible for conversion of cortisol (F) to inactive cortisone (E). Disturbance of its activity can cause hypertension. To estimate 11β-HSD2 activity, besides F and E, their tetrahydro- (THF, THE) as well allo-tetrahydro- (allo-THF, allo-THE) metabolites should be determined. This study describes HPLC-FLD method for the quantitative determination of endogenous glucocorticoids (GCs) in plasma and urine (total and free) and their metabolites in urine. Following extraction at pH 7.4 using dichloromethane, GCs (F, E, THF, allo-THF, THE, allo-THE and internal standard – prednisolone) were derivatized with 9-anthroyl nitrile and purified by SPE using C₁₈ cartridges. The enzymatic hydrolysis of conjugated steroids was provided using β-glucuronidase. The influence of organic bases on 9-AN derivatization of steroids was investigated. The best yield of the derivatization was obtained in presence of the mixture of 10.0% triethylamine (TEA) and 0.1% quinuclidine (Q). Chromatographic separation was accomplished in the Chromolith RP-18e monolithic column. The elaborated method was validated. Calibration curves were linear in the ranges: for F, E and THF 5.0–1000.0 ng mL^?1, for allo-THF and THE + allo-THE 10.0–1000.0 ng mL^?1. LOD (S/N = 3:1) for all analytes amounted 3.0 ng mL^?1. Recoveries of GCs exceeded 90%. The method was precise and accurate, intra- and inter-day precision were 3.0–12.1% and 9.2–14.0%, respectively. Accuracy ranged from 0.2 to 15.1%. The method was applied for estimating endogenous GCs in plasma and urine. Plasma levels of F and E were in the ranges: 133.0–174.5 ng mL^?1 and 17.4–35.9 ng mL^?1, respectively. Free urinary steroids were in the ranges: 12.0–54.1 μg/24 h (UFF) and 37.8–76.2 μg/24 h (UFE). The ratio of (THF + allo-THF)/(THE + allo-THE) amounted from 1.01 to 1.23. The obtained results confirmed utility of the elaborated method in the assessment of 11β-HSD2 activity in man.     

The role of GABA(A) and GABA(B) receptors in the control of GnRH release in anestrous ewes

The paper reviews data concerning the involvement of GABA(A) and GABA(B) receptors in the control of GnRH secretion in anestrous ewes. Generally, GABA influences the GnRH release through GABA(A) and GABA(B) receptors located on perikaria of the GnRH neurons in the preoptic area (MPOA) or through the influence on beta-endorphinergic and catecholaminergic systems activity in MPOA and in ventromedial-infundibular region of the hypothalamus (VEN/NI). Stimulation of GABA(A) receptors in VEN/NI and MPOA attenuates GnRH release, while activation of GABA(B) receptors in MPOA decreases GnRH secretion, and in VEN/NI increases concentration of GnRH. The different neural mechanisms could be involved in this process: direct ligand action on the GABA(A) and GABA(B) receptors located on GnRH cells and axon terminals or indirect effect through the changes in the beta-endorphinergic and catecholaminergic systems activity in these structures of the brain.     

Changes in the activity of some lysosomal enzymes and in the fine structure of submandibular gland due to experimental diabetes

The aim of this study was to establish and quantify changes in the activities of the some lysosomal enzymes and to determine the type of changes in the ultrastructure of the submandibular gland in rabbits caused during progression of diabetes. The experiment was conducted on 89 New Zealand rabbit males. Diabetes was induced by the intravenous administration of 10% alloxan solution at a dose of 10-mg/kg-body weight. On the seventh day after alloxan administration, the level of glucose in blood was determined. Rabbits were divided into five groups: intact (n=18), 21-day diabetes (n=18), 42-day diabetes (n=17), 90-day diabetes (n=19) and 180-day diabetes (n=17). From killed animals in each group, the submandibular glands were removed and fixed or stored. Enzyme activities were assayed by spectrophotometric methods using substrates (Sigma) which release 4-methyloumbeliferol when they react with the proteases. Fixation procedure was done according to standard methods. Semi-thin and ultra-thin specimens were prepared by use of clearly visible after 42 days of diabetes. Mitochondria were damaged, accumulation of large amounts of lipids in the intracellular spaces was observed. After 90 days the presence of vacuoli and swollen lysosomes were observed, some cells also contained myelin figures. After 180 days the greatest changes were observed in the blood vessels, which had thickened walls and were often occluded. We concluded that the total activity of acid phosphatase and beta-N-acetyl-glucosaminidase in the submandibular gland was correlated with the level of glucose but there was no correlation between total beta-galactosidase activity and the serum concentration level of glucose has been detected during course of diabetes. The activities of the free fractions of acid phosphatase, beta-galactosidase and beta-N-acetyl-glucosaminidase in the submandibular gland were higher than the bound fractions in all groups of rabbits. The changes in the ultrastructure of the submandibular gland were correlated with changes in serum glucose level and with lysosomal enzymes activities during progression of experimental diabetes in rabbits.