Long-term melatonin treatment reduces ovarian mass and enhances tissue antioxidant defenses during ovulation in the rat

Melatonin regulates the reproductive cycle, energy metabolism and may also act as a potential antioxidant indoleamine. The present study was undertaken to investigate whether long-term melatonin treatment can induce reproductive alterations and if it can protect ovarian tissue against lipid peroxidation during ovulation. Twenty-four adult female Wistar rats, 60 days old (± 250-260 g), were randomly divided into two equal groups. The control group received 0.3 mL 0.9% NaCl + 0.04 mL 95% ethanol as vehicle, and the melatonin-treated group received vehicle + melatonin (100 µg·100 g body weight-1·day-1) both intraperitoneally daily for 60 days. All animals were killed by decapitation during the morning estrus at 4:00 am. Body weight gain and body mass index were reduced by melatonin after 10 days of treatment (P < 0.05). Also, a marked loss of appetite was observed with a fall in food intake, energy intake (melatonin 51.41 ± 1.28 vs control 57.35 ± 1.34 kcal/day) and glucose levels (melatonin 80.3 ± 4.49 vs control 103.5 ± 5.47 mg/dL) towards the end of treatment. Melatonin itself and changes in energy balance promoted reductions in ovarian mass (20.2%) and estrous cycle remained extensive (26.7%), arresting at diestrus. Regarding the oxidative profile, lipid hydroperoxide levels decreased after melatonin treatment (6.9%) and total antioxidant substances were enhanced within the ovaries (23.9%). Additionally, melatonin increased superoxide dismutase (21.3%), catalase (23.6%) and glutathione-reductase (14.8%) activities and the reducing power (10.2% GSH/GSSG ratio). We suggest that melatonin alters ovarian mass and estrous cyclicity and protects the ovaries by increasing superoxide dismutase, catalase and glutathione-reductase activities.

Typical and atypical enteropathogenic Escherichia coli bacterial translocation associated with tissue hypoperfusion in rats

Although enteropathogenic Escherichia coli (EPEC) are well-recognized diarrheal agents, their ability to translocate and cause extraintestinal alterations is not known. We investigated whether a typical EPEC (tEPEC) and an atypical EPEC (aEPEC) strain translocate and cause microcirculation injury under conditions of intestinal bacterial overgrowth. Bacterial translocation (BT) was induced in female Wistar-EPM rats (200-250 g) by oroduodenal catheterization and inoculation of 10 mL 10(10) colony forming unit (CFU)/mL, with the bacteria being confined between the duodenum and ileum with ligatures. After 2 h, mesenteric lymph nodes (MLN), liver and spleen were cultured for translocated bacteria and BT-related microcirculation changes were monitored in mesenteric and abdominal organs by intravital microscopy and laser Doppler flow, respectively. tEPEC (N = 11) and aEPEC (N = 11) were recovered from MLN (100%), spleen (36.4 and 45.5%), and liver (45.5 and 72.7%) of the animals, respectively. Recovery of the positive control E. coli R-6 (N = 6) was 100% for all compartments. Bacteria were not recovered from extraintestinal sites of controls inoculated with non-pathogenic E. coli strains HB101 (N = 6) and HS (N = 10), or saline. Mesenteric microcirculation injuries were detected with both EPEC strains, but only aEPEC was similar to E. coli R-6 with regard to systemic tissue hypoperfusion. In conclusion, overgrowth of certain aEPEC strains may lead to BT and impairment of the microcirculation in systemic organs.

Glial cell activity is maintained during prolonged inflammatory challenge in rats

We evaluated the expression of glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), ionized calcium binding adaptor protein-1 (Iba-1), and ferritin in rats after single or repeated lipopolysaccharide (LPS) treatment, which is known to induce endotoxin tolerance and glial activation. Male Wistar rats (200-250 g) received ip injections of LPS (100 µg/kg) or saline for 6 days: 6 saline (N = 5), 5 saline + 1 LPS (N = 6) and 6 LPS (N = 6). After the sixth injection, the rats were perfused and the brains were collected for immunohistochemistry. After a single LPS dose, the number of GFAP-positive cells increased in the hypothalamic arcuate nucleus (ARC; 1 LPS: 35.6 ± 1.4 vs control: 23.1 ± 2.5) and hippocampus (1 LPS: 165.0 ± 3.0 vs control: 137.5 ± 2.5), and interestingly, 6 LPS injections further increased GFAP expression in these regions (ARC = 52.5 ± 4.3; hippocampus = 182.2 ± 4.1). We found a higher GS expression only in the hippocampus of the 6 LPS injections group (56.6 ± 0.8 vs 46.7 ± 1.9). Ferritin-positive cells increased similarly in the hippocampus of rats treated with a single (49.2 ± 1.7 vs 28.1 ± 1.9) or repeated (47.6 ± 1.1 vs 28.1 ± 1.9) LPS dose. Single LPS enhanced Iba-1 in the paraventricular nucleus (PVN: 92.8 ± 4.1 vs 65.2 ± 2.2) and hippocampus (99.4 ± 4.4 vs 73.8 ± 2.1), but had no effect in the retrochiasmatic nucleus (RCA) and ARC. Interestingly, 6 LPS increased the Iba-1 expression in these hypothalamic and hippocampal regions (RCA: 57.8 ± 4.6 vs 36.6 ± 2.2; ARC: 62.4 ± 6.0 vs 37.0 ± 2.2; PVN: 100.7 ± 4.4 vs 65.2 ± 2.2; hippocampus: 123.0 ± 3.8 vs 73.8 ± 2.1). The results suggest that repeated LPS treatment stimulates the expression of glial activation markers, protecting neuronal activity during prolonged inflammatory challenges.

Evidence for the involvement of peripheral β-adrenoceptors in delayed liquid gastric emptying induced by dipyrone, 4-aminoantipyrine, and antipyrine in rats

Dipyrone (Dp), 4-aminoantipyrine (AA), and antipyrine (At) delay liquid gastric emptying (GE) in rats. We evaluated adrenergic participation in this phenomenon in a study in male Wistar rats (250-300 g) pretreated subcutaneously with guanethidine (GUA), 100 mg·kg−1·day−1, or vehicle (V) for 2 days before experimental treatments. Other groups of animals were pretreated intravenously (iv) 15 min before treatment with V, prazosin (PRA; 1 mg/kg), yohimbine (YOH; 3 mg/kg), or propranolol (PRO; 4 mg/kg), or with intracerebroventricular (icv) administration of 25 µg PRO or V. The groups were treated iv with saline or with 240 µmol/kg Dp, AA, or At. GE was determined 10 min later by measuring the percentage of gastric retention (%GR) of saline labeled with phenol red 10 min after gavage. %GR (mean±SE, n=8) indicated that GUA abolished the effect of Dp (GUA vs V=31.7±1.6 vs47.1±2.3%) and of At (33.2±2.3 vs 54.7±3.6%) on GE and significantly reduced the effect of AA (48.1±3.2 vs67.2±3.1%). PRA and YOH did not modify the effect of the drugs. %GR (mean±SE, n=8) indicated that iv, but noticv, PRO abolished the effect of Dp (PROvs V=29.1±1.7 vs 46.9±2.7%) and At (30.5±1.7 vs 49±3.2%) and significantly reduced the effect of AA (48.4±2.6 vs 59.5±3.1%). These data suggest activation of peripheral β-adrenoceptors in the delayed GE induced by phenylpyrazolone derivatives.

Effects of eugenol on resting tension of rat atria

In cardiac and skeletal muscle, eugenol (μM range) blocks excitation-contraction coupling. In skeletal muscle, however, larger doses of eugenol (mM range) induce calcium release from the sarcoplasmic reticulum. The effects of eugenol are therefore dependent on its concentration. In this study, we evaluated the effects of eugenol on the contractility of isolated, quiescent atrial trabeculae from male Wistar rats (250-300 g; n=131) and measured atrial ATP content. Eugenol (1, 3, 5, 7, and 10 mM) increased resting tension in a dose-dependent manner. Ryanodine [100 µM; a specific ryanodine receptor (RyR) blocker] and procaine (30 mM; a nonspecific RyR blocker) did not block the increased resting tension induced by eugenol regardless of whether extracellular calcium was present. The myosin-specific inhibitor 2,3-butanedione monoxime (BDM), however, reversed the increase in resting tension induced by eugenol. In Triton-skinned atrial trabeculae, in which all membranes were solubilized, eugenol did not change resting tension, maximum force produced, or the force vs pCa relationship (pCa=-log [Ca2+]). Given that eugenol reduced ATP concentration, the increase in resting tension observed in this study may have resulted from cooperative activation of cardiac thin filaments by strongly attached cross-bridges (rigor state).

Avaliação de diferentes híbridos suínos submetidos à insensibilização elétrica e gasosa (CO2): parte 2 - mensurações objetivas de qualidade

Suínos provenientes de três linhagens genética (A, B e C) comercializados no Brasil, com peso vivo de 100 a 120 kg foram submetidos ao insensibilizador elétrico manual (Karl Schermer 220-230/250 volts, 45-60 Hz e 1,4-1,5A) e ao gasoso coletivo (Combi-Butina 90% CO2) no mesmo abatedouro. O sistema gasoso proporcionou aos híbridos valores (b*) superiores (p<0,001) quando comparados ao sistema elétrico, assim como diferenças nos valores médios de refletância luminosa interna (Hennessy-gp4) aos 45 min. pm e 24ª h pm (p<0,05). Quando submetidos ao sistema gasoso, diferenças entre os híbridos nos valores médios de luminosidade superficial (L) 24ª h pm (p<0,0001), pH 24ª h pm (SM) (p<0,0001), valores (b*) 24ª h pm (p<0,05), reflectância luminosa interna aos 45 min e 24ª h (LD) (p<0,001) foram observadas. Utilizando-se o sistema manual elétrico verificaram-se diferenças significativas nos valores médios de refletância luminosa interna (LD) aos 45 min. e 24ª h pm (p<0,001), assim como nos valores médios de pH 24ª h pm (SM) e (SC) (p<0,05). Entretanto as diferenças obtidas entre os sistemas de insensibilização e híbridos estudados não foram suficientes para proporcionar diferenças significativas nos valores de capacidade de retenção de água, perda por exsudação e "umidade exprimível".

Avaliação de diferentes híbridos suínos submetidos à insensibilização elétrica e gasosa (CO2). Parte 1: mensuração de indicadores sanguíneos de estresse

Suínos provenientes de três linhagens genéticas A, B e C comercializadas no Brasil, com peso vivo de 100 a 120 kg foram submetidos ao insensibilizador elétrico manual (Karl Schermer 220-230/250 volts, 45-60 Hz e 1,4 -1,5 A) e ao sistema gasoso coletivo (COMBI-BUTINA 90% CO2). Alíquotas sanguíneas, para determinação dos níveis de creatina fosfoquinase (CPK), lactato e cortisol, assim como amostras do músculo semimembranosus (10 g) para a determinação do gene halotano, foram coletadas. Comparando-se os sistemas de insensibilização elétrico e gasoso (CO2), o elétrico demonstrou ser mais estressante, proporcionando maiores concentrações plasmáticas de cortisol (p < 0,001) e lactato (p < 0,001) para as linhagens genéticas A e C, nas condições estudadas, porém não se observou diferenças significativas para os indicadores sanguíneos e sistemas de insensibilização em questão quando a linhagem B foi considerada. Diferenças significativas entre as linhagens genéticas A, B e C foram obtidas comparando-se os valores plasmáticos de creatina fosfoquinase (p < 0,001), lactato (p < 0,001) e cortisol (p < 0,001) quando atordoados com o sistema gasoso, entretanto, quando o sistema elétrico foi utilizado, somente os valores de cortisol apresentaram diferenças significativas (p < 0,001). A presença do gene halotano (Nn) foi observada somente na linhagem B.

Ocorrência de desoxinivalenol em trigo nacional e importado utilizado no Brasil

A fusariose, também conhecida como giberela é uma doença importante, causada principalmente pelo fungo Fusarium graminearum, que afeta de forma generalizada as regiões produtoras de trigo do Brasil e dos principais países do qual o produto é importado. Além dos danos diretos causados pela doença, os grãos infectados podem ser tóxicos para o homem e animais devido à presença de micotoxinas especialmente o desoxinivalenol (DON). A contaminação com DON foi avaliada em 100 amostras de trigo, sendo 50 de trigo nacional (provenientes dos Estados de São Paulo, Paraná e Rio Grande do Sul) e 50 de trigo importado (Argentina e Paraguai). As amostras foram coletadas durante o período de maio a dezembro de 2005 de empresas que normalmente comercializam ou processam trigo e foram analisadas por cromatografia em camada delgada. Os resultados indicaram que, do total de amostras avaliadas, 94% do trigo nacional e 88% do trigo importado apresentaram-se positivas quanto a presença de DON. Os níveis médios de contaminação com DON do trigo nacional (332 µg.kg- 1) foram maiores (p < 0,05) do que do trigo importado (90 µg.kg -1). Apenas 2 amostras (4%) do trigo nacional apresentaram níveis de contaminação maiores que 1.250 µg.kg -1, teor máximo aceitável pela Comunidade Européia.