Effect of one-week ethanol treatment on monoamine levels and dopaminergic receptors in rat striatum

We studied the effects of ethanol on the levels of norepinephrine, dopamine, serotonin (5-HT) and their metabolites as well as on D1- and D2-like receptors in the rat striatum. Ethanol (2 or 4 g/kg, po) was administered daily by gavage to male Wistar rats and on the 7th day, 30 min or 48 h after drug administration, the striatum was dissected for biochemical assays. Monoamine and metabolite concentrations were measured by HPLC and D1- and D2-like receptor densities were determined by binding assays. Scatchard analyses showed decreases of 30 and 43%, respectively, in D1- and D2-like receptor densities and no change in dissociation constants (Kd) 48 h after the withdrawal of the dose of 4 g/kg. Ethanol, 2 g/kg, was effective only on the density of D2-like receptors but not on Kd of either receptor. Thirty minutes after the last ethanol injection (4 g/kg), decreases of D2 receptor density (45%) as well as of Kd values (34%) were detected. However, there was no significant effect on D1-like receptor density and a 46% decrease was observed in Kd. An increase in dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC), a decrease in norepinephrine, and no alteration in 5-HT levels were demonstrated after 48-h withdrawal of 4 g/kg ethanol. Similar effects were observed in dopamine and DOPAC levels 30 min after drug administration. No alteration in norepinephrine concentration and a decrease in 5-HT levels were seen 30 min after ethanol (4 g/kg) administration. Our findings indicate the involvement of the monoaminergic system in the responses to ethanol.

The modulatory effect of estradiol benzoate on superoxide dismutase activity in the developing rat brain

The sensitivity of copper,zinc (CuZn)- and manganese (Mn)-superoxide dismutase (SOD) to exogenous estradiol benzoate (EB) was investigated in Wistar rats during postnatal brain development. Enzyme activities were measured in samples prepared from brains of rats of both sexes and various ages between 0 and 75 days, treated sc with 0.5 µg EB/100 g body weight in 0.1 ml olive oil/100 g body weight, 48 and 24 h before sacrifice. In females, EB treatment stimulated MnSOD activity on days 0 (66.1%), 8 (72.7%) and 15 (81.7%). In males, the stimulatory effect of EB on MnSOD activity on day 0 (113.6%) disappeared on day 8 and on days 15 and 45 it became inhibitory (40.3 and 30.5%, respectively). EB had no effect on the other age groups. The stimulatory effect of EB on CuZnSOD activity in newborn females (51.8%) changed to an inhibitory effect on day 8 (38.4%) and disappeared by day 45 when inhibition was detected again (48.7%). In males, the inhibitory effect on this enzyme was observed on days 0 (45.0%) and 15 (28.9%), and then disappeared until day 60 when a stimulatory effect was observed (38.4%). EB treatment had no effect on the other age groups. The sensitivity of MnSOD to estradiol differed significantly between sexes during the neonatal and prepubertal period, whereas it followed a similar pattern thereafter. The sensitivity of CuZnSOD to estradiol differed significantly between sexes during most of the study period. Regression analysis showed that the sensitivity of MnSOD to this estrogen tended to decrease similarly in both sexes, whereas the sensitivity of CuZnSOD showed a significantly different opposite tendency in female and male rats. These are the first reports indicating hormonal modulation of antioxidant enzyme activities related to the developmental process.

Dietary cellulose has no effect on the regeneration of hemoglobin in growing rats with iron deficiency anemia

The objective of the present study was to determine the effect of cellulose on intestinal iron absorption in rats during recovery from iron deficiency anemia. Twenty-one-day-old male Wistar-EPM rats were fed an iron-free ration for two weeks to induce anemia. At 5 weeks of age, the rats were divided into two groups (both groups receiving 35 mg of elemental iron per kg diet): cellulose group (N = 12), receiving a diet containing 100 g of cellulose/kg and control (N = 12), receiving a diet containing no cellulose. The fresh weight of the feces collected over a 3-day period between the 15th and 18th day of dietary treatment was 10.7 ± 3.5 g in the group receiving cellulose and 1.9 ± 1.2 g in the control group (P<0.001). Total food intake was higher in the cellulose group (343.4 ± 22.0 g) than in the control (322.1 ± 13.1 g, P = 0.009) during the 3 weeks of dietary treatment. No significant difference was observed in weight gain (cellulose group = 132.8 ± 19.2, control = 128.0 ± 16.3 g), hemoglobin increment (cellulose group = 8.0 ± 0.8, control = 8.0 ± 1.0 g/dl), hemoglobin level (cellulose group = 12.3 ± 1.2, control = 12.1 ± 1.3 g/dl) or in hepatic iron levels (cellulose group = 333.6 ± 112.4, control = 398.4 ± 168.0 µg/g dry tissue). We conclude that cellulose does not adversely affect the regeneration of hemoglobin, hepatic iron level or the growth of rats during recovery from iron deficiency anemia.

Antagonism of the acute hemodynamic effects of captopril in decompensated congestive heart failure by aspirin administration

The concomitant use of angiotensin-converting enzyme inhibitors and aspirin may cause pharmacological antagonism. Hence we examined the effect of aspirin on the neurohormonal function and hemodynamic response to captopril in heart failure patients. Between April 1999 and August 2000, 40 patients were randomized into four equal groups: 1) captopril, 2) aspirin, 3) captopril-aspirin: captopril was given alone on the first day, followed by aspirin on the remaining days, and 4) aspirin-captopril: aspirin was given alone on the first day, followed by captopril on the remaining days. Hemodynamic, norepinephrine and prostaglandin measurements were performed pre- and post-medication for 4 days. Captopril (50 mg) was given orally every 8 h and 300 mg aspirin was given on the first day, and 100 mg/day thereafter. In the captopril group and only on the first day of captopril-aspirin, captopril produced increases in cardiac index (2.1 ± 0.6 to 2.5 ± 0.5 l min-1 m-2, P<0.0001), and reduced peripheral vascular resistance (1980 ± 580 to 1545 ± 506 dyn s-1 cm-5/m², P<0.0001) and pulmonary wedge pressure (20 ± 4 to 15 ± 4 mmHg, P<0.0001). In contrast, aspirin alone or associated with captopril showed no significant hemodynamic changes. Norepinephrine decreased (P<0.02) only in the captopril group. Prostaglandin levels did not differ significantly among groups. Thus, aspirin compromises the short-term hemodynamic and neurohormonal effects of captopril in patients with acute decompensated heart failure.

Effect of cyproterone acetate on alpha1-adrenoceptor subtypes in rat vas deferens

Gonadal hormones regulate the expression of alpha1-adrenoceptor subtypes in several tissues. The present study was carried out to determine whether or not cyproterone acetate, an anti-androgenic agent, regulates the alpha1-adrenoceptor subtypes that mediate contractions of the rat vas deferens in response to noradrenaline. The actions of subtype selective alpha1-antagonists were investigated in vas deferens from control and cyproterone acetate-treated rats (10 mg/day, sc, for 7 days). Prazosin (pA2 ~9.5), phentolamine (pA2 ~8.3) and yohimbine (pA2 ~6.7) presented competitive antagonism consistent with activation of alpha1-adrenoceptors in vas deferens from both control and treated rats. The pA2 values estimated for WB 4101 (~9.5), benoxathian (~9.7), 5-methylurapidil (~8.5), indoramin (~8.7) and BMY 7378 (~6.8) indicate that alpha1A-adrenoceptors are involved in the contractions of the vas deferens from control and cyproterone acetate-treated rats. Treatment of the vas deferens from control rats with the alpha1B/alpha1D-adrenoceptor alkylating agent chloroethylclonidine had no effect on noradrenaline contractions, supporting the involvement of the alpha1A-subtype. However, this agent partially inhibited the contractions of vas deferens from cyproterone acetate-treated rats, suggesting involvement of multiple receptor subtypes. To further investigate this, the actions of WB 4101 and chloroethylclonidine were reevaluated in the vas deferens from rats treated with cyproterone acetate for 14 days. In these organs WB 4101 presented complex antagonism characterized by a Schild plot with a slope different from unity (0.65 ± 0.05). After treatment with chloroethylclonidine, the complex antagonism presented by WB 4101 was converted into classical competitive antagonism, consistent with participation of alpha1A-adrenoceptors as well as alpha1B-adrenoceptors. These results suggest that cyproterone acetate induces plasticity in the alpha1-adrenoceptor subtypes involved in the contractions of the vas deferens.

Effect of the establishment of dominance relationships on cortisol and other metabolic parameters in Nile tilapia (Oreochromis niloticus)

The objective of the present study was to investigate the influence of the establishment of dominance relationships and social stress on plasma cortisol and metabolite levels in Nile tilapia (Oreochromis niloticus). During the 30-day experiment, the fish weighing 236 ± 29 g were kept in individual aquaria, except for two pairings lasting 6 h each. Blood samples were taken from the animals before and after pairing. Display, approach, attack, rebuff, chase flight, and coloration were carried out on days 16 and 30. Activities and behaviors characteristic of the establishment of dominance relationships were described. It was possible to classify all experimental fish (N = 30) as dominant or subordinate. No differences were detected between dominant (N = 15) and subordinate (N = 15) fish during isolation or after pairing in cortisol (isolated: 5.76 ± 0.98 vs 5.42 ± 0.63; paired: 10.94 ± 1.62 vs 11.21 ± 2.45 µg/dl), glucose (isolated: 60.02 ± 4.9 vs 67.85 ± 16.16; paired: 110.44 ± 15.72 vs 136.26 ± 22.46 mg/dl), triglyceride (isolated: 167.87 ± 5.06 vs 185.68 ± 7.24; paired: 210.85 ± 13.40 vs 221.82 ± 12.70 mg/dl) or total protein levels (isolated: 7.01 ± 0.42 vs 6.69 ± 0.59; paired: 9.21 ± 0.62 vs 9.51 ± 0.66 g/dl). However, when isolated (N = 30) and paired (N = 30) tilapia were compared, there were significant differences in cortisol and metabolite levels. The similar response presented by dominant and subordinate tilapia indicates that establishment of dominance relationships was a stressor for both groups.

Effect of an aqueous extract of Scoparia dulcis on blood glucose, plasma insulin and some polyol pathway enzymes in experimental rat diabetes

The effects of an aqueous extract of the plant Scoparia dulcis (200 mg/kg) on the polyol pathway and lipid peroxidation were examined in the liver of streptozotocin adult diabetic male albino Wistar rats. The diabetic control rats (N = 6) presented a significant increase in blood glucose, sorbitol dehydrogenase, glycosylated hemoglobin and lipid peroxidation markers such as thiobarbituric acid reactive substances (TBARS) and hydroperoxides, and a significant decrease in plasma insulin and antioxidant enzymes such as glutathione peroxidase (GPx), glutathione-S-transferase (GST) and reduced glutathione (GSH) compared to normal rats (N = 6). Scoparia dulcis plant extract (SPEt, 200 mg kg-1 day-1) and glibenclamide (600 µg kg-1 day-1), a reference drug, were administered by gavage for 6 weeks to diabetic rats (N = 6 for each group) and significantly reduced blood glucose, sorbitol dehydrogenase, glycosylated hemoglobin, TBARS, and hydroperoxides, and significantly increased plasma insulin, GPx, GST and GSH activities in liver. The effect of the SPEt was compared with that of glibenclamide. The effect of the extract may have been due to the decreased influx of glucose into the polyol pathway leading to increased activities of antioxidant enzymes and plasma insulin and decreased activity of sorbitol dehydrogenase. These results indicate that the SPEt was effective in attenuating hyperglycemia in rats and their susceptibility to oxygen free radicals.

Effect of strenuous maternal exercise before and during pregnancy on rat progeny renal function

The effects of strenuous exercise before and during pregnancy on the renal function and morphological alterations of the progeny were determined in a study on female Wistar rats. This research was done based on a previous study carried out in our laboratory, which showed morphological alterations in rats submitted to this kind of exercise. As the form is related to the function, the physiological relevance of submitting a pregnant female to a high-intensity exercise training regimen could be explained by the fact that morphological alterations can influence kidney function. The animals were assigned to one of two groups: control animals that did not exercise during pregnancy and trained animals that swam for 120 min 5 days a week for 8 weeks before pregnancy and daily for 60 min over a period of 8 weeks starting on the second day of pregnancy. Seven rats of each group were analyzed for morphological alterations and for renal function. The progeny of the rats used for morphological evaluation were born by cesarean section and the progeny of the animals used to evaluate renal function were born normally. The progeny were two months old when renal function was evaluated. Fertility and morbidity were the same for both groups. Strenuous maternal exercise had no significant influence on glomerular filtration rate (GFR) but renal plasma flow was lower in the progeny of the trained group (mean ± SD, 16.65 ± 3.77 ml min-1 kg-1) compared to the progeny of the control group (33.42 ± 2.56 ml min-1 kg-1). Antidiuretic and antinatriuretic effects on the progeny of the trained group were observed, since urine flow as percentage of GFR and the fraction of urinary sodium excretion were lower in this group (1.38 ± 0.10 and 0.60 ± 0.04%, respectively) compared to the progeny of the control group (2.36 ± 0.11 and 1.55 ± 0.20%, respectively). Moreover, in this exercise program, fetuses from trained animals were small-sized (2.45 ± 0.19 vs 4.66 ± 2.45 g for control animals) and showed lower differentiation compared to fetuses from the control group. These effects were probably caused by caloric restriction, hypoxia and reduction of umbilical cord length.

Effect of the Escherichia coli EMO strain on experimental infection by Salmonella enterica serovar Typhimurium in gnotobiotic mice

An experimental infection with Salmonella enterica subsp. enterica serovar Typhimurium was evaluated in gnotobiotic mice previously exposed to a plasmid-free non-pathogenic Escherichia coli (EMO strain). Mice were exposed to EMO (experimental) or not (control) 10 days before challenge with Salmonella Typhimurium (10² colony forming units (CFU)/mouse). Survival after challenge was higher (P < 0.05) in the experimental group (16%) than in the control animals (0%). Histopathological examination of the colon and ileum mucosa of the experimental group showed less extensive lesions such as edema, cell inflammatory infiltration and hyperemia. The epithelial cells of the mucosal surface and the production of the mucous layer were also better preserved in the experimental group. The population levels of Salmonella Typhimurium in the feces were initially 10-fold lower (P < 0.05) in the experimental groups. However, 3 days after challenge both experimental and control groups showed similar population levels ranging from 10(8) to()10(9) CFU/g of feces. The intestinal contents of total and anti-Salmonella Typhimurium sIgA were higher in the experimental groups 10 days after inoculation of E. coli EMO strain. Translocation of Salmonella Typhimurium to the spleen was 10-fold lower (P < 0.05) in the experimental group only on day 3 after infection. This was not related to an increase in the bacterial blood clearance of the animals, as shown by experimental venous challenge with E. coli B41. In conclusion, treatment of mice with E. coli EMO strain promoted a relative protection against experimental infection with Salmonella Typhimurium. This protection was not due to the reduction of the population of pathogens in the intestine but was probably related to stimulation of the immune response.

Looking for the GAP effect in manual responses and the role of contextual influences in reaction time experiments

When the offset of a visual stimulus (GAP condition) precedes the onset of a target, saccadic reaction times are reduced in relation to the condition with no offset (overlap condition) - the GAP effect. However, the existence of the GAP effect for manual responses is still controversial. In two experiments using both simple (Experiment 1, N = 18) and choice key-press procedures (Experiment 2, N = 12), we looked for the GAP effect in manual responses and investigated possible contextual influences on it. Participants were asked to respond to the imperative stimulus that would occur under different experimental contexts, created by varying the array of warning-stimulus intervals (0, 300 and 1000 ms) and conditions (GAP and overlap): i) intervals and conditions were randomized throughout the experiment; ii) conditions were run in different blocks and intervals were randomized; iii) intervals were run in different blocks and conditions were randomized. Our data showed that no GAP effect was obtained for any manipulation. The predictability of stimulus occurrence produced the strongest influence on response latencies. In Experiment 1, simple manual responses were shorter when the intervals were blocked (247 ms, P < 0.001) in relation to the other two contexts (274 and 279 ms). Despite the use of choice key-press procedures, Experiment 2 produced a similar pattern of results. A discussion addressing the critical conditions to obtain the GAP effect for distinct motor responses is presented. In short, our data stress the relevance of the temporal allocation of attention for behavioral performance.

Effect of hyperbaric oxygenation on the regeneration of the liver after partial hepatectomy in rats

The aim of the present study was to assess the influence of hyperbaric oxygenation (HBO) on rat liver regeneration before and after partial hepatectomy. Rats were sacrificed 54 h after 15% hepatectomy, liver and body weights were measured, and serum alanine transaminase (ALT) and aspartate transaminase (AST) activity and albumin levels were determined. The lipid peroxide level, as indicated by malondialdehyde production in the remnant liver was measured, and liver sections were analyzed by light microscopy. Five groups of 10 rats in each group were studied. The preHBO and pre-hyperbaric pressure (preHB) groups were treated before partial hepatectomy with 100% O2 and 21% O2, respectively, at 202,650 pascals, daily for 3 days (45 min/day). The control group was not treated before partial hepatectomy and recovered under normal ambient conditions after the procedure. Groups postHBO and postHB were treated after partial hepatectomy with HBO and HB, respectively, three times (45 min/day). The preHBO group presented a significant increase in the initiation of the regeneration process of the liver 54 h postoperatively. The liver/body weight ratio was 0.0618 ± 0.0084 in the preHBO compared to 0.0517 ± 0016 g/g in the control animals (P = 0.016). In addition, the preHBO group showed significant better liver function (evaluated by the lowest serum ALT and AST activities, P = 0.002 and P = 0.008, respectively) and showed a significant decrease in serum albumin levels compared to control (P < 0.001). Liver lipid peroxide concentration was lowest in the preHBO group (P < 0.001 vs control and postHBO group) and light microscopy revealed that the composition of liver lobules in the preHBO group was the closest to normal histological features. These results suggest that HBO pretreatment was beneficial for rat liver regeneration after partial hepatectomy.

Effect of chronic fish oil supplementation on renal function of normal and cachectic rats

In the present study we determined the effect of chronic diet supplementation with n-3 PUFA on renal function of healthy and cachectic subjects by providing fish oil (1 g/kg body weight) to female rats throughout pregnancy and lactation and then to their offspring post-weaning and examined its effect on renal function parameters during their adulthood. The animals were divided into four groups of 5-10 rats in each group: control, control supplemented with fish oil (P), cachectic Walker 256 tumor-bearing (W), and W supplemented with fish oil (WP). Food intake was significantly lower in the W group compared to control (12.66 ± 4.24 vs 25.30 ± 1.07 g/day). Treatment with fish oil significantly reversed this reduction (22.70 ± 2.94 g/day). Tumor growth rate was markedly reduced in the P group (16.41 ± 2.09 for WP vs 24.06 ± 2.64 g for W). WP group showed a significant increase in mean glomerular filtration rate compared to P and control (1.520 ± 0.214 ml min-1 kg body weight-1; P < 0.05). Tumor-bearing groups had low urine osmolality compared to control rats. The fractional sodium excretion decreased in the W group compared to control (0.43 ± 0.16 vs 2.99 ± 0.87%; P < 0.05), and partially recovered in the WP group (0.90 ± 0.20%). In summary, the chronic supplementation with fish oil used in this study increased the amount of fat in the diet by only 0.1%, but caused remarkable changes in tumor growth rate and cachexia, also showing a renoprotective function.

One-year follow-up of the effects of sildenafil on pulmonary arterial hypertension and veno-occlusive disease

We hypothesized that chronic oral administration of the phosphodiesterase-5 inhibitor sildenafil could improve the exercise capacity and pulmonary hemodynamics in patients with pulmonary arterial hypertension (PAH) on the basis of previous short-term studies. We tested this hypothesis in 14 subjects with PAH, including seven patients with the idiopathic form and seven patients with atrial septal defects, but no other congenital heart abnormalities. Patients were subjected to a 6-min walk test and dyspnea was graded according to the Borg scale. Pulmonary flow and pressures were measured by Doppler echocardiography. Patients were given sildenafil, 75 mg orally three times a day, and followed up for 1 year. Sildenafil therapy resulted in the following changes: increase in the 6-min walk distance from a median value of 387 m (range 0 to 484 m) to 462 m (range 408 to 588 m; P < 0.01), improvement of the Borg dyspnea score from 4.0 (median value) to 3.0 (P < 0.01), and increased pulmonary flow (velocity-time integral) from a median value of 0.12 (range 0.08 to 0.25) to 0.23 (range 0.11 to 0.40; P < 0.01) with no changes in pulmonary pressures. In one patient with pulmonary veno-occlusive disease diagnosed by a lung biopsy, sildenafil had a better effect on the pulmonary wedge pressure than inhaled nitric oxide (15 and 29 mmHg, respectively, acute test). He walked 112 m at baseline and 408 m at one year. One patient died at 11 months of treatment. No other relevant events occurred. Thus, chronic administration of sildenafil improves the physical capacity of PAH patients and may be beneficial in selected cases of veno-occlusive disease.

Effect of air pollution on pediatric respiratory emergency room visits and hospital admissions

In order to assess the effect of air pollution on pediatric respiratory morbidity, we carried out a time series study using daily levels of PM10, SO2, NO2, ozone, and CO and daily numbers of pediatric respiratory emergency room visits and hospital admissions at the Children's Institute of the University of São Paulo Medical School, from August 1996 to August 1997. In this period there were 43,635 hospital emergency room visits, 4534 of which were due to lower respiratory tract disease. The total number of hospital admissions was 6785, 1021 of which were due to lower respiratory tract infectious and/or obstructive diseases. The three health end-points under investigation were the daily number of emergency room visits due to lower respiratory tract diseases, hospital admissions due to pneumonia, and hospital admissions due to asthma or bronchiolitis. Generalized additive Poisson regression models were fitted, controlling for smooth functions of time, temperature and humidity, and an indicator of weekdays. NO2 was positively associated with all outcomes. Interquartile range increases (65.04 µg/m³) in NO2 moving averages were associated with an 18.4% increase (95% confidence interval, 95% CI = 12.5-24.3) in emergency room visits due to lower respiratory tract diseases (4-day moving average), a 17.6% increase (95% CI = 3.3-32.7) in hospital admissions due to pneumonia or bronchopneumonia (3-day moving average), and a 31.4% increase (95% CI = 7.2-55.7) in hospital admissions due to asthma or bronchiolitis (2-day moving average). The study showed that air pollution considerably affects children's respiratory morbidity, deserving attention from the health authorities.

Preclinical evaluation of the antidiabetic effect of Eugenia jambolana seed powder in streptozotocin-diabetic rats

The world is facing an explosive increase in the incidence of diabetes mellitus and cost-effective complementary therapies are needed. The effects of Eugenia jambolana, a household remedy for diabetes, were studied. Streptozotocin diabetic female albino Wistar rats weighing 150-200 g (N = 6) were fed E. jambolana seed powder (250, 500 or 1000 mg/kg) for 15 days. Diabetic rats fed 500 and 1000 mg/kg seed powder showed an increase in body weight on day 20 in relation to day 5 (6 ± 4.7, 9 ± 7.8 vs diabetic control -16 ± 7.1 g, P < 0.001), a decrease in fasting blood glucose (75 ± 11.9, 123 ± 14.4 vs diabetic control -34 ± 12.1 mg/dl, P < 0.001), a difference in post-treatment fasting and peak blood glucose (38 ± 11.9, 36 ± 14.2 vs diabetic control 78 ± 11.9 mg/dl, P < 0.001), and a difference in liver glycogen (50 ± 6.8, 52 ± 7.5 vs normal control 90 ± 6.6 µg/g of liver tissue, P < 0.001). Tri-terpenoids, tannins, gallic acid, and oxalic acid were the chemical constituents detected in E. jambolana seed. The best results were obtained with an oral dose of 500 mg/kg. Subacute toxicity studies with a single administration of 2.5 and 5.0 g/kg seed powder showed no mortality or abnormality. These data on the antidiabetic effect of E. jambolana seed are adequate for approval of phase 2 clinical trials to evaluate this seed powder as complementary therapy in type 2 and type 1 diabetes.