Effects of dehydroepiandrosterone on passive avoidance in ovariectomized female rats of different age

The aim of the present work was to study the influence of long-term treatment with dehydroepiandrosterone (DHEA) in doses of 0.1 and 0.7 mg/kg, i.p. on the passive avoidance performance in the ovariectomized female rats of 5- and 18-month old. The results obtained indicated that DHEA administration during 7 days in dose of 0.1 mg/kg normalized the passive avoidance performance in the ovariectomized rats of 5-month old while DHEA administration during 7 days in dose of 0.7 mg/kg restored passive avoidance performance in the ovariectomized rats of 18-month old.     

Effect of alpha-tryptophan on conditioning and behavior in rats with experimental pathology of the thyroid gland

Effects of L-tryptophan on learning and behavior were studied in male rats with a deficit or excess of thyroid hormones. Learning was assessed in active avoidance paradigm, and behavior was estimated in the "open-field" test. It was found that L-tryptophan restored the capability of thyreoidectomized rats for acquisition and reproduction of the active avoidance reaction and increased the exploratory behavior of these rats in the open-field. In triiodothyronine treated rats, L-tryptophan eliminated a light stimulatory effects of thyroid hormones on the processes of formations and retention of the active avoidance reaction, increased the exploratory activity, but decreased grooming in the open-field.     

Involvement of 5-HT1A receptors in passive avoidance learning in intact and ovariectomized female rats

The influence of chronic administration of 5-HT1A receptor agonist 8-OH-DPAT (0.05 mg/kg, s.c.) and 5-HT1A receptor antagonist NAN-190 (0.1 mg/kg, i.p.) injected for 14 days alone or in combination with 17beta-estradiol (0.5 microg i.m./rat/day) was studied on passive avoidance performance (PAR) and on behavior in the open field test in adult intact and ovariectomized (OVX) female rats. Administration of 5-HT1A receptor antagonist NAN-190 alone significantly improved PAR (p<0.05) in intact females with proestrus and estrus and in OVX females. Administration of 5-HT1A receptor agonist 8-OH-DPAT alone or in combination with 17beta-estradiol significantly (p<0.05) improved PAR in OVX rats and failed to normalize PAR in intact rats with proestrus and estrus. Results of the work specify the involvement of 5-HT1A receptors in the mechanisms of passive avoidance learning in OVX female rats.     

Retention of plastic-tipped dart tags in African tigerfish Hydrocynus vittatus

Estimates of tag retention and tagging-related mortality are essential for mark-recapture experiments. Mortality and tag loss were estimated from 15 tigerfish Hydrocynus vittatus marked using Hallmark model PDL plastic-tipped dart tags released into a 1 730 m² pond at Kamutjonga Inland Fisheries Institute, Namibia, and inspected bi-monthly for the presence or absence of tags. No mortality was observed during the experiment. All marked fish had lost their tags after 10 months and 50% tag loss was estimated at 3.9 months. The high tag loss rate indicates that PDL plastic-tipped dart tags are not suitable for long-term studies on this species.     

Natural history of SLC11 genes in vertebrates: tales from the fish world

Background  

The SLC11A1/Nramp1 and SLC11A2/Nramp2 genes belong to the SLC11/Nramp family of transmembrane divalent metal transporters, with SLC11A1 being associated with resistance to pathogens and SLC11A2 involved in intestinal iron uptake and transferrin-bound iron transport. Both members of the SLC11 gene family have been clearly identified in tetrapods; however SLC11A1 has never been documented in teleost fish and is believed to have been lost in this lineage during early vertebrate evolution. In the present work we characterized the SLC11 genes in teleosts and evaluated if the roles attributed to mammalian SLC11 genes are assured by other fish specific SLC11 gene members.     

Changes in the lymphoid tissue and in the level of corticosteroids in staphylococcal intoxication and infection]

A complex quantitative study of changes of proliferative processes in lymphatic vessels on the one hand and changes of the level of corticosteroids in the peripheral blood in staphylococcal intoxication and infection in the same rats on the other hand has been carried out. In the work H3-thymidine has been used. The comparison of the obtained morphological data with the dynamics of the change in the corticosteroid level shows that the decay of lymphocytes, the devastating of light centers and the cortical substance of lymph nodes, an abrupt lowering of the amount of DNA-synthesizing and mitotically dividing cells take place in the period associated with a release of a great amount of corticosteroids into the blood. The drop of their level to control values goes in parallel with increasing the amount of DNA-synthesizing and mitotically dividing cells. The obtained data suggest that the leading role in those changes of the lympoid tissue which had been described by a number of authors in infectional processes is played by corticosteroids.