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1.
IET Syst Biol ; 4(3): 177-84, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20499998

RESUMO

Cyclic dominance of species is a potential mechanism for maintaining biodiversity. The author investigates the generalised scenario when the cyclic dominance of three or more interacting species is described by a non-symmetric matrix game that has multiple Nash equilibria. Modified Lotka-Volterra equations are proposed to incorporate the effects of swarming, and the condition for biodiversity is derived. The species are modelled using replicator equations, where each member of the species is assigned a fitness value. The authors show, for the first time, that the 'swarming effect' has an important role to play in the maintenance of biodiversity. The authors have also discovered the existence of a critical value of the swarming parameter for a given mobility, above which there is a high probability of existence of biodiversity.


Assuntos
Biodiversidade , Evolução Biológica , Aglomeração/fisiopatologia , Teoria dos Jogos , Modelos Biológicos , Dinâmica Populacional , Animais , Simulação por Computador , Humanos
2.
Phys Rev E Stat Nonlin Soft Matter Phys ; 80(3 Pt 2): 036110, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19905183

RESUMO

In this paper, two important factors which affect the pedestrian outflow at a bottleneck significantly are studied in detail to analyze the effect of an obstacle setup in front of an exit. One is a conflict at an exit when pedestrians evacuate from a room. We use floor field model for simulating such behavior, which is a well-studied pedestrian model using cellular automata. The conflicts have been taken into account by the friction parameter. However, the friction parameter so far is a constant and does not depend on the number of the pedestrians conflicting at the same time. Thus, we have improved the friction parameter by the frictional function, which is a function of the number of the pedestrians involved in the conflict. Second, we have presented the cost of turning of pedestrians at the exit. Since pedestrians have inertia, their walking speeds decrease when they turn and the pedestrian outflow decreases. The validity of the extended model, which includes the frictional function and the turning function, is supported by the comparison of a mean-field theory and real experiments. We have observed that the pedestrian flow increases when we put an obstacle in front of an exit in our real experiments. The analytical results clearly explains the mechanism of the effect of the obstacle, i.e., the obstacle blocks pedestrians moving to the exit and decreases the average number of pedestrians involved in the conflict. We have also found that an obstacle works more effectively when we shift it from the center since pedestrians go through the exit with less turning.


Assuntos
Aglomeração/fisiopatologia , Marcha/fisiologia , Locomoção/fisiologia , Modelos Biológicos , Movimento/fisiologia , Simulação por Computador , Fricção , Humanos
3.
IEEE Comput Graph Appl ; 29(4): 34-43, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19798861

RESUMO

Simulating a natural-looking virtual populace requires modeling different behavioral levels to mimic how people choose and organize their activities. A multilayer behavior model for crowd simulation can help developers endow each entity with high-level objectives built on top of a reactive and cognitive decision system.


Assuntos
Gráficos por Computador , Simulação por Computador , Aglomeração/fisiopatologia , Aglomeração/psicologia , Dinâmica Populacional , Interface Usuário-Computador , Cognição/fisiologia , Tomada de Decisões/fisiologia , Humanos , Imageamento Tridimensional , Modelos Biológicos , Atividade Motora/fisiologia
4.
J Anim Sci ; 87(11): 3490-505, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19648504

RESUMO

As a first step toward the genetic mapping of QTL affecting stress response variation in rainbow trout, we performed complex segregation analyses (CSA) fitting mixed inheritance models of plasma cortisol by using Bayesian methods in large full-sib families of rainbow trout. To date, no studies have been conducted to determine the mode of inheritance of stress response as measured by plasma cortisol response when using a crowding stress paradigm and CSA in rainbow trout. The main objective of this study was to determine the mode of inheritance of plasma cortisol after a crowding stress. The results from fitting mixed inheritance models with Bayesian CSA suggest that 1 or more major genes with dominant cortisol-decreasing alleles and small additive genetic effects of a large number of independent genes likely underlie the genetic variation of plasma cortisol in the rainbow trout families evaluated. Plasma cortisol is genetically determined, with heritabilities of 0.22 to 0.39. Furthermore, a major gene with an additive effect of -42 ng/mL (approximately 1.0 genetic SD) is segregating in this rainbow trout broodstock population. These findings provide a basis for designing and executing genome-wide linkage studies to identify QTL for stress response in rainbow trout broodstock and markers for selective breeding.


Assuntos
Oncorhynchus mykiss/genética , Estresse Fisiológico/genética , Animais , Teorema de Bayes , Aglomeração/fisiopatologia , Feminino , Loci Gênicos/genética , Genótipo , Hidrocortisona/sangue , Masculino , Modelos Genéticos , Locos de Características Quantitativas/genética
5.
Am J Physiol Regul Integr Comp Physiol ; 297(2): R313-22, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19458274

RESUMO

Gulf toadfish (Opsanus beta) use a unique pulsatile urea excretion mechanism that allows urea to be voided in large pulses via the periodic insertion or activation of a branchial urea transporter. The precise cellular and subcellular location of the facilitated diffusion mechanism(s) remains unclear. An in vitro basolateral membrane vesicle (BLMV) preparation was used to test the hypothesis that urea movement across the gill basolateral membrane occurs through a cortisol-sensitive carrier-mediated mechanism. Toadfish BLMVs demonstrated two components of urea uptake: a linear element at high external urea concentrations, and a phloretin-sensitive saturable constituent (K(m) = 0.24 mmol/l; V(max) = 6.95 micromol x mg protein(-1) x h(-1)) at low urea concentrations (<1 mmol/l). BLMV urea transport in toadfish was unaffected by in vitro treatment with ouabain, N-ethylmaleimide, or the absence of sodium, conditions that are known to inhibit sodium-coupled and proton-coupled urea transport in vertebrates. Transport kinetics were temperature sensitive with a Q(10) > 2, further suggestive of carrier-mediated processes. Our data provide evidence that a basolateral urea facilitated transporter accelerates the movement of urea between the plasma and gills to enable the pulsatile excretion of urea. Furthermore, in vivo infusion of cortisol caused a significant 4.3-fold reduction in BLMV urea transport capacity in lab-crowded fish, suggesting that cortisol inhibits the recruitment of urea transporters to the basolateral membrane, which may ultimately affect the size of the urea pulse event in gulf toadfish.


Assuntos
Batracoidiformes/metabolismo , Transporte Biológico/fisiologia , Membrana Celular/metabolismo , Brânquias/metabolismo , Hidrocortisona/farmacologia , Ureia/metabolismo , 4-Cloromercuriobenzenossulfonato/farmacologia , Acetamidas/farmacologia , Animais , Transporte Biológico/efeitos dos fármacos , Aglomeração/fisiopatologia , Células Epiteliais/metabolismo , Brânquias/citologia , Hidrocortisona/administração & dosagem , Hidrocortisona/sangue , Cinética , Compostos de Metilureia/farmacologia , Floretina/farmacologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Temperatura , Tioureia/farmacologia , Ureia/análogos & derivados
6.
IUBMB Life ; 61(6): 607-12, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19472183

RESUMO

Dauer is a dormancy state that may occur at the end of developmental stage L1 or L2 of Caenorhabditis elegans when the environmental conditions are unfavorable (e.g., lack of food, high temperature, or overcrowding) for further growth. Dauer is a nonaging duration that does not affect the postdauer adult lifespan. Major molecular events would include the sensing of the environmental cues, the transduction of the signals into the cells, and the subsequent integration of the signals that result in the corresponding alteration of the metabolism and morphology of the organism. Genetics approach has been effectively used in identifying many of the so-called daf genes involved in dauer formation using C. elegans as the model. Nevertheless, biochemical studies at the protein and metabolic level has been lacking behind in understanding this important life phenomenon. This review focuses on the biochemical understanding so far achieved on dauer formation and dormancy in general, as well as important issues that need to be addressed in the future.


Assuntos
Caenorhabditis elegans/crescimento & desenvolvimento , Adaptação Fisiológica , Animais , Caenorhabditis elegans/fisiologia , Aglomeração/fisiopatologia , Proteínas de Choque Térmico/fisiologia , Larva/metabolismo , Larva/fisiologia , Transdução de Sinais
7.
Vet Res Commun ; 33(7): 619-29, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19205917

RESUMO

Farmed fish are usually exposed to routine procedures which have strong effects on stress responses. Rodlet cells may represent an useful biomarker for studies on the presence of stressors in aquaculture. This work focused on the localization of rodlet cells by light and electron microscopy in gills of sea bass (Dicentrarchus labrax) subjected to different conditions of overcrowding. In general, a significant increase in number of rodlet cells has been observed in all animals subjected to overcrowding stress. In gills of control group rare rodlet cells were detected at the level of both primary and secondary lamellae, whereas in stressed group clusters of rodlet cells have been found in the epithelium of primary and secondary lamellae indicating that these cells are influenced by stocking density.


Assuntos
Bass/fisiologia , Aglomeração/fisiopatologia , Doenças dos Peixes/fisiopatologia , Animais , Aquicultura , Biomarcadores/análise , Fenômenos Fisiológicos Celulares , Células/ultraestrutura , Exposição Ambiental , Doenças dos Peixes/etiologia , Brânquias , Hidrocortisona/análise , Densidade Demográfica , Água do Mar
8.
PLoS One ; 3(5): e2100, 2008 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-18461123

RESUMO

BACKGROUND: Tuberculosis (TB) in prisons is a major health problem in countries of high and intermediate TB endemicity such as Brazil. For operational reasons, TB control strategies in prisons cannot be compared through population based intervention studies. METHODOLOGY/PRINCIPAL FINDINGS: A mathematical model is proposed to simulate the TB dynamics in prison and evaluate the potential impact on active TB prevalence of several intervention strategies. The TB dynamics with the ongoing program was simulated over a 10 year period in a Rio de Janeiro prison (TB prevalence 4.6 %). Then, a simulation of the DOTS strategy reaching the objective of 70 % of bacteriologically-positive cases detected and 85 % of detected cases cured was performed; this strategy reduced only to 2.8% the average predicted TB prevalence after 5 years. Adding TB detection at entry point to DOTS strategy had no major effect on the predicted active TB prevalence. But, adding further a yearly X-ray mass screening of inmates reduced the predicted active TB prevalence below 1%. Furthermore, according to this model, after applying this strategy during 2 years (three annual screenings), the TB burden would be reduced and the active TB prevalence could be kept at a low level by associating X-ray screening at entry point and DOTS. CONCLUSIONS/SIGNIFICANCE: We have shown that X-ray mass screenings should be considered to control TB in highly endemic prison. Prisons with different levels of TB prevalence could be examined thanks to this model which provides a rational tool for public health deciders.


Assuntos
Aglomeração/fisiopatologia , Prisioneiros/estatística & dados numéricos , Prisões/estatística & dados numéricos , Tuberculose/prevenção & controle , Brasil/epidemiologia , Humanos , Programas de Rastreamento , Modelos Estatísticos , Prisões/normas , Radiografia Torácica , Tuberculose/diagnóstico por imagem , Tuberculose/epidemiologia , Tuberculose/transmissão
9.
J Physiol Pharmacol ; 59(1): 163-75, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18441396

RESUMO

The present study was designed to determine the involvement of nitric oxide (NO) and prostaglandins (PG) in the stimulatory action of clenbuterol, a selective beta(2)-adrenergic receptor agonist on hypothalamic-pituitary-adrenal (HPA) axis under basal and social crowding stress conditions. Clenbuterol given i.c.v. (10 microg) or i.p. (0.2 mg/kg) considerably increased ACTH and corticosterone secretion. A selective beta(2)-receptor antagonist compound ICI 118551 and non-selective beta-receptor antagonist propranolol given by either route reduced the stimulatory action of clenbuterol. Crowding stress (21 rats in a cage for 7) for 3-7 days significantly reduced the i.c.v. clenbuterol-induced ACTH and corticosterone secretion and i.p. clenbuterol-elicited ACTH secretion. L-NAME, mainly endothelial nitric oxide synthase (NOS) blocker, stronger than L-NNA, a neuronal NOS blocker, reduced the clenbuterol-evoked ACTH and corticosterone secretion in control rats but did not significantly alter this secretion already reduced by crowding stress. Piroxicam, predominantly constitutive cyclooxygenase (COX-1) inhibitor, given i.p. significantly diminished the i.p. clenbuterol-induced ACTH and corticosterone secretion in control rats and tended to reverse the reduction of ACTH secretion by crowding stress. These results indicate that clenbuterol, a selective beta(2)-adrenoceptor agonist, is much stronger stimulator of the HPA axis than isoprenaline, a non-selective beta-receptor agonist. Social crowding stress reduces to a larger extent the HPA response to beta(2)-receptor stimulation. Likewise, in the HPA axis stimulation via beta(2)-adrenoceptors endogenous NO and prostaglandins are significantly involved. Beta2-adrenoceptor is a dominant functional subtype of beta-receptor in the stimulatory and modulatory signals regulating the HPA axis activity under basal and social stress conditions.


Assuntos
Agonistas Adrenérgicos beta/farmacologia , Hormônio Adrenocorticotrópico/efeitos dos fármacos , Clembuterol/farmacologia , Corticosterona/metabolismo , Óxido Nítrico/metabolismo , Agonistas Adrenérgicos beta/administração & dosagem , Hormônio Adrenocorticotrópico/metabolismo , Animais , Clembuterol/administração & dosagem , Aglomeração/fisiopatologia , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Sistema Hipotálamo-Hipofisário/fisiopatologia , Injeções Intraperitoneais , Injeções Intraventriculares , Masculino , Sistema Hipófise-Suprarrenal/efeitos dos fármacos , Sistema Hipófise-Suprarrenal/fisiopatologia , Prostaglandinas/metabolismo , Ratos , Ratos Wistar , Receptores Adrenérgicos beta 2/efeitos dos fármacos , Receptores Adrenérgicos beta 2/metabolismo , Estresse Psicológico/fisiopatologia
10.
Gen Comp Endocrinol ; 155(1): 227-33, 2008 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-17559851

RESUMO

Proopiomelanocortin (POMC) is an important gene implicated in different functions, such as the stress response of the hypothalamus-pituitary-adrenal axis. The aim of the present study was to determine whether farming conditions, such as stocking density, can be considered a powerful stressor influencing in turn the growth rate in juvenile fish. Thus, POMC cDNA expression was investigated during adaptation to farming conditions in sole (Solea solea), as a model for studying the effects of rearing densities on stress response; different stocking densities (50, 100, and 250 animals/m(2)) were applied and, after 7 and 21 days, the fishes were examined for body weight and plasma cortisol levels as indicators of stress. In addition, proopiomelanocortin was cloned and sequenced from the brain of sole, allowing semi-quantitative RT-PCR to be performed to evaluate POMC mRNA expression in brain tissue. There was a significant increase in cortisol levels in fish reared at high stocking densities of 250/m(2) compared to fish reared at control densities of 100 and 50/m(2), in both experimental times, i.e., 7 and 21 days. The high stocking densities were also found to decrease the specific growth rate of fish. Moreover, it was demonstrated that the highest stocking density induced a significant decrease in sole POMC mRNA expression. It is concluded that POMC and cortisol are both involved in the stress response due to high rearing densities, during which cortisol may serve as a negative regulator of POMC.


Assuntos
Aglomeração/fisiopatologia , Linguados/crescimento & desenvolvimento , Linguados/genética , Pró-Opiomelanocortina/genética , RNA Mensageiro/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Peso Corporal/fisiologia , Clonagem Molecular , DNA Complementar/isolamento & purificação , Linguados/sangue , Regulação da Expressão Gênica , Hidrocortisona/sangue , Dados de Sequência Molecular , Densidade Demográfica , Pró-Opiomelanocortina/metabolismo , Homologia de Sequência de Aminoácidos
11.
J Physiol Pharmacol ; 58(3): 487-501, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17928645

RESUMO

The study investigated the effect of chronic crowding stress on vascular function and nitric oxide (NO) production in rats with various family history of hypertension. Wistar (W), wBHR (offspring of W dams and spontaneously hypertensive sires), sBHR (offspring of spontaneously hypertensive dams and W sires) and spontaneously hypertensive rats (SHR) were used. Twelve-week-old males were divided into the control or crowded group for eight weeks. Basal blood pressure (BP, determined by tail-cuff plethysmography) of W, wBHR, sBHR and SHR rats was 112 +/- 3, 129 +/- 2, 135 +/- 2 and 187 +/- 3 mmHg, respectively. Crowding increased BP and reduced aortic NO synthase activity only in sBHR and SHR rats, without alterations in hypothalamic NO production. Acetylcholine-induced vasorelaxation of the femoral artery of stress-exposed rats was improved in W, unaltered in wBHR and sBHR and reduced in SHR. Crowding reduced serotonin-induced vasoconstriction in W and wBHR rats but had no effect in sBHR and SHR rats. In conclusion, the results suggest that crowded offspring of normotensive mothers were able to modify their vascular function in order to maintain BP at normal levels. On the other hand, offspring of hypertensive mothers were unable of effective adaptation of vascular function in stressful conditions resulting in gradual development of hypertension.


Assuntos
Artéria Femoral/fisiopatologia , Hipertensão/fisiopatologia , Óxido Nítrico/metabolismo , Estresse Psicológico/fisiopatologia , Acetilcolina/farmacologia , Animais , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/metabolismo , Peso Corporal/fisiologia , Aglomeração/fisiopatologia , Aglomeração/psicologia , Relação Dose-Resposta a Droga , Feminino , Artéria Femoral/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Hipertensão/genética , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Técnicas In Vitro , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Norepinefrina/farmacologia , Ratos , Ratos Endogâmicos SHR , Ratos Wistar , Serotonina/farmacologia , Comportamento Social , Especificidade da Espécie , Vasodilatação/efeitos dos fármacos
12.
Clin Infect Dis ; 44(8): 1051-6, 2007 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-17366448

RESUMO

BACKGROUND: Denmark's systems of registry-based data offer a unique opportunity to examine, on a population basis, risk factors for invasive pneumococcal disease (IPD) relating to perinatal and crowding exposures among children. The main objective of this study was to identify the role of familial and day care factors in the risk of IPD among unvaccinated infants and children. METHODS: A total of 1381 children aged 0-5 years old who experienced IPD were identified from a national surveillance program of IPD in Denmark. Risk factors were assessed in a matched, nested, case-control study that assigned 10 population control subjects to every case patient. Exposure information was obtained from several population-based, person-identifiable Danish registries. RESULTS: Preterm birth and low birth weight significantly increased the risk of IPD among infants. In infants 0-5 months of age, the risk of IPD was high among infants who had older siblings, compared with infants of the same age who had no older siblings (adjusted rate ratio [aRR], 3.38; 95% confidence interval, 2.11-5.42), whereas the aRR was low (aRR, 0.56; 95% confidence interval, 0.47-0.65) in children aged 6-23 months. Day care attendance, compared with home care, increased the aRR of IPD 0-2 months after enrollment in a day care program (aRR, 2.28; 95% confidence interval, 1.73-3.00), whereas the aRR was 0.70; (95% confidence interval, 0.46-1.06) > or = 6 months after enrollment in children aged 6-23 months. CONCLUSIONS: During infancy (age, 0-6 months), risk of IPD is associated with low birth weight, presumably because of lower levels of passively acquired maternal antibody. During early childhood, exposure to other young children (either siblings or through day care attendance) is clearly associated with IPD, but natural exposure appears to occur rapidly and confer durable immunity.


Assuntos
Aglomeração/fisiopatologia , Assistência Perinatal , Infecções Pneumocócicas/epidemiologia , Streptococcus pneumoniae , Estudos de Casos e Controles , Criança , Humanos , Lactente , Assistência Perinatal/métodos , Infecções Pneumocócicas/prevenção & controle , Vacinas Pneumocócicas , Vigilância da População , Fatores de Risco
13.
Biol Lett ; 3(2): 128-30, 2007 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-17264051

RESUMO

Telomeres are DNA-protein complexes at the ends of chromosomes that control genomic integrity but appear to become shorter with age and stress. To test whether stress causes telomere attrition, we exposed the offspring of wild-caught house mice (Mus musculus) to stressful conditions and examined the changes in telomere length over six months. We found that females exposed to males and reproductive stress (either with or without crowding) had significantly shorter telomeres than controls, and males exposed to crowding stress had shorter telomeres than males that were not crowded. Our results indicate that stress alters telomere dynamics, causing attrition and hindering restoration, and these effects are sex dependent. Telomeres may thus provide a biomarker for assessing an individual's cumulative exposure or ability to cope with stressful conditions.


Assuntos
Aglomeração/fisiopatologia , Camundongos/fisiologia , Estresse Fisiológico/genética , Telômero/fisiologia , Animais , Feminino , Masculino , Camundongos/genética , Reprodução/fisiologia , Fatores Sexuais , Telômero/genética
14.
Lab Anim (NY) ; 36(2): 28-38, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17245386

RESUMO

Although there is a general consensus that housing conditions affect the well-being of laboratory animals, the ideal cage size and density for housing laboratory rodents has not been established. The authors investigated the effects of cage size and cage density on growth, organ development, metabolic profile, and hemogram in juvenile Sprague-Dawley rats. Larger cages and increased cage density were associated with depressions in body weight and in the weights of several organs. In general, increasing group size and density correlated more strongly with detrimental effects on the growth of females than males, although hemogram values indicated that males are more prone to emotional stress and immune suppression than females in response to increasing group size and crowding.


Assuntos
Aglomeração/fisiopatologia , Abrigo para Animais , Ratos Sprague-Dawley/fisiologia , Animais , Peso Corporal/fisiologia , Testes de Química Clínica , Feminino , Testes Hematológicos , Longevidade/fisiologia , Masculino , Tamanho do Órgão/fisiologia , Ratos , Desmame
15.
J Physiol Pharmacol ; 57(3): 463-77, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17033098

RESUMO

The aim of the present study was to determine the effect of social crowding stress and significance of nitric oxide (NO) and prostaglandins (PG) generated by constitutive and inducible nitric oxide synthase (NOS) and cyclooxygenase (COX) in the stimulation of hypothalamic-pituitary-adrenal (HPA) axis by cholinergic muscarinic receptor agonist carbachol. Inhibitors of neuronal NOS (nNOS) L-NNA, general NOS L-NAME and inducible NOS (iNOS) aminoguanidine, as well as inhibitors of COX-1, piroxicam, and COX-2, compound NS-398 were administered 15 min prior to carbachol to control or crowded rats (24 rats in cage for 7, during 3 and 7 days). In stressed rats L-NAME, L-NNA and aminoguanidine significantly intensified the carbachol-induced ACTH and corticosterone secretion, like in control rats. Piroxicam, markedly decreased the carbachol-induced ACTH and corticosterone response under either basal or stress conditions. Compound NS-398 did not markedly alter the carbachol-induced HPA response in control and stressed rats. Crowding stress (3 days) significantly impaired the i.c.v. prostaglandin E(2)-induced ACTH response. Corticotropin releasing hormone (CRH) receptor antagonists, alpha-helical CRH [9-14], given i.c.v. did not alter the PGE(2)-evoked corticosterone response in either control or stressed rats, indicating that hypothalamic CRH is not involved in the PGE(2)-induced central stimulation of HPA axis. In control rats L-NAME considerably enhanced, while L-arginine, a physiological NOS substrate, abolished the PGE(2)-induced ACTH and corticosterone response. In stressed rats this NOS blocker significantly increased and L-Arg reduced the stimulatory effect of PGE(2) on ACTH and corticosterone secretion. The carbachol-induced corticosterone response was significantly increased by pretreatment with nNOS inhibitor L-NNA and was considerably reduced by indomethacin, a general COX inhibitor. Pretreatment with both antagonists left the carbachol-induced corticosterone level unchanged, suggesting an independent and reciprocal effect of NO and PG in the cholinergic stimulation of pituitary-adrenocortical response. These results indicate that in the stimulatory action of muscarinic agonist, carbachol, NO is an inhibitory transmitter under basal and crowding stress conditions. This psychosocial stress does not functionally affect the NOS/NO systems. Prostaglandins are involved in the cholinergic muscarinic-induced stimulation of HPA response to a significant extent in non-stressed rats. PGE(2) may be involved in the carbachol-elicited HPA response under basal and stress conditions. Prostaglandins released in response to muscarinic stimulation did not evoke the hypothalamic CRH mediation. NO significantly impairs and PG stimulates the carbachol-induced HPA response in rats under basal and social stress conditions.


Assuntos
Aglomeração/fisiopatologia , Sistema Hipotálamo-Hipofisário/fisiopatologia , Óxido Nítrico/metabolismo , Sistema Hipófise-Suprarrenal/fisiopatologia , Prostaglandinas/metabolismo , Estresse Psicológico/fisiopatologia , Acetilcolina/fisiologia , Animais , Colinérgicos/farmacologia , Hormônio Liberador da Corticotropina/antagonistas & inibidores , Dinoprostona/metabolismo , Masculino , Modelos Animais , Óxido Nítrico Sintase/antagonistas & inibidores , Ratos , Ratos Wistar
16.
Artigo em Inglês | MEDLINE | ID: mdl-16714131

RESUMO

The effects of post-crowding swimming velocity (0, 0.35, and 0.70 m/s) and recovery time (1.5, 6, and 12 h) on physiological recovery and processing quality parameters of adult Atlantic salmon (Salmo salar) were determined. Atlantic salmon crowded to a density similar to that of a commercial slaughter process (>200 kg/m(3), 40 min) were transferred to a swimming chamber for recovery treatment. Osmolality and concentrations of cortisol, glucose and lactate in blood plasma were used as physiological stress indicators, whereas image analyses of extent and duration of rigor contraction, and fillet gaping were used as measures of processing quality. Crowded salmon had a 5.8-fold higher plasma cortisol concentration than control salmon (P<0.05). The elevated plasma cortisol concentration was reduced by increasing the swimming velocity, and had returned to control levels after 6 h recovery at high water velocity. Similar effects of swimming velocity were observed for plasma osmolality and lactate concentration. A lower plasma glucose concentration was present in crowded than in control fish (P<0.05), although a typical post-stress elevation in plasma glucose was observed after the recovery treatments. Lower muscle pH was found in crowded compared with control salmon (P<0.05), but muscle pH returned to control levels after 6 h recovery at intermediate and high swimming velocities and after 12 h in the low velocity group. Crowding caused an early onset of rigor mortis contraction. However, subjecting crowded salmon to active swimming for 6 h before slaughter delayed the onset of rigor mortis contraction from 2.5 to 7.5 h post mortem. The extent of rigor mortis contraction was also affected by crowding and post-stress swimming activity (P<0.05), and the largest degree of contraction was found in crowded salmon. In conclusion, active swimming accelerated the return of plasma cortisol, hydromineral balance, and the energy metabolism of adult Atlantic salmon to pre-stress levels. Moreover, an active swimming period delayed the onset of rigor mortis contraction, which has a positive technological implication for the salmon processing industry.


Assuntos
Aglomeração/fisiopatologia , Salmo salar/fisiologia , Natação/fisiologia , Animais , Glicemia/análise , Manobra Psicológica , Hidrocortisona/sangue , Concentração de Íons de Hidrogênio , Ácido Láctico/sangue , Contração Muscular , Músculos/metabolismo , Variações Dependentes do Observador , Concentração Osmolar , Recuperação de Função Fisiológica , Rigor Mortis , Salmo salar/sangue , Fatores de Tempo
17.
J Anim Sci ; 84(3): 588-96, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16478950

RESUMO

Pigs typically experience various environmental stressors, which can negatively affect performance. Cortisol concentrations and various immune and performance measures are influenced by breed, but few data exist describing the impact of breed on stress responsiveness in pigs. The objective of this experiment was to determine if certain physiological responses to chronic stressors differed among 3 breeds and 2 commercial lines of pigs. The pigs were Landrace (n = 36), Meishan (n = 30), Yorkshire (n = 32), or 1 of 2 commercial lines (Line-A and Line-B; both n = 36). All pigs were weaned at 17 to 21 d and kept in a common nursery. At 49 d of age, pigs were assigned to 1 of 2 treatments: stress (heat, crowding, and mixing) or control (no stress treatment). Pigs were allocated to groups of 3 pigs per pen of the same sex. Control pigs were kept with their littermates. At the onset of the experiment, stressed pigs were mixed with 2 unfamiliar pigs once, and heat and crowding stressors were implemented simultaneously for 14 d. Pigs allocated to the stress treatment were video-recorded for 24 h following initiation of mixing to determine social status: dominant, intermediate, or submissive. Blood samples were taken at d 0 (baseline), 1, 7, and 14 to assess cortisol concentrations and immune measures. Breed and treatment affected cortisol, immune, and performance measures, but no significant breed x treatment interactions were found. In general, pigs subjected to the chronic stressor had lower (P < 0.001) BW and ADG (P < 0.001) than did control pigs. Plasma cortisol was lower (P < 0.001) among stressed pigs at d 7 and 14. Regardless of breed, lipopolysaccharide-induced proliferation (P < 0.01) and natural killer (NK; P < 0.005) cytotoxicity were greater in stressed pigs compared with controls. Furthermore, among stressed pigs, dominant pigs had a greater total white blood cell count (P < 0.005), NK (P < 0.05), and phagocytosis (P < 0.05) than the subordinate pigs. The results indicate that pig breed did not influence the physiological responses to the chronic concurrent stressors imposed for 14 d in this study, but social status did influence the immune responsiveness of these pigs to heat, crowding, and mixing.


Assuntos
Comportamento Social , Predomínio Social , Estresse Fisiológico/veterinária , Suínos/fisiologia , Animais , Peso Corporal , Cruzamento , Quimiotaxia de Leucócito , Aglomeração/fisiopatologia , Feminino , Temperatura Alta/efeitos adversos , Hidrocortisona/sangue , Imunoglobulina G/sangue , Células Matadoras Naturais/imunologia , Análise dos Mínimos Quadrados , Contagem de Leucócitos/veterinária , Ativação Linfocitária , Masculino , Neutrófilos/imunologia , Fagocitose , Estresse Fisiológico/fisiopatologia , Gravação em Vídeo
18.
J Vector Ecol ; 31(2): 371-7, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17249355

RESUMO

Alteration of fitness components was assessed in the yellow fever mosquito, Aedes aegypti, in automobile tires and vases (ovitraps) under field conditions. Larval numbers were manipulated in both kinds of containers to compare low, high, and control (natural) densities. Densities were set from a census of a wild population, then doubling and reducing to half the mean crowding, m*. Artificially altered densities were not high or low enough to produce differences among treatments. Tires generated more vigorous larval populations and females with higher fecundity than did small containers, although the mortality was more intense.


Assuntos
Aedes/crescimento & desenvolvimento , Aglomeração/fisiopatologia , Oviparidade/fisiologia , Animais , Argentina , Biomassa , Peso Corporal , Feminino , Larva/crescimento & desenvolvimento , Masculino , Controle de Mosquitos , Densidade Demográfica , Pupa
19.
Artigo em Inglês | MEDLINE | ID: mdl-16309937

RESUMO

Our previous results have shown that metabolic and thermal stressors influence interscapular brown adipose tissue (IBAT) metabolic activity by increasing oxygen consumption and, consequently, altering the toxic reactive oxygen species (ROS) production and the antioxidative system activity. Since there is not enough evidence about the effect of psychosocial stressors on these processes, we studied the effect of acute crowding stress on the IBAT and hypothalamic monoamine oxidase (MAO) activity as well as IBAT antioxidative enzymes, manganese (MnSOD), copper-zinc superoxide dismutase (CuZnSOD) and catalase (CAT), as the relevant indicators of IBAT metabolic alternations under the stress exposure and the returning of animals to control conditions. The results indicated that acute crowding stress did not change the hypothalamic and IBAT MAO activities, the generation of ROS and, consequently, the IBAT CuZnSOD and CAT activities. However, all three antioxidative enzymes were affected only after the recovery period. It seems that peripheral overheating of rats during acute crowding changes the stress nature, by becoming more thermal than psychosocial and by suppression the hypothalamic efferent pathways involved in the IBAT thermogenesis regulation. However, it seems that returning of the animals to the control conditions after the stress termination causes the reactivation of IBAT thermogenesis with tendency to normalise the body temperature.


Assuntos
Tecido Adiposo Marrom/metabolismo , Aglomeração/fisiopatologia , Estresse Fisiológico/fisiopatologia , Animais , Temperatura Corporal , Catalase/metabolismo , Hipotálamo/enzimologia , Masculino , Monoaminoxidase/metabolismo , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo
20.
Mol Cell Biochem ; 276(1-2): 21-9, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16132681

RESUMO

Although neurochemical changes have been reported in the brain in animal models of binge eating, biochemical changes of specific proteins in the brain are unknown. Our aim was to elucidate brain proteins altered in rats during enhanced rebound hyperphargia. Rats were deprived of food for 22 h/day for 6 days, then allowed free access to food for 24 h in normal cages (rebound hyperphargia) or in space-restricted cages (enhanced rebound hyperphargia). Proteins extracted from the rat brain were separated by two-dimensional gel electrophoresis, and compared with those from control rats freely fed for 7 days in normal cages. Proteins expressed differently from controls were identified by N-terminal amino acid sequencing and mass fingerprinting using a MALDI-TOF mass spectrometer. Among proteins in the corpus striatum, frontal lobe, hippocampus and thalamus/hypothalamus, ubiquitin C-terminal hydrolase L1 and peroxiredoxin 2 decreased in the hippocampus and phosphatidylethanolamine-binding protein increased in the thalamus/hypothalamus of rats with the enhanced rebound hyperphargia induced by space-restriction. In this study, we first demonstrated that three brain proteins changed in rats during enhanced rebound hyperphagia. These proteins might have pathophysiologic relevance to binge eating.


Assuntos
Encéfalo/metabolismo , Aglomeração/fisiopatologia , Hiperfagia/metabolismo , Animais , Comportamento Animal/fisiologia , Comportamento Alimentar , Feminino , Proteômica , Ratos , Ratos Wistar , Restrição Física
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