Rodent Research Articles

Research on the Etiology of Skin Diseases in Laboratory Animals

The objective of this study was to establish derma tological diseases etiology in laboratory animals. Were examined clinically and de rmatologically a number of 403 rodents of different ages and sexes, respectively 173 guinea p igs ( Cavia porcellus ), 120 rabbits ( Orytolagus cuniculus ), 80 rats ( Rattus norvegicus ) and 30 mice ( Mus musculus ). Dermatological diseases identified in guinea pigs were represented by malop hagosis ( Gliricola porcelli in 111/173 - 64,16%), listrophorosis ( Chirodiscoides caviae in 111/173 - 64,16%), demodicosis ( Demodex caviae in 2/173 - 1,15%) and tricophytosis ( Trichophyton mentagrophytes in 3/173 - 1,73%). Rats were infected only with Notoedres muris (56/80 respectively 70%). In rabbits was diagnosed ( Psoroptes cuniculi in 7/120 - 5,83%), listrophorosis ( Listrophorus gibbus in 2/120 - 1,66%) and cheyletiellosis ( Cheiletiella parasitovorax in 2/120 - 1,66% ). In mice have evolved associate d infestations with Mycoptes musculinus (20/30 - 66,66%), Myobia musculi (12/30 - 40%) and Chirodiscoides caviae (3/30 - 10%). Chirodiscoides caviae, mite with specific parasitism in guinea pig, has be en isolated from mice with skin lesions. Were recorded two zoonotic diseases: tricophytosis and cheyletiellosis.

Bird's nesting success and eggs predation within Arusa National Park, Arusha, Tanzania

Nesting success and eggs predation is among the factors that affect the population dynamics of bird species. The study was carried out to determine predation impact on selected bird species population in Arusha National Park, Arusha, Tanzania. Specifically the study assessed the potential predators to ground (Scaly Francolin) and (Ruppell’s Robin- Chat, Striped-cheeked Greenbul, Tambourine Dove and Tropical Boubou) to establish if nesting success and eggs predation vary with habitat fragments types and nesting heights. Artificial nests were constructed in three different heights, and both artificial and true eggs were put on the nests in eleven habitat fragments and their associated forests. Identification of predators was obtained indirectly through punched signs left by predators on artificial and true eggs. Observation was done daily and data were analyzed both qualitatively and quantitatively. The study showed no significant difference in predation effect on eggs in glade versus glade edge X2 = 3.08, Df = 1, P > 0 .05, glade edge versus forest interior X2 = 0.04, Df = 1, P > 0 .05, while glade versus forest interior showed to differ significantly X2 = 0.08, Df =1, P 0 .05 in level 1, X2 = 3.81, Df = 2, P > 0.05 at level 2 and X2 = 0.67, Df = 2, P > 0. 05 at level 3. The percentage egg failure was 41.54 % with predation effects contributing 92% of the total impact, followed by floods 5% and trampling 3%. Although habitat predation varied among habitat types and vertical levels, the type of predators did not vary. However, among predators rodents contributed the highest level of predation effects. Nesting failure was a result of predation, trampling and flooding with the later two affecting more the ground nester birds’ species. Key words: Predators, birds’ population, edge effects, Tanzania

Pharmacological effects of methanolic extract of Swietenia mahagoni Jacq (meliaceae) seeds

Seeds of medicinal plants are common ingredients of many folk and herbal medicines, and seed extracts have been reported to possess pharmacological activity including anti-inflammatory activity. In the present investigation, the methanolic extract of the dried ground seeds of Swietenia mahagoni (SMSE) has been evaluated for anti-inflammatory, analgesic, and antipyretic activities. The anti-inflammatory activity was evaluated using acute, sub-chronic, and chronic models of inflammation in rodents. The antipyretic and analgesic activities were evaluated in mice models. Acute toxicity studies revealed that the extract up to a dose of 1.2 g/kg intraperitoneally was nontoxic. SMSE at doses of 50 and 100 mg/kg, i.p. was found to possess anti-inflammatory, analgesic, and antipyretic activities and the effect was comparable with that produced by the standard drug, ibuprofen. The results of the experiment on arachidonic acid-induced paw edema in rat revealed that the extract produces anti-inflammatory activity through dual inhibition of the cyclo-oxygenase and lipo-oxygenase pathways of arachidonic acid metabolism. SMSE also enhanced peritoneal cell exudates along with macrophage significantly. The triterpenoids present in SMSE may be responsible for these activities. SMSE possesses antiinflammatory, analgesic, and antipyretic activities. Key words: Swietenia mahagoni seed, triterpenoids, anti-inflammatory, analgesic, antipyretic effects

Pathway-specific variations in neurovascular and neurometabolic coupling in rodent brain

Pathway-specific variations in neurovascular and neurometabolic coupling in rodent brain

Depressant-like effects of parthenolide in a rodent behavioural antidepressant test battery

The anti-serotonergic effects of parthenolide (PTL) demonstrated in platelets inspired the present psychopharmacological investigation, which employs a battery of rodent behavioural assays of depression. In mice, PTL (0.5-2 mg kg(-1)) exhibited dose-dependent depressant-like effects in a forced swim test and a tail suspension test, without affecting the baseline locomotor status. The doses (1 and 2 mg kg(-1)) that induced depressant-like effects were found to significantly reduce 5-hydroxytryptophan-induced head twitch response. Interaction studies revealed that the depressant-like effects of PTL (1 mg kg(-1)) were reversed more efficiently by serotonergic antidepressants (venlafaxine, escitalopram, citalopram, fluoxetine) than by others (desipramine, bupropion) tested. Chronic treatment of PTL (1 and 2 mg kg(-1)) augmented the hyper-emotionality of olfactory bulbectomized rats, when compared with sham rats, as observed in modified open field, elevated plus maze and social interaction paradigms. This study depicts the severe depressogenic potential of PTL (in its pure form) plausibly mediated by platelet/neuronal hypo-serotonergic effects.

Inflammation interferes with the assessment of vitamin A status in magnesium deficiency.

Hyporetinemia is observed in several pathological conditions including a primary deficiency of vitamin A and has also been reported to accompany inflammatory diseases. Experimental magnesium (Mg) deficiency in rodents is accompanied by an inflammatory syndrome. The present study was designed to determine whether the acute phase response in Mg-deficient rats can modify vitamin A status. Clinical symptoms of acute phase response were observed in Mg-deficient rats and were accompanied by a reduction in plasma retinol and of plasma retinol binding protein (RBP). Mg deficiency in rats resulted in hyporetinemia without a significant decrease in liver retinol reserves. Consequently, the data strongly suggest that the decrease in plasma retinol concentration, resulting from the level of its binding protein, is related to the inflammatory effect of Mg deficiency. These results point to the possible interference of Mg deficiency on the use of plasma retinol as an indicator of vitamin A status.

Emmonsiosis of rodents in an agroecosystem

Emmonsiosis of rodents in an agroecosystem

Aging-associated changes in cardiac function and their prevention

Aging associated changes in cardiac contraction, Ca(2+) homeostasis and their neurohumoral regulations have been studied using rodents. The changes can be understood not only to reduce energy consumption but also to be susceptible to Ca(2+) overload, possibly leading arrhythmia and cell death. N-3 polyunsaturated fatty acid is reported to prevent cardiac Ca(2+) overload. Its content in the cellular membrane is reduced in aged cardiomyocytes, suggesting that the aging-associated change in n-3 fatty acid content is related to the changes in cardiac function. Ingestion balance between n-3 and n-6 fatty acids may affect on the risk of cardiovascular diseases associated with aging.

Pivotal role reelin signaling pathway in the development of tolerance to morphine-induced antinociception

The huge endogenous macromolecule protein responsible for controlling migration and dendritic growth of developing neurons, reelin, has recently been proposed that its signaling pathway modulates synaptic plasticity in the adult rodent brain. This study was carried out to investigate the pivotal role of the reelin signaling pathway in the development of tolerance to morphine induced antinociception. There was evidence that repeated intracerebroventricular administration of reelin’s monoclonal antibody, the competitive inhibitor to reelin – apolipoprotein receptor E2 recombinant, and disabled1 (Dab1) protein inhibitor – MG132, resulted in the inhibition to the development of antinociception tolerance to morphine administration. Furthermore, chronic in vivo administration with morphine caused significance increase of the immunoreactivity (IR) for phosphorylated-Dab1 in the thalamus. These data suggested that persistent activation of reelin signaling pathway due to chronic administration of morphine may be responsible for the development of tolerance to morphine-induced antinociception. Key words: Morphine tolerance, Neuronal plasticity, Opioid receptor, Reelin signalling pathway

Antidepressant effects of total tertiary alkaloid fraction of Cissampelos sympodialis Eichler in rodents

A proposta deste trabalho foi de avaliar os efeitos da fracao de alcaloides terciarios totais (TTAF) de Cissampelos sympodialis Eichler (Menispermaceae) em dois modelos animais de depressao: a) teste do nado forcado e b) teste da reserpina. O tratamento de camundongos com TTAF (12,5 mg/kg) reduziu o tempo total de imobilidade dos animais. Tambem reverteu a hipotermia induzida por reserpina, demonstrando um efeito antidepressivo nos dois modelos. Adicionalmente, o tratamento com TTAF nao modificou a ambulacao e o comportamento de levantar das patas dianteiras dos animais avaliados no teste do campo aberto, realizado no intuito de investigar se a reducao no tempo de imobilidade apresentada no teste do nado forcado foi causada por estimulacao na atividade locomotora. Como a warifteina e um dos principais alcaloides presente na TTAF da C. sympodialis, e tem atividade inibidora da enzima fosfodiesterase, ela pode ser responsavel pelo efeito antidepressivo observado na fracao estudada.

Rodents rake in rewards

Rodents rake in rewards

Intraocular pressure measurement in rodents

The ability to measure intraocular pressure in rodents is very important for the advancement of glaucoma research. This review article describes various currently used methods, such as, microcannulation, servo-null micropipette, Tonopen tonometer, rebound tonometer, Goldmann applanation tonometer, Schiötz indentation tonometer, pneumatonometer, and optic interferometry tonometer. Their principles of operation, advantages and limitations, as well as a calibration method are also discussed.

Rodents

Rodents

Un bel libro sui roditori italiani

Un bel libro sui roditori italiani

Acute itching models in rodents

瘙痒是一种引起搔抓刺激部位欲望的感觉,搔抓行为已被用于评价实验动物的瘙痒和作为临床观察瘙痒的客观指标.组胺、5-羟色胺、P物质、白三烯B4和血小板激活因子等致痒介质均可使啮齿动物出现剂量依赖性搔抓行为.迄今只有几个可靠的外周激发瘙痒动物模型.大鼠颈背部皮内注射5-羟色胺诱导的搔抓行为是目前较为理想的急性瘙痒动物模型,其发生机制与皮肤中5-羟色胺2受体激活有关,但与组胺和5-羟色胺3受体无关。

Distribution of aquaporins in the nasal passage of Octodon degus, a South-American desert rodent and its implications for water conservation

Los roedores de ambientes aridos y semiaridos viven bajo una disponibilidad limitada de agua tanto espacial como temporal. Octodon degus es un roedor sudamericano que habita ambientes aridos y semiaridos del norte y zona central de Chile. Su supervivencia depende de adaptaciones morfologicas, fisiologicas y conductuales que permiten optimizar la conservacion de agua. Este tiene una alta capacidad de concentracion urinaria y de deshidratacion de la fecas ademas de una baja tasa de evaporacion pulmocutanea, relacionada con la capacidad de los pasajes nasales para condensar agua contenida en el aire espirado; el agua condensada debe ser absorbida en orden de evitar su acumulacion y potencial perdida por las fosas nasales. Nuestra hipotesis es que el epitelio de los pasajes nasales expresaria acuaporinas (AQPs) que podrian servir como una via rapida de absorcion del agua condensada. Se estudio la distribucion de AQP-1, AQP-2, AQP-3 y AQP-4 mediante inmunocitoquimica en cortes provenientes de animales controles y sometidos a un periodo de restriccion acuosa. Se detecto abundante inmunorreactividad para AQP-1 en la red vascular subepitelial, no se detecto expresion de AQP-1 en el epitelio de los pasajes nasales. No se detecto ni AQP-2 ni AQP-4 en el mismo epitelio. Se detecto inmunorreactividad para AQP-3 en el epitelio no olfatorio que recubre los turbinales en pasajes nasales estrechos y ciegos. No se evidenciaron cambios en la abundancia de inmunorreactividad para AQP-3 entre ambos grupos. La inmunorreactividad para AQP-1 subepitelial y para AQP-3 epitelial coincide a nivel de los turbinales, aunque en diferentes tipos celulares; ello sugiere que estas acuaporinas podrian servir como una via para la absorcion de agua desde la superficie de los pasajes nasales, via AQP-3 hacia los capilares subepiteliales a traves de AQP-1

How does sampling protocol affect the richness and abundance of small mammals recorded in tropical forest? An example from the Atlantic Forest, Brazil

Small mammals are important elements of tropical forests but there is not a protocol for sampling these animals. In this study, we aimed at evaluating which sampling design maximizes the richness and/or the abundance of small mammals in a given area. We used data available in studies carried out in the Brazilian Atlantic forest. The variables analyzed for each study were number of marsupial species, number of rodent species, number of marsupial individuals and number of rodent individuals (dependent variables), sampling effort (trap-nights), design (grid or transect), number of strata sampled, number of nights and number of trap types used (independent variables). We did an analysis of covariance using the type of forest (evergreen or semideciduous) as the co-factor and factoring out the sampling effort to verify if the patterns of richness and abundance of species changed between these types of forests. The same analysis was done using the design as the cofactor in different forest types. Therefore, we performed analyses of variance in each forest type using the number of strata sampled, number of traps types and number of nights as factors to verify the effects of these factors on richness and abundance of the species. The capture effort was the most important variable to explain the richness and abundance of small mammals. The forest type influenced the abundance of species. Marsupials seemed to be more abundant in the semideciduous forest and rodents in the evergreen forest. RJ, Brazil.

Smoking Marijuana During Pregnancy

Prenatal marijuana exposure targets cannabinoid receptors in the brain, disrupting central nervous system cellular migration, differentiation, and synapse communication. In rodents, exposure to marijuana during gestation impairs fetal brain development, leading to adverse effects on behavior and cognition. However, results from studies in humans have been inconsistent. To determine the effect of prenatal marijuana exposure on children’s intellectual …

Assessment of cognitive function following magnesium therapy in the traumatically injured brain.

Many studies have examined the preclinical efficacy of Mg2+ therapy in models of traumatic brain injury. However, more of these studies have examined sensorimotor and motor performance than cognitive performance following injury. The present paper reviews the use of Mg2+ therapy to facilitate cognitive recovery in several models of cortical injury in the rodent. The first study examined the ability of daily injections of MgCl2 (1 or 2 mmol) to impair acquisition of a reference memory task in the Morris Water Maze. Additional studies examined the ability of MgCl2 to improve cognitive function following bilateral anterior medial cortex ablations, bilateral frontal cortex contusions, and unilateral frontal contusions. The results from these studies indicate that MgCl2 therapy is biologically active and readily crosses the blood-brain barrier because daily injections of MgCl2 impaired learning of a reference memory task in intact rats. Mg2+ therapy for brain injury revealed that administration of post-injury MgCl2 effectively improved recovery of cognitive deficits following injury. These results suggest that Mg2+ therapy is effective in facilitating cognitive recovery of function following brain injury; however, there are task and dose-dependent aspects to this recovery.

Streptozotocin-induced diabetes is associated with changes in NGF levels in pancreas and brain.

Type 1 diabetes mellitus (DM), a "classical" result of a pancreatic-beta cell damage, is associated with various metabolic, neuronal, endocrine and immune alterations at cellular, tissue and organ levels. Nerve growth factor (NGF) is one of the most extensively studied neurotrophic factors, which is produced and released by numerous cells including the pancreatic beta cells. NGF plays an important role during brain development and may be able to delay or even reverse damaged forebrain cholinergic neurons that undergo degeneration in aged animals and in Alzheimer's disease (AD). Recent reports indicate that experimentally induced DM in rodents can cause brain biochemical and molecular alterations similar to those observed in sporadic AD. Given the importance of NGF in the pathophysiology of brain cholinergic neurons, we looked for NGF changes in the pancreas and brain of diabetic rats. The aim of this study was, therefore, to investigate the effect of streptozotocin-induced DM on NGF and NGF receptor expression in pancreas and brain. The results showed that DM is associated with altered NGF, NGF-receptor expression in both pancreas and brain.