Behavioural alterations provoked by prolonged calcitonin administration in rats

Present work investigated the effect of prolonged administration of salmon calcitonin, a hormone secreted by parafollicular cells from thyroid, on behavioural parameters of rats. Animals received calcitonin sc, 100 mUI/100 g of body weight, three times a week, during 50 days. Behaviour was assessed utilizing an Open Field, Elevated Plus-Maze and Hole Board apparatus. Calcitonin treatment in rats seems to modify open field and elevated plus maze behaviour, suggesting emotionality and anxiety state alterations of the animals. These conditions can be provoked due to the direct calcitonin action on its receptors, even though we do not exclude an action mediated by tissue calcium level alterations.

Chronic administration of risperidone in a rat model of schizophrenia: A behavioural, morphological and molecular study

In the present work we analyzed the effect of the chronic administration of risperidone (2mg/kg over 65 days) on behavioural, morphological and molecular aspects in an experimental model of schizophrenia obtained by bilateral injection of ibotenic acid into the ventral hippocampus of new-born rats. Our results show that during their adult lives the animals with hippocampal lesions exhibit different alterations, mainly at behavioural level and in the gene expression of dopamine D2 and 5-HT2A receptors. However, at morphological level the study performed on the prefrontal cortex did not reveal any alterations in either the thickness or the number of cells immunoreactive for c-Fos, GFAP, CBP or PV. Overall, risperidone administration elicited a trend towards the recovery of the values previously altered by the hippocampal lesion, approaching the values seen in the animals without lesions. It may be concluded that the administration of risperidone in the schizophrenia model employed helps to improve the altered functions, with no significant negative effects. © 2013.

Preliminary study on age- and sex-dependent alterations in the composition of skeletal muscle fibers of Brasileiro de Hipismo horses

The aim of this work was to characterize the distribution of myofibers in the gluteus medius muscle of inactive horses of the Brasileiro de Hipismo (BH) breed at different ages by means of histochemical analyses, according to sex and depth of the biopsy. A total of 78 inactive horses (9 castrated males, 35 stallions, and 34 females) of the BH breed, aged 1 to 4 years, were used. A percutaneous muscle biopsy was obtained with a 6.0-mm Bergstrom-type needle, which allowed the removal of muscle fragments at depths of 20 and 60 mm. Myofiber types were determined based on myofibrillar adenosine triphosphatase (mATPase) and nicotinamide dinucleotide tetrazolium reductase (NADH-TR) techniques. Morphometry of the fibers was determined based on cross-sectional area (CSA), mean frequency (F), and relative cross-sectional area (RCSA). The current study demonstrated that BH horses 3 and 4 years of age show a greater percentage of, and area occupied by, type IIA fibers and lower percentage of type IIX fibers in the gluteus medius muscle compared with horses 1 and 2 years of age. No difference was found between sexes in the frequency of and area occupied by the different fiber types at any of the depths and ages studied. In this study, females showed a greater CSA for all fibers in comparison with males, at 1 year of age. The results of the current study indicate that the gluteus medius muscle of inactive BH horses shows modifications in its structural and biochemical composition during the growth of the animals, leading to a better oxidative capacity.

Alterations in muscular enzymes of horses competing long-distance endurance rides under tropical climate

Estudaram-se as alterações de atividade das enzimas musculares creatino quinase (CK), lactato desidrogenase (LDH) e aspartato aminotransferase (AST) em um grupo de cavalos que utilizados em provas de enduro de 70 e 100km de distância, em cinco competições. Os valores (U/l) basais (antes da largada) foram 245,13±9,84 para CK, 496,61±14,76 para LDH e 328,95±8,65 para AST. Todas as atividades das enzimas decresceram no primeiro momento das provas (~30km). Valores de pico, significativamente diferentes, foram alcançados para CK (413,59±50,75) imediatamente após 70km de distância; 24 horas após para LDH (628,61±33,30); e 48 horas após as provas para AST (389,89±16,96). A monitoração do período de recuperação revelou diferente comportamento entre as concentrações enzimáticas com CK retornando aos valores basais 24 horas pós-provas (279,61 ± 23,05). LDH e AST retornaram aos valores basais, 72 horas pós-provas (505,25±33,78 e 359,35±24,90, respectivamente). Os dados obtidos revelaram diferentes alterações na concentração de enzimas musculares de cavalos de enduro, diretamente relacionadas com a duração do esforço.

Chromatin and morphometry alterations of bovine sperm head after Percoll (TM) density gradient centrifugation

The aim of this work was to assess the morphometry and chromatin integrity of bovine sperm head after a three layers discontinuous Percoll (TM) density gradient centrifugation. Frozen semen doses were obtained from six bulls of different breeds, including three taurine and three Zebu animals. Three ejaculates per bull were evaluated. The semen doses were thawed and two smears were made from each sample before (control) and after the Percoll (TM) centrifugation (Percoll (TM) group). The smears were stained with toluidine blue and grayscale digital images were captured and processed in Scilab environment software. It was observed that chromatin heterogeneity was reduced (P<0.05) and chromatin decondensation was increased (P<0.05) after the Percollm treatment utilized. In addition, it was observed that sperm head length was higher (P<0.05) and the side symmetry was lower (P<0.05) in centrifuged sperm cells. When analyzed separately by subspecies, it was observed that the decrease (P<0.05) in chromatin heterogeneity and the increase (P<0.05) in chromatin decondensation occurred in Zebu sperm heads. In addition, the length and the width:length ratio of sperm heads was affected by Percoll (TM) centrifugation in Zebu semen. In conclusion, the three layers discontinuous Percoll (TM) centrifugation increased the chromatin decondensation and the morphometric alterations of frozen-thawed bovine semen. However, the real implication of these findings in fertility rates of centrifuged sperm must be investigated. (C) 2011 Elsevier B.V. All rights reserved.

Behavioural and seminal characteristics of Santa Ines rams subjected to successive semen collections in the Amazonian region

The objective of this study was to evaluate the reproductive performance of Santa Ines rams subjected to successive semen collections in an Amazonian climate. Four rams were subjected to successive ejaculations during a maximum period of three hours. This procedure was repeated three times at 15-day intervals. Sexual and behavioural (libido) and andrological (testicular and seminal) assessments were performed. A total of 81 ejaculates were collected. Libido and semen vigour, volume, appearance and concentration decreased as the ejaculation frequency increased (P<0.05) and sperm motility showed a decreasing trend (P=0.06). The seminal pH increased over the sequence of collections (P<0.05). The only significant differences observed between individual rams were the variable scrotal circumference and the percentages of live sperm and sperm abnormalities (P<0.05). All the parameters of the first ejaculation were within the normal range for this species, which suggests that the local climatic conditions (high temperature and humidity) did not affect the behavioural, testicular or seminal parameters of experimental rams. Our findings indicate that the reproductive performance of Santa Ines rams could be affected by the intensification of ejaculation frequency; however, individual male variation needs to be taken into consideration.

Microbial alterations of the soil influenced by induced compaction

A compactação é um dos fatores mais agravantes para a qualidade do solo, porém o seu efeito na comunidade e atividade enzimática microbiana não tem sido suficientemente estudado. Seis níveis de compactação foram obtidos pela passagem de tratores com diferentes pesos em um Latossolo Vermelho, e a densidade final foi medida. Amostras de solo foram coletadas nas profundidades de 0-10 e 10-20 cm, após a colheita do milho. O efeito da compactação foi evidente em todos os parâmetros estudados, mas nem sempre foi significativo. A contagem das bactérias totais reduziu significativamente em 22-30 %, e a das nitrificantes, em 38-41 %, no solo com maior densidade em relação ao controle. Contudo, a população de fungos aumentou de 55 a 86 %, e a das bactérias desnitrificantes, de 49 a 53 %. A atividade da desidrogenase diminuiu de 20 a 34 %; a da urease, de 44 a 46 %; e a da fosfatase, de 26 a 28 %. O conteúdo de matéria orgânica e o pH do solo diminuíram na camada 0-0,10 em relação à de 0,10-0,20 m e influíram possivelmente na redução das contagens microbianas exceto das bactérias desnitrificantes, e na atividade das enzimas, menos a da urease. Esses resultados indicam que a compactação do solo teve influência na comunidade de microrganismos aeróbios e na sua atividade. Esse efeito pode alterar a ciclagem de nutrientes e diminuir a produção da planta.

Behavioural responses of workers towards worker-produced male larvae and queen-produced worker larvae in Acromyrmex subterraneus brunneus Forel, 1911 (Hym., Formicidae)

Leaf-cutting ant workers care for larvae with an elaborate behavioural repertoire to satisfy the needs of the offspring. In order to investigate worker discrimination ability in the leaf-cutting ant Acromyrmex subterraneus brunneus, we compared the behavioural responses of workers towards worker-produced male larvae and queen-produced worker larvae, including the following behavioural acts: licking the larval body, transporting larvae, feeding larvae with hyphae, scraping larval mouth parts, ingesting faecal fluid excreted by the larva, and inserting hyphae of the symbiontic fungus on the larval body. We verified that workers behaved differently depending on larval origin, i.e. licking the larval body, transporting larvae and inserting hyphae of the symbiontic fungus on the larval body. Observed differences denote the ability of workers in discriminating among larvae, probably because of their different individual needs.

Morphological and physiological alterations induced by lactofen in soybean leaves are reduced with nitric oxide

O lactofen é um herbicida difeniléter recomendado para controlar plantas daninhas de folhas largas em campos de soja (Glycine max) e seu mecanismo de ação é a inibição da protoporfirinogênio-IX oxidase (Protox), que atua na biossíntese de clorofilas. Essa inibição resulta em um acúmulo de protoporfirina-IX, o que leva à produção de espécies reativas de oxigênio (ROS), causando estresse oxidativo. Conseqüentemente, podem ocorrer manchas, enrugamento e queima das folhas, o que leva à paralisação temporária do crescimento da cultura. Porém, o óxido nítrico (NO) atua como um antioxidante na eliminação direta das ROS. Assim, o objetivo deste trabalho foi verificar, por meio de avaliações fitométricas e bioquímicas, o efeito protetor do NO em plantas de soja tratadas com o herbicida lactofen. Plantas de soja foram pré-tratadas com diferentes doses de Nitroprussiato de Sódio (SNP), substância doadora de NO, e então pulverizadas com 168 g a.i. ha-1 lactofen. O pré-tratamento com SNP foi benéfico, pois o NO reduziu os sintomas de injúria causados pelo lactofen nos folíolos jovens e manteve baixos teores de açúcares solúveis. Porém, o NO proporcionou crescimento mais lento das plantas. Desta forma, posteriores estudos são necessários para elucidar os mecanismos de ação do NO na sinalização do estresse promovido pelo lactofen na cultura da soja.

Dexamethasone treatment in vivo counteracts the functional pancreatic islet alterations caused by malnourishment in rats

The effects of dexamethasone (Dex) on the metabolic parameters, peripheral insulin, and glucose sensitivity in vivo as well as on islet function ex vivo of rats submitted to low-protein diet were analyzed. Dexamethasone (1.0 mg/kg body weight) was administered intraperitoneally daily to adult Wistar rats fed on a normal-protein diet or low-protein diet (LPD) for 5 days, whereas control rats fed on a normal-protein diet or low-protein diet (LP) received saline alone. At the end of the experimental period, LP rats showed a significant reduction in serum insulin, total serum protein, and serum albumin levels compared with rats fed on a normal-protein diet (P < .05). All these parameters tended to be normalized in LPD rats (P < .05); furthermore, these rats exhibited increased serum glucose and nonesterified fatty acid levels compared with LP rats (P < .05). Rats submitted to the low-protein diet demonstrated normal peripheral glucose sensitivity and improved peripheral insulin sensitivity, which was reversed by Dex treatment. A reduced area of islets from LP rats was partially recovered in LPD rats (P < .05). At 16.7 mmol/L glucose, insulin secretion from LPD islets was also partially recovered and was significantly higher than that from LP islets (P < .05). In conclusion, induction of insulin resistance by Dex treatment reverses most of the metabolic alterations in rats submitted to a low-protein diet. In addition, several islet functions were also improved by Dex, confirming the plasticity of pancreatic islets in adverse conditions. (C) 2008 Elsevier B.V. All rights reserved.

Functional alterations in endocrine pancreas of rats with different degrees of dexamethasone-induced insulin resistance

Objectives: We have analyzed the peripheral insulin and glucose sensitivity in vivo, and islet function ex vivo in rats with different degrees of insulin resistance induced by dexamethasone (DEX).Methods: Dexamethasone, in the concentrations of 0.1 (DEX 0.1), 0.5 (DEX 0.5), and 1.0 mg/kg body weight (DEX 1.0) was administered daily, intraperitoneally, to adult Wistar rats for 5 days, whereas controls received saline.Results: Dexamethasone treatment induced peripheral insulin resistance in a dose-dependent manner. At the end of the treatment, only DEX 1.0 rats showed significant increase of postabsorptive blood glucose and serum triglycerides, and nonesterified fatty acids levels. Incubation of pancreatic islets in increasing glucose concentrations (2.8-22 mM) led to an augmented insulin secretion in all DEX-treated rats. Leucine, carbachol, and high KCl concentrations induced the insulin release in DEX 0.5 and DEX 1.0, whereas arginine augmented secretion in all DEX-treated groups.Conclusions: We demonstrate that in DEX 0.5 and, especially in DEX 0.1 groups, but not in DEX 1.0, the adaptations that occurred in the endocrine pancreas are able to counteract metabolic disorders (glucose intolerance and dyslipidemia). These animal models seem to be interesting approaches for the study of degrees of subjacent effects that may mediate type 2 diabetes (DEX 1.0) and islet function alterations, without collateral effects (DEX 0.1 and DEX 0.5).

Pancreatic islets from dexamethasone-treated rats show alterations in global gene expression and mitochondrial pathways

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alterations in the intestinal wall due to protein malnutrition in rats. Evaluation of the rupture strength and the tissue's collagen

OBJETIVO: Avaliar o efeito da desnutrição protéica na parede intestinal do rato através da medida de força de ruptura e dosagem do colágeno tecidual no íleo e cólon distal. MÉTODOS: Foram utilizados 120 ratos, pesando em média 100g, que receberam durante 07 dias uma dieta padrão, contendo 20% de caseína para adaptação dos animais as condições do biotério. Após esse período os animais foram divididos em dois grupos de 60, o controle denominado grupo um que recebeu a dieta padrão, e o grupo teste denominado grupo dois, que recebeu dieta hipoprotéica contendo 2% de caseína. Os dois grupos receberam suas respectivas dietas por um período de 21 dias. Após esse período iniciou-se o sacrifício seqüencial dos animais em ambos os grupos, em número de 12 animais em cada momento, correspondendo ao dia Zero (MO), 4º dia (M1), 7º dia (M2), 14º dia (M3), e 21º dia (M4) sendo mantida a mesma dieta até o final do sacrifício. em cada momento foram avaliados o peso corpóreo, albumina sanguínea, hidroxiprolina tecidual, relação hidroxiprolina/proteína tecidual e a força de ruptura no segmento ileal e cólico dos animais. RESULTADOS: Observou-se que a força de ruptura do segmento ileal e do cólon distal foi menor nos animais desnutridos (Grupo 2). A perda da resistência mecânica foi maior no segmento do cólon distal do que no segmento ileal, provavelmente pela menor concentração do colágeno tecidual no cólon distal. CONCLUSÃO: A desnutrição protéica induz a diminuição da resistência mecânica no íleo e no cólon distal associado a diminuição do colágeno tecidual na parede intestinal.