Effect of iron oxide nanoparticles on vascular function and nitric oxide production in acute stress-exposed rats.

We investigated whether polyethylene glycol-coated Fe3O4 nanoparticles (IONs), acute stress and their combination modifies vascular functions, nitric oxide synthase (NOS) activity, mean arterial pressure (MAP) as well as hepcidin and ferritin H gene expressions in Wistar-Kyoto rats. Rats were divided into control, ION-treated rats (1 mg Fe/kg i.v.), repeated acute air-jet stress-exposed rats and IONs-and-stress co-exposed rats. Maximal acetylcholine (ACh)-induced and sodium nitroprusside (SNP)-induced relaxations in the femoral arteries did not differ among the groups. IONs alone significantly elevated the N?-nitro-L-arginine methyl ester (L-NAME)-sensitive component of ACh-induced relaxation and reduced the sensitivity of vascular smooth muscle cells to SNP. IONs alone also elevated NOS activity in the brainstem and hypothalamus, reduced NOS activity in the kidneys and had no effect in the liver. Acute stress alone failed to affect vascular function and NOS activities in all the tissues investigated but it elevated ferritin H expression in the liver. In the ION-and-stress group, NOS activity was elevated in the kidneys and liver, but reduced in the brainstem and hypothalamus vs. IONs alone. IONs also accentuated air-jet stress-induced MAP responses vs. stress alone. Interestingly, stress reduced ION-originated iron content in blood and liver while it was elevated in the kidneys. In conclusion, the results showed that 1) acute administration of IONs altered vascular function, increased L-NAME-sensitive component of ACh-induced relaxation and had tissue-dependent effects on NOS activity, 2) ION effects were considerably reduced by co-exposure to repeated acute stress, likely related to decrease of ION-originated iron in blood due to elevated decomposition and/or excretion.

The effect of different wavelengths of light during incubation on the development of rhythmic pineal melatonin biosynthesis in chick embryos.

Rhythmic pineal melatonin biosynthesis develops in chick embryos incubated under a light (L)-dark (D) cycle of polychromatic white light. The spectral sensitivity of the embryonic pineal gland is not known and was investigated in this study. Broiler breeder eggs (Ross 308, n=450) were incubated under white, red, green or blue light under the 12L : 12D cycle. Melatonin was measured in extracts of pineal glands by radioimmunoassay. The daily rhythm of pineal melatonin levels in 20-day-old chick embryos was confirmed during the final stages of embryonic life under all four wavelengths of light with expected higher concentrations during dark- than light-times. The highest pineal melatonin levels were determined in chick embryos incubated under red and white light and lower levels under green light. The incubation under blue light resulted in the lowest melatonin biosynthesis. Pineal melatonin concentrations increased substantially on post-hatching day two compared with pre-hatching levels and we did not find differences between birds incubated and kept in either white or green light. Our results demonstrate a selective sensitivity of the chick embryo pineal gland to different wavelengths of light. Rhythmic melatonin production is suggested as a possible mechanism, which transfers information about the quality of ambient light to the developing avian embryo.

Effect of exogenous testosterone on oxidative status of the testes in adult male rats.

The aim of this study was to investigate the testosterone-induced changes in the oxidative status of testes in adult male rats treated either with testosterone or after blockade of androgen receptors with cyproterone acetate. A total of 40 intact rats were divided into four groups: a control group receiving sterile oil, the testosterone group receiving testosterone isobutyras, the cyproterone group receiving cyproterone acetate and the combination group receiving both testosterone isobutyras and cyproterone acetate. Treatments were carried out for 2 days by intramuscular application. Parameters of oxidative stress and the expression levels of the steroidogenic acute regulatory protein (StAR) gene were measured in testes. Significantly increased TBARS and advanced glycation end products (AGEs) levels were found in the testosterone group when compared to the control group. The °1 ferric-reducing ability of the tissue and total antioxidative capacity were lower in the testosterone group in comparison with the control group. Gene expression analysis revealed significant downregulation of the StAR gene in the testes of rats in the testosterone and combination groups with respect to control animals. In conclusion, administration of exogenous testosterone influences the lipid peroxidation and carbonyl stress and decreases the antioxidant defence in the testes. These data might have implications for male fertility in humans.

Effect of long-term simulated microgravity on some sexual traits of male Japanese quail.

The aim of this study was to investigate the effects of long-term stay of Japanese quail in simulated microgravity on some sexual features of males. As a model for simulating microgravity exposure of birds in laboratory conditions was used hypodynamia. The mean left testis weight in males reared under hypodynamia from day 3 up to 180 days of age was lower than that of control (P<0.05), but the right testis weight differences between both groups were not significant. Also the area, volume and foam production of cloacal gland was not significantly decreased in hypodynamia birds at the end of experiment. By contrast, the plasma testosterone concentration of males living in hypodynamia was reduced about 50 % at 90 and 180 days of age in comparison to control (P<0.05) suggesting some negative effects on sexual development. Our results demonstrated that male quail kept under simulated microgravity conditions were sexually competent although their sexual efficiency was reduced especially in terms of plasma testosterone.