Effect of anabolic steroid nandrolone decanoate on the properties of certain enzymes in the heart, liver, and muscle of rats, and their effect on rats' cardiac electrophysiology.

Nandrolone decanoate (ND) is an anabolic steroid, modified to enhance anabolic rather than androgenic actions. The physiological effects of ND treatment are often used in various aspects of medical practice. In this investigation we have tried to establish whether a single, high dose of ND (20 mg/kg) would cause any anabolic effects. Moreover, we have attempted to correlate the eventual effects with changes in the activity and kinetic properties of anabolic- and bioenergetic-involved enzymes in different tissues of rats, along with the rats' ECG parameters. The body and liver weights of the rats were unchanged, but heart weight had increased 10 days after ND injection. Electrocardiographic data showed a small prolongation of the QRS complex 3, 6, and 10 days after ND treatment. It was established that ND causes activation of glucose-6-phosphate and 6-phosphogluconate dehydrogenases, malic enzyme, and NADP-linked isocitrate dehydrogenase in rat hearts. Moreover, 6-phosphogluconate dehydrogenase from the hearts of ND-treated rats showed higher affinity to its substrate, in comparison with control. Activation of transketolase by ND in the liver was accompanied by inhibition of glucose-6-phosphate and 6-phosphogluconate dehydrogenases. We observed an increase of glucose 6-phosphate dehydrogenase and NAD-linked malate dehydrogenase in the muscle of ND treated rats. It may be concluded that ND in a single high dose exhibits cardiotrophic action, especially towards the increase of heart dehydrogenases activity which generates NADPH and supplies ribose phosphate for the biosynthesis of nucleotides and nucleic acids. On the other hand, ND may cause activation of ATP synthesis in muscle by enhanced malate-aspartate shuttle action.

MHC-DRB3 variation in a free-living population of the European bison, Bison bonasus.

MHC genes play a crucial role in pathogen recognition and are the most polymorphic genes in vertebrates. Loss of variation in these genes in bottlenecked species is thought to put their survival at risk. We examined variation at the MHC II DRB3 locus in the European bison, Bison bonasus, a species that has undergone an extreme bottleneck: the current population originated from only 12 founders. We also tested for the association of DRB3 genes with the incidence of posthitis, a disease affecting the reproductive organs of bulls and posing a new threat to the survival of the species. We found very limited MHC diversity, with only four alleles segregating in a sample of 172 individuals from a free-ranging Bialowieza population. The alleles were highly divergent and revealed the hallmark of positive selection acting on them in the past, that is, a significant excess of nonsynonymous substitutions. This excess was concentrated in putative antigen-binding sites, suggesting that selection was driven by pathogens. However, we did not observe departures from Hardy-Weinberg equilibrium, an indicator of strong ongoing selection. Neither have we found a significant association between DRB3 alleles or genotypes and susceptibility to posthitis. Alleles conferring resistance to males may have been lost during the extreme bottleneck the species had undergone.