Paradoxical increase of exploratory behavior in the elevated plus-maze by rats exposed to two kinds of aversive stimuli

Albino rats were submitted to a 24-h period of social isolation (individual housing) combined with 0, 1, 2 or 3 twenty-four-hour periods of exposure to different vivaria (novelty) and tested in the elevated plus-maze. Results, reported as mean ± SEM for N = 12, show that the time (in seconds) spent in the open arms by rats exposed to novelty for 0, 1, 2 and 3 days was 28.3 ± 4.4, 31.6 ± 3.2, 29.1 ± 3.5 and 25.0 ± 3.3, respectively, when grouped in the same vivarium; 29.6 ± 2.7, 7.6 ± 2.1, 9.6 ± 4.4 and 28.5 ± 3.7 when grouped in different vivaria; 2.9 ± 1.1, 1.8 ± 1.0, 2.7 ± 1.1 and 0 ± 0 when isolated in the same vivarium, and 2.6 ± 1.1, 31.5 ± 8.2, 24.8 ± 4.2 and 0 ± 0 when isolated in different vivaria. The number of entries into the open and closed arms followed a similar trend. This indicates that, separately, both exposure to novelty and isolation are aversive manipulations. Paradoxically, when novelty was combined with a concomitant 24-h period of social isolation prior to testing, the decrease in exploratory behavior caused by either of the two aversive manipulations alone was reverted. These results are indicative that less intense anxiety triggers mechanisms mediating less energetic behavior such as freezing, while higher levels trigger mechanisms mediating more vigorous action, such as flight/fight behavior, since the combination of two aversive situations resulted in more exploratory behavior than with either alone. They are also suggestive of habituation to the effects of novelty, since exposure to it for 3 days produced exploratory behavior similar to that of controls

The relationship between anxiety and depression in animal models: a study using the forced swimming test and elevated plus-maze

The present study evaluated the correlation between the behavior of mice in the forced swimming test (FST) and in the elevated plus-maze (PM). The effect of the order of the experiments, i.e., the influence of the first test (FST or PM) on mouse behavior in the second test (PM or FST, respectively) was compared to handled animals (HAND). The execution of FST one week before the plus-maze (FST-PM, N = 10), in comparison to mice that were only handled (HAND-PM, N = 10) in week 1, decreased % open entries (HAND-PM: 33.6 ± 2.9; FST-PM: 20.0 ± 3.9; mean ± SEM; P<0.02) and % open time (HAND-PM: 18.9 ± 3.3; FST-PM: 9.0 ± 1.9; P<0.03), suggesting an anxiogenic effect. No significant effect was seen in the number of closed arm entries (FST-PM: 9.5 (7.0-11.0); HAND-PM: 10.0 (4.0-14.5), median (interquartile range); U = 46.5; P>0.10). A prior test in the plus-maze (PM-FST) did not change % immobility time in the FST when compared to the HAND-FST group (HAND-FST: 57.7 ± 3.9; PM-FST: 65.7 ± 3.2; mean ± SEM; P>0.10). Since these data suggest that there is an order effect, the correlation was evaluated separately with each test sequence: FST-PM (N = 20) and PM-FST (N = 18). There was no significant correlation between % immobility time in the FST and plus-maze indexes (% time and entries in open arms) in any test sequence (r: -0.07 to 0.18). These data suggest that mouse behavior in the elevated plus-maze is not related to behavior in the forced swimming test and that a forced swimming test before the plus-maze has an anxiogenic effect even after a one-week interval.

Identification of hemolytic and neuroactive fractions in the venom of the sea anemone Bunodosoma cangicum

Sea anemones are a rich source of biologically active substances. In crayfish muscle fibers, Bunodosoma cangicum whole venom selectively blocks the I K(Ca) currents. In the present study, we report for the first time powerful hemolytic and neuroactive effects present in two different fractions obtained by gel-filtration chromatography from whole venom of B. cangicum. A cytolytic fraction (Bcg-2) with components of molecular mass ranging from 8 to 18 kDa elicited hemolysis of mouse erythrocytes with an EC50 = 14 µg/ml and a maximum dose of 22 µg/ml. The effects of the neuroactive fraction, Bcg-3 (2 to 5 kDa), were studied on isolated crab nerves. This fraction prolonged the compound action potentials by increasing their duration and rise time in a dose-dependent manner. This effect was evident after the washout of the preparation, suggesting the existence of a reversible substance that was initially masking the effects of an irreversible one. In order to elucidate the target of Bcg-3 action, the fraction was applied to a tetraethylammonium-pretreated preparation. An additional increase in action potential duration was observed, suggesting a blockade of a different population of K+ channels or of tetraethylammonium-insensitive channels. Also, tetrodotoxin could not block the action potentials in a Bcg-3-pretreated preparation, suggesting a possible interaction of Bcg-3 with Na+ channels. The present data suggest that B. cangicum venom contains at least two bioactive fractions whose activity on cell membranes seems to differ from the I K(Ca) blockade described previously.

Antinociceptive effects of the essential oil of Croton zehntneri in mice

Croton zehntneri is an aromatic plant native to Northeastern Brazil, where it is often used in folk medicine. In the present study the antinociceptive effects of the essential oil of Croton zehntneri (EOCz) were evaluated in mice. EOCz administered orally at doses of 100 and 300 mg/kg reduced paw licking time in the second phase of the formalin test from the control value of 41.61 ± 8.62 to 12.01 ± 7.97 and 6.57 ± 3.42 s, respectively. During the first phase of the formalin test only 300 mg/kg induced a significant alteration (from 58.2 ± 7.02, control, to 28.7 ± 4.73 s). The number of contortions in response to intraperitoneal injections of acetic acid did not differ significantly between controls (80.6 ± 9.01) and experimental (300 mg/kg body weight) animals (89.1 ± 9.53% of the control numbers; P > or = 0.05, Student t-test). In the hot-plate test, EOCz at doses > or = 100 mg/kg significantly increased the latency time with respect to controls (11.2 ± 0.80). At 100 and 300 mg/kg this increase persisted for 180 and 240 min, respectively. The data show that EOCz is effective as an antinociceptive agent.

Reproductive experience influences grooming behavior during pregnancy in rats

The pregnancy-induced increase in self-licking observed in rats is important for mammary gland development and lactation. Reproductive experience has epidemiologial implications such as a decrease in the incidence of mammary gland cancer in women and it also influences various behavioral, neurochemical and endocrine parameters. The aim of the present study was to investigate the influence of reproductive experience on grooming behavior patterns during pregnancy in rats. Self-grooming behavior was measured in age-matched virgin, primi- and multigravid (days 7, 8, 9, 19, and 20 of pregnancy) rats. General grooming (head, forelimbs and shoulders) was not significantly different among virgin, primi- and multigravid rats during pregnancy. Confirming previous work, pregnant rats spent significantly more time in specific grooming (mammary glands, nipple lines, genital and pelvic regions) than did virgin animals. In addition, self- licking of mammary glands was significantly increased in multi- as compared to primigravid rats on days 8, 9, 19 and 20 of pregnancy. The increase in mammary gland grooming observed in multigravid rats appears to be a consequence of previous reproductive experience. These data show that reproductive experience modulates mammary gland grooming during pregnancy, possibly contributing to successful reproduction.

Thalassemia intermedia as a result of heterozygosis for ß0-thalassemia and aaaanti-3.7/aa genotype in a Brazilian patient

We report a case in which the interaction of heterozygosis for both the ß0-IVS-II-1 (G->A) mutation and the aaaanti-3.7 allele was the probable cause for the clinical occurrence of thalassemia intermedia. The propositus, a 6-year-old Caucasian Brazilian boy of Portuguese descent, showed a moderately severe chronic anemia in spite of having the ß-thalassemia trait. Investigation of the alpha-globin gene status revealed heterozygosis for alpha-gene triplication (aaa/aa). The patient's father, also presenting mild microcytic and hypochromic anemia, had the same alpha and ß genotypes as his son, while the mother, not related to the father and hematologically normal, was also a carrier of the aaaanti-3.7 allele. The present case emphasizes the need for considering the possibility of alpha-gene triplication in ß-thalassemia heterozygotes who display an unexpected severe phenotype. The ß-thalassemia mutation found here is being described for the first time in Brazil.

Clinical and molecular analysis of human reproductive disorders in Brazilian patients

Several genes that influence the development and function of the hypothalamic-pituitary-gonadal-axis (HPG) have been identified. These genes encode an array of transcription factors, matrix proteins, hormones, receptors, and enzymes that are expressed at multiple levels of the HPG. We report the experience of a single Endocrinology Unit in the identification and characterization of naturally occurring mutations in families affected by HPG disorders, including forms of precocious puberty, hypogonadism and abnormal sexual development due to impaired gonadotropin function. Eight distinct genes implicated in HPG function were studied: KAL, SF1, DAX1, GnRH, GnRHR, FSHß, FSHR, and LHR. Most mutations identified in our cohort are described for the first time in literature. New mutations in SF1, DAX1 and GnRHR genes were identified in three Brazilian patients with hypogonadism. Eight boys with luteinizing hormone- (LH) independent precocious puberty due to testotoxicosis were studied, and all have their LH receptor (LHR) defects elucidated. Among the identified LHR molecular defects, three were new activating mutations. In addition, these mutations were frequently associated with new clinical and hormonal aspects, contributing significantly to the knowledge of the molecular basis of reproductive disorders. In conclusion, the naturally occurring genetic mutations described in the Brazilian families studied provide important insights into the regulation of the HPG.

Community-based transconjunctival marginal rotation for cicatricial trachoma in Indians from the Upper Rio Negro basin

The objective of the present study was to describe, for the first time in Brazil, the use by a non-ophthalmologist of a community-based marginal rotation procedure by a posterior approach in the indigenous population from the Upper Rio Negro basin. Seventy-three upper eyelids of 46 Indians (11 males and 35 females) with cicatricial upper eyelid entropion and trichiasis were operated in the Indian communities using a marginal rotational procedure by a posterior approach by a non-ophthalmologist physician who had general surgery experience but only an extremely short period (one week) of ophthalmic training. Subjects were reevaluated 6 months after surgery. Results were classified according to the presence and location of residual trichiasis and symptoms were assessed according to a three-level subjective scale (better, worse or no change). Fifty-six eyelids (76.7%) were free from trichiasis, whereas residual trichiasis was observed in 17 eyelids (23.3%) of 10 subjects. In these cases, trichiasis was either lateral or medial to the central portion of the lid. Of these 10 patients, only 4 reported that the surgery did not improve the irritative symptoms. We conclude that marginal rotation by a posterior approach is an effective and simple procedure with few complications, even when performed by non-specialists. Due to its simplicity the posterior approach is an excellent option for community-based upper eyelid entropion surgery.

Behavioral changes induced by cocaine in mice are modified by a hyperlipidic diet or recombinant leptin

The objective of the present study was to determine if the acute behavioral effects of cocaine acutely administered intraperitoneally (ip) at doses of 5, 10 and 20 mg/kg on white male CF1 mice, 90 days of age, would be influenced by leptin acutely administered ip (at doses of 5, 10 and 20 µg/kg) or by endogenous leptin production enhanced by a high-fat diet. The acute behavioral effects of cocaine were evaluated in open-field, elevated plus-maze and forced swimming tests. Results were compared between a group of 80 mice consuming a balanced diet and a high-fat diet, and a group of 80 mice fed a commercially available rodent chow formula (Ralston Purina) but receiving recombinant leptin (rLeptin) or saline ip. Both the high-fat-fed and rLeptin-treated mice showed decreased locomotion in the open-field test, spent more time in the open arms of the elevated plus-maze and showed less immobility time in the forced swimming test (F(1,68) = 7.834, P = 0.007). There was an interaction between diets and cocaine/saline treatments in locomotion (F(3,34) = 3.751, P = 0.020) and exploration (F(3,34) = 3.581, P = 0.024). These results suggest that anxiolytic effects and increased general activity were induced by leptin in cocaine-treated mice and that low leptin levels are associated with behavioral depression. Chronic changes in diet composition producing high leptin levels or rLeptin treatment may result in an altered response to cocaine in ethologic tests that measure degrees of anxiety and depression, which could be attributed to an antagonistic effect of leptin.

Sleep deprivation reduces the lymphocyte count in a non-obese mouse model of type 1 diabetes mellitus

The objective of the present study was to determine whether sleep deprivation (SD) would promote changes in lymphocyte numbers in a type 1 diabetes model (non-obese diabetic, NOD, mouse strain) and to determine whether SD would affect female and male NOD compared to Swiss mice. The number of lymphocytes in peripheral blood after 24 and 96 h of SD (by multiple platform method) or equivalent period of time in home-cage controls was examined prior to the onset of diabetes. SD for 96 h significantly reduced lymphocytes in male Swiss mice compared to control (8.6 ± 2.1 vs 4.1 ± 0.7 10³/µL; P < 0.02). In male NOD animals, 24- and 96-h SD caused a significant decrease of lymphocytes compared to control (4.4 ± 0.3 vs 1.6 ± 0.5; P < 0.001 and 4.4 ± 0.3 vs 0.9 ± 0.1 10³/µL; P < 0.00001, respectively). Both 24- and 96-h SD induced a reduction in the number of lymphocytes in female Swiss (7.5 ± 0.5 vs 4.5 ± 0.5, 4.4 ± 0.6 10³/µL; P < 0.001, respectively) and NOD mice (4 ± 0.6 vs 1.8 ± 0.2, 1.2 ± 0.4 10³/µL; P < 0.01, respectively) compared to the respective controls. Loss of sleep induced lymphopenia in peripheral blood in both genders and strains used. Since many cases of autoimmunity present reduced numbers of lymphocytes and, in this study, it was more evident in the NOD strain, our results suggest that SD should be considered a risk factor in the onset of autoimmune disorders.

Behavioral deficits in sepsis-surviving rats induced by cecal ligation and perforation

Sepsis and its complications are the leading causes of mortality in intensive care units, accounting for 10-50% of deaths. Intensive care unit survivors present long-term cognitive impairment, including alterations in memory, attention, concentration, and/or global loss of cognitive function. In the present study, we investigated behavioral alterations in sepsis-surviving rats. One hundred and ten male Wistar rats (3-4 months, 250-300 g) were submitted to cecal ligation and puncture (CLP), and 44 were submitted to sham operation. Forty-four rats (40%) survived after CLP, and all sham-operated animals survived and were used as control. Twenty animals of each group were used in the object recognition task (10 in short-term memory and 10 in long-term memory), 12 in the plus-maze test and 12 in the forced swimming test. Ten days after surgery, the animals were submitted individually to an object recognition task, plus-maze and forced swimming tests. A significant impairment of short- and long-term recognition memory was observed in the sepsis group (recognition index 0.75 vs 0.55 and 0.74 vs 0.51 for short- and long-term memory, respectively (P < 0.05). In the elevated plus-maze test no difference was observed between groups in any of the parameters assessed. In addition, sepsis survivors presented an increase in immobility time in the forced swimming test (180 vs 233 s, P < 0.05), suggesting the presence of depressive-like symptoms in these animals after recovery from sepsis. The present results demonstrated that rats surviving exposure to CLP, a classical sepsis model, presented recognition memory impairment and depressive-like symptoms but not anxiety-like behavior.

Gender and age differences in polysomnography findings and sleep complaints of patients referred to a sleep laboratory

Our objective was to examine the effet of gender on the sleep pattern of patients referred to a sleep laboratory. The data (questionnaires and polysomnographic recordings) were collected from a total of 2365 patients (1550 men and 815 women). The polysomnography permits an objective assessment of the sleep pattern. We included only polysomnography exams obtained with no more than one recording system in order to permit normalization of the data. Men had a significantly higher body mass index than women (28.5 ± 4.8 vs 27.7 ± 6.35 kg/m²) and had a significantly higher score on the Epworth Sleepiness Scale (10.8 ± 5.3 vs 9.5 ± 6.0), suggesting daytime sleepiness. Women had a significantly higher sleep latency than men, as well as a higher rapid eye movement (REM) latency. Men spent more time in stages 1 (4.6 ± 4.1 vs 3.9 ± 3.8) and 2 (57.0 ± 10.5 vs 55.2 ± 10.1) of non-REM sleep than women, whereas women spent significantly more time in deep sleep stages (3 and 4) than men (22.6 ± 9.0 vs 19.9 ± 9.0). The apnea/hypopnea and arousal indexes were significantly higher and more frequent in men than in women (31.0 ± 31.5 vs 17.3 ± 19.7). Also, periodic leg movement index did not differ significantly between genders, but rather differed among age groups. We did not find significant differences between genders in the percentage of REM sleep and sleep efficiency. The results of the current study suggest that there are specific gender differences in sleep pattern.

Tracheal instillation of urban PM2.5 suspension promotes acute cardiac polarization changes in rats

The mechanisms by which PM2.5 increases cardiovascular mortality are not fully identified. Autonomic alterations are the current main hypotheses. Our objective was to determine if PM2.5 induces acute cardiac polarization alterations in healthy Wistar rats. PM2.5 samples were collected on polycarbonate filters. Solutions containing 10, 20, and 50 µg PM2.5 were administered by tracheal instillation. P wave duration decreased significantly at 20 µg (0.99 ± 0.06, 0.95 ± 0.06, and 0.96 ± 0.07; P < 0.001), and 50 µg (0.98 ± 0.06, 0.98 ± 0.07, and 0.96 ± 0.08; 60, 90 and 120 min, respectively) compared to blank filter solution (P < 0.001). PR interval duration decreased significantly at 20 µg (0.99 ± 0.06, 0.98 ± 0.07, and 0.97 ± 0.08) and 50 µg (0.99 ± 0.05, 0.97 ± 0.0, and 0.95 ± 0.05; 60, 90, and 120 min, respectively) compared to blank filter and 10 µg (P < 0.001). QRS interval duration decreased at 20 and 50 µg in relation to blank filter solution and 10 µg (P < 0.001). QT interval duration decreased significantly (P < 0.001) with time in animals receiving 20 µg (0.94 ± 0.12, 0.88 ± 0.14, and 0.88 ± 0.11) and 50 µg (1.00 ± 0.13; 0.97 ± 0.11 and 0.98 ± 0.16; 60, 90 and 120 min, respectively) compared to blank filter solution and 10 µg (P < 0.001). PM2.5 induced reduced cardiac conduction time, within a short period, indicating that depolarization occurs more rapidly across ventricular tissue.

Antipyretic and antioxidant activities of 5-trifluoromethyl-4,5-dihydro-1H-pyrazoles in rats

The objective of this study was to determine the effect of eight 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-carboxyamidepyrazoles (TFDPs) on rat body temperature and baker’s yeast-induced fever. TFDPs or vehicle (5% Tween 80 in 0.9% NaCl, 5 mL/kg) were injected subcutaneously and rectal temperature was measured as a function of time in 28-day-old male Wistar rats (N = 5-12 per group). Antipyretic activity was determined in feverish animals injected with baker’s yeast (Saccharomyces cerevisiae suspension, 0.135 mg/kg, 10 mL/kg, ip). 3-Ethyl- and 3-propyl-TFDP (140 and 200 μmol/kg, respectively, 4 h after yeast injection) attenuated baker’s yeast-induced fever by 61 and 82%, respectively. These two effective antipyretics were selected for subsequent analysis of putative mechanisms of action. We then determined the effects on cyclooxygenase-1 and -2 (COX-1 and COX-2) activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) oxidation in vitro, on tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels and on leukocyte counts in the washes of peritoneal cavities of rats injected with baker’s yeast. While 3-ethyl- and 3-propyl-TFDP did not reduce baker’s yeast-induced increases of IL-1β or TNF-α levels, 3-ethyl-TFDP caused a 42% reduction in peritoneal leukocyte count. 3-Ethyl- and 3-propyl-TFDP did not alter COX-1 or COX-2 activities in vitro, but presented antioxidant activity in the DPPH assay with an IC50 of 39 mM (25-62) and 163 mM (136-196), respectively. The data indicate that mechanisms of action of these two novel antipyretic pyrazole derivatives do not involve the classic inhibition of the COX pathway or pyrogenic cytokine release.

Morphometric analysis of the phrenic nerve in male and female Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR)

Ventilatory differences between rat strains and genders have been described but the morphology of the phrenic nerve has not been investigated in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. A descriptive and morphometric study of the phrenic nerves of male (N = 8) and female (N = 9) SHR, and male (N = 5) and female (N = 6) WKY is presented. After arterial pressure and heart rate recordings, the phrenic nerves of 20-week-old animals were prepared for epoxy resin embedding and light microscopy. Morphometric analysis performed with the aid of computer software that took into consideration the fascicle area and diameter, as well as myelinated fiber profile and Schwann cell nucleus number per area. Phrenic nerves were generally larger in males than in females on both strains but larger in WKY compared to SHR for both genders. Myelinated fiber numbers (male SHR = 228 ± 13; female SHR = 258 ± 4; male WKY = 382 ± 23; female WKY = 442 ± 11 for proximal right segments) and density (N/mm²; male SHR = 7048 ± 537; female SHR = 10355 ± 359; male WKY = 9457 ± 1437; female WKY = 14351 ± 1448) for proximal right segments) were significantly larger in females of both groups and remarkably larger in WKY than SHR for both genders. Strain and gender differences in phrenic nerve myelinated fiber number are described for the first time in this experimental model of hypertension, indicating the need for thorough functional studies of this nerve in male and female SHR.