Serum lipid peroxides and total antioxidant status in postmenopausal women on hormone replacement therapy.

Estradiol (E2) has antioxidant properties. The role of progestins in antioxidant defense is still unknown. We have evaluated the influence of E2 and E2 plus medroxyprogesterone acetate (MPA) on serum lipid peroxide (LPO) levels, a marker of free radical reactions, and serum total antioxidant status (TAS) in postmenopausal women. Subjects consisted of 26 women with surgical menopause, before and after 4 months of estrogen replacement therapy (ERT; E2), and 54 women with natural menopause on hormone replacement therapy (HRT; E2 plus MPA). Forty premenopausal women served as a control group. Serum E2 was estimated by radioimmunoassay, follicle-stimulating hormone by IRMA methods, LPO and TAS by colorimetric methods. Before therapy, LPO levels in the postmenopausal women were significantly higher (p < 0.001) than in the control group. After both ERT and HRT, LPO decreased significantly and did not differ between both groups and the control group. TAS was significantly lower in postmenopausal women (p < 0.001) than in the control group before therapy. After both ERT and HRT, TAS increased significantly and did not differ between both groups and the control group. We conclude that oxidative stress is increased after menopause. ERT and HRT inhibit the generation of free radicals and raise antioxidant potential to the levels found in premenopausal women. MPA did not influence the antioxidant action of E2.

Sequencing of caprine alpha-S1 casein cDNAs confirms the accuracy of the RT-PCR approach for detecting of the variants of the gene.

Polymorphism of the casein gene in goats determines milk processing quality and cheese flavour. The main 7 alleles belong to 4 groups: strong alleles A, B, C (which code for 3.6 g/l), medium allele E (1.6 g/1), weak alleles F and D (0.6 g/1) and zero allele, connected with lack of alphaS1 casein in milk. Milk cells (mononuclear milk cells plus epithelium cells) and peripheral blood mononuclear cells were mRNA sources for reverse transcription. Three specific primers were used for polymerase chain reaction, which enabled to differentiate between alleles from four expression groups. The length of PCR products varied since allele F has a 111- nucleotide (nt) deletion of exons 9-11, allele D has a deletion of 36 nt (exon 9), and the medium allele E is associated with a 457 nt insertion in the 19th non-coding exon. Sequencing of amplified fragments, performed on PCR products isolated from milk, confirmed the correctness of the RT-PCR - based alphaS1 casein genotyping method.

Influence of dehydroepiandrosterone on platelet aggregation, superoxide dismutase activity and serum lipid peroxide concentrations in rabbits with induced hypercholesterolemia.

UNLABELLED: Special interest in the role of DHEA dates back to the finding of a correlation between low serum DHEA concentrations and a higher morbidity and mortality rate due to coronary diseases in humans. Animal studies with experimental atherosclerosis confirmed the anti-sclerotic effect of DHEA. The mechanism of DHEA action remains unclear. We determined the influence of dehydroepiandrosterone (DHEA) administration, a potential anti-atherogenic agent, on platelet aggregation, platelet superoxide dismutase (SOD) activity and serum lipid peroxide (LPO) levels in male rabbits fed on a normal and atherogenic diet. 44 adult male New Zealand white rabbits were divided into 4 groups: 1--control group fed on standard rabbit food, 2--fed on an atherogenic diet, 3--fed on an atherogenic diet with DHEA, 4--fed on standard food with DHEA. We detected blood platelet aggregation following (ADP) and collagen activation by means of photometry. Platelet SOD activity was detected by means of fluorometry determining the inhibition of adrenaline auto-oxidation. The serum LPO concentration was measured by means of the colorimetric method. The serum DHEA-S concentration was measured by means of RIA methods, and serum lipid levels were measured by means of Biomérieux manufactured kits. Results demonstrate that (1) elevated LPO concentrations in rabbits with hyperlipidemia did not decrease following DHEA administration. (2) In rabbits fed on a normal diet, DHEA caused a decrease of LPO, which emphasizes the positive influence of this steroid on the oxidative stress in healthy animals. Such a result was not seen in the group with severe hyperlipidemia. (3) Rabbits with hyperlipidemia demonstrated a significantly decreased SOD activity. (4) In healthy animals as well as in those with hyperlipidemia, DHEA administration caused an increase of platelet SOD activity, the main enzyme of the antioxidant defence system, which protects the organism against free radical damage (5) (DHEA had no influence on platelets aggregation in both tested groups). IN CONCLUSION: DHEA administration improves platelet SOD activity, which protects cells against oxidative damage. The hypothesis that DHEA administration leads to an increase in antioxidant potency requires further investigations.

The influence of dehydroepiandrosterone on histology of selected organs in rabbits on an atherogenic diet.

The influence of dehydroepiandrosterone (DHEA) in fodder on the histology of selected organs in rabbits with induced hypercholesterolemia and in healthy rabbits was studied. Rabbits were randomly assigned into four groups: (1) control; (2) atherogenic diet; (3) atherogenic diet with addition of DHEA; (4) normal diet with addition of DHEA. After 12 weeks, the rabbits were bled. Tissue samples were collected, fixed in a 0.4% solution of buffered formalin, dehydrated and embedded in paraffin. Fragments of 5-7 microns were stained with hematoxylin and eosin as well as according to the van Gieson method. Histological analysis showed features of steatosis and intense degenerative changes in analyzed organs of animals from group 2, i.e. liver, kidneys, adrenal glands, lungs and bone. The degenerative changes in the group which in addition to a fat-rich diet received DHEA, were similar to group 2, but much less intense. Histological pictures of organs of the rabbits which received DHEA and normal diet did not differ significantly from the control group. In animals with experimental hyperlipidemia, DHEA acts protectively, decreasing degenerative changes in internal organs caused by an atherogenic diet. DHEA does not change the histological picture of organs in healthy animals.

Effects of homozygosity and stress on blood and bone calcium and magnesium.

SUMMARY: The effect of homozygosity (measured by inbreeding coefficient) on the concentration of serum Ca and Mg ions as well as Mg ions concentrations in whole blood and bone tissue Mg and Ca content was studied. Wild Norway rats (Rattus norvegicus Erxleben) were crossbred with albino outbred rats (Ipf:RIZ). F]-hybrids constituted the control group (0% of inbred). Using full-sibs mating, rats of 50% and 91% of inbred were reproduced. Half of each group was exposed to physical stress (PS) involving 3 d starvation, 3 h swimming and ether anaesthesia (to collect blood for examination), the other half was given only ether anaesthesia (ES). A significant (p < 0,01) linear decrease was observed in the concentration of Ca and Mg ions in serum, of Mg and Ca ions in bone tissue due to homozygosity increase, and a quadratic decrease of Mg content in whole blood. A considerable effect of the sex on Ca and Mg ion concentrations in serum, in particular under the conditions of severe physical stress was observed as well. Physical stress differentiated significantly Mg ion content in whole blood and serum. ZUSAMMENFASSUNG: Die Senkung der Konzentration von Calcium und Magnesium im Blut und im Knochengewebe bei Ratten durch Homozygotie und Streß Bei Ratten unterschiedlichen Inzuchtgrades (%): 0, 59 und 91 wurden unter physischem Streß (3 Tage Hungern und 3 h Schwimmen) mittels RIA die Konzentrationen von Calcium und Magnesium Ionen im Blutserum, Mg im ganzen Blut und Mg und Ca im Knochengewebe untersucht. Der Ausgangselternbestand (0% Inzucht) waren F(1) -Kreuzungen von wilden Wanderratten (Rattus norvegius Erxleben) mit Albino Ratten der nichtverwandten Linie Ipf:RIZ. Es wurde statistisch signifikante lineare Senkung der Konzentration von Ca und Mg Ionen im Blutserum, von Mg und Ca im Knochengewebe sowie (P ≤ 0,01) der Mg Konzentration im ganzen Blut unter dem Einfluß der Inzucht gefunden. Letztere folgt einem Polynom 2. Grades. Es wurde auch ein signifikanter Einfluß von Geschlecht auf Ca und Mg Ionen Konzentration im Blutserum, besonders bei dem starken physischen Streß, beobachtet. Der physische Streß hat großen Einfluß (P ≤ 0,01) auf Mg Konzentration im Blutserum sowie im ganzen Blut.

The effect of genetic variability (degree of homozygosity) on serum levels of the anterior pituitary hormones prolactin, corticotropin, and growth hormone in rats.

Male and female wild Norway rats (Rattus norvegicus Erxleben) and males and female albino outbred rats (Ipf:RIZ) were crossbred. The resulting animals (F1 hybrids) were the control, noninbred group (0% inbred). By systematic full-sib mating, two experimental groups (50 and 91% of inbred) were produced. Half of each group (both males and females) was exposed to physical stress (3 days of starvation and 3 hr of swimming). The other half of each group was anesthetized using ether to collect blood. The anterior pituitary hormone concentrations of prolactin (PRL), corticotropin (ACTH), and growth hormone (rGH) in blood serum were determined by the radioimmunoassay method. Significant relationships between the PRL, ACTH, and rGH concentrations in blood serum and the inbreeding coefficient were observed: A significant PRL content decrease in blood serum occurred (linear function) and the rGH and ACTH content diminished significantly rapidly (quadratic function). These changes were affected by an increase in homozygosity. Stress significantly influenced PRL, ACTH, and rGH concentrations as well. The sex of rats significantly determined PRL and ACTH content only. Hormone levels were also influenced by interactions between the factors studied (inbred level, sex, stress).

The relationship between homozygosity level and animal physiology: iron content of plasma and whole blood as well as total iron binding capacity by transferrin (TIBC) in rats of various inbreeding coefficient.

Male and female wild Norway rats (Rattus norvegicus Erxleben) and male and female albino outbred rats (Ipf:RIZ) were crossbred. These animals were the control, noninbred group (0% inbred). By systematic full-sib mating, two experimental groups (50 and 91% of inbred) were raised. Half of each group (both males and females) was exposed to physical stress (3 days of starvation and 3 hr of swimming). The other half of each group was ether anesthetized to collect blood. The iron content of plasma and whole blood, as well as the total iron binding capacity, was determined by the Atom-Spec method. A significant decrease in the iron content of plasma and whole blood as well as the TIBC was observed by an increase in the inbreeding coefficient. Stress significantly influenced the iron content of plasma and whole blood as well as the TIBC, whereas the sex of the rats affected the whole-blood iron concentration and TIBC. Moreover, some double interactions had an impact on the iron content and TIBC. The interactions were as follows: plasma--inbreeding level and stress; whole blood--sex and stress; and TIBC--inbreeding level and sex.