Molecular Genetic Variability, Population Structure and Mating System in Tropical Forages

Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyse population structure and genetic diversity, evolution and origin of the genetic variability in the centre of origin, mating systems and genetic resources in EMBRAPA’s germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed the need in some cases for further plant collection to adequately represent the species in PGR collections, allowed us to assemble core collections (subsets of the total collections) that should contain most of the available diversity and (in the case of the legumes) showed the need to avoid unwanted outcrossing when regenerating conserved material. The data will allow plant breeders to better select accessions for hybrid production, discriminate between genotypes and use marker-assisted selection in breeding programs. Our results will also underpin the construction of genetic maps, mapping of genes of agronomic interest and numerous other studies on genetic variability, population structure, gene flow and reproductive systems for the tropical forage species studied in this work

Chronic treatment with ivabradine does not affect cardiovascular autonomic control in rats.

A low resting heart rate (HR) would be of great benefit in cardiovascular diseases. Ivabradine-a novel selective inhibitor of hyperpolarization-activated cyclic nucleotide gated (HCN) channels- has emerged as a promising HR lowering drug. Its effects on the autonomic HR control are little known. This study assessed the effects of chronic treatment with ivabradine on the modulatory, reflex and tonic cardiovascular autonomic control and on the renal sympathetic nerve activity (RSNA). Male Wistar rats were divided in 2 groups, receiving intraperitoneal injections of vehicle (VEH) or ivabradine (IVA) during 7 or 8 consecutive days. Rats were submitted to vessels cannulation to perform arterial blood pressure (AP) and HR recordings in freely moving rats. Time series of resting pulse interval and systolic AP were used to measure cardiovascular variability parameters. We also assessed the baroreflex, chemoreflex and the Bezold-Jarish reflex sensitivities. To better evaluate the effects of ivabradine on the autonomic control of the heart, we performed sympathetic and vagal autonomic blockade. As expected, ivabradine-treated rats showed a lower resting (VEH: 362 ? 16 bpm vs. IVA: 260 ? 14 bpm, p = 0.0005) and intrinsic HR (VEH: 369 ? 9 bpm vs. IVA: 326 ? 11 bpm, p = 0.0146). However, the chronic treatment with ivabradine did not change normalized HR spectral parameters LF (nu) (VEH: 24.2 ? 4.6 vs. IVA: 29.8 ? 6.4; p > 0.05); HF (nu) (VEH: 75.1 ? 3.7 vs. IVA: 69.2 ? 5.8; p > 0.05), any cardiovascular reflexes, neither the tonic autonomic control of the HR (tonic sympathovagal index; VEH: 0.91? 0.02 vs. IVA: 0.88 ? 0.03, p = 0.3494). We performed the AP, HR and RSNA recordings in urethane-anesthetized rats. The chronic treatment with ivabradine reduced the resting HR (VEH: 364 ? 12 bpm vs. IVA: 207 ? 11 bpm, p < 0.0001), without affecting RSNA (VEH: 117 ? 16 vs. IVA: 120 ? 9 spikes/s, p = 0.9100) and mean arterial pressure (VEH: 70 ? 4 vs. IVA: 77 ? 6 mmHg, p = 0.3293). Our results suggest that, in health rats, the long-term treatment with ivabradine directly reduces the HR without changing the RSNA modulation and the reflex and tonic autonomic control of the heart

Tobacco-free cigarette smoke exposure induces anxiety and panic-related behaviours in male wistar rats.

Smokers, who generally present with lung damage, are more anxious than non-smokers and have an associated augmented risk of panic. Considering that lung damage signals specific neural pathways that are related to affective responses, the aim of the present study was to evaluate the influence of pulmonary injury on anxiety and panic-like behaviours in animals exposed to cigarette smoke with and without tobacco. Male Wistar rats were divided into the following groups: a control group (CG); a regular cigarette group (RC); and a tobacco-free cigarette (TFC) group. Animals were exposed to twelve cigarettes per day for eight consecutive days. The animals were then exposed to an elevated T-maze and an open field. The RC and TFC groups presented increases in inflammatory cell inflow, antioxidant enzyme activity, and TBARS levels, and a decrease in the GSH/GSSG ratio was observed in the TFC group. Exposure to RC smoke reduced anxiety and panic-related behaviours. On the other hand, TFC induced anxiety and panic-related behaviours. Thus, our results contradict the concept that nicotine is solely accountable for shifted behavioural patterns caused by smoking, in that exposure to TFC smoke causes anxiety and panic-related behaviours.Cigarette smoke exposure is associated with anxiety states. Smokers are more anxious than non-smokers1, while cigarette smoking cessation is associated with increased levels of anxiety and stress, as the nicotine in cigarettes has been shown to have anxiolytic effects2. Moreover, smoking is also associated with an augmented risk of panic attacks, and quitting smoking could help reduce this risk3. Importantly, in a study conducted by Amaring and colleagues, it was reported that 72% of panic disorder patients declared that they were regular smokers at the onset of their disease4. Cigarette smoke is also one of the several agents and environmental factors that can trigger oxidative stress and pulmonary damage5. Cigarette smoke causes cellular recruitment, lipid peroxidation, production of inflammatory mediators, and oxidative stress6?11. For instance, studies in mice have shown that exposure to short-term cigarette smoke evokes an increase in inflammatory cell inflow and oxidative damage6,9. In general, exposure to pollutants induces pulmonary inflammation through the generation of oxidative stress12,13, defined as the imbalance in reactive oxygen species production, to the detriment of the antioxidant defence systems14. Importantly, exposure to ambient air particles not only induces pulmonary inflammation but also behavioural disorders both in humans and in mice15. Currently, the majority of anxiety studies associated with cigarette smoking have focused on the anxiolytic effects of nicotine2. However, it has been shown that lung damage can induce central nervous system responses by activating specific neuronal pathways16,17, which include those linked to affective responses, such as anxiety and panic18. This raises the question of whether the anxiety and panic-type behaviour associated with smoking might be related not only to the nicotine or to tobacco?s other constituents but also to lung damage

New insights on amygdala : basomedial amygdala regulates the physiological response to social novelty.

The amygdala has been associated with a variety of functions linked to physiological, behavioral and endocrine responses during emotional situations. This brain region is comprised of multiple sub-nuclei. These subnuclei belong to the same structure, but may be involved in different functions, thereby making the study of each sub-nuclei important. Yet, the involvement of the basomedial amygdala (BMA) in the regulation of emotional states has yet to be defined. Therefore, the aim of our study was to investigate the regulatory role of the BMA on the responses evoked during a social novelty model and whether the regulatory role depended on an interaction with the dorsomedial hypothalamus (DMH). Our results showed that the chemical inhibition of the BMA by the microinjection of muscimol (c-aminobutyric acid (GABAA) agonist) promoted increases in mean arterial pressure (MAP) and heart rate (HR), whereas the chemical inhibition of regions near the BMA did not induce such cardiovascular changes. In contrast, the BMA chemical activation by the bilateral microinjection of bicuculline methiodide (BMI; GABAA antagonist), blocked the increases in MAP and HR observed when an intruder rat was suddenly introduced into the cage of a resident rat, and confined to the small cage for 15 min. Additionally, the increase in HR and MAP induced by BMA inhibition were eliminated by DMH chemical inhibition. Thus, our data reveal that the BMA is under continuous GABAergic influence, and that its hyperactivation can reduce the physiological response induced by a social novelty condition, possibly by inhibiting DMH neurons

Efeitos da injeção intracerebroventricular da tityustoxina escorpiônica (tstx) sobre o sistema cardiovascular de ratos submetidos à desnutrição proteica.

A Síndrome do envenenamento escorpiônico constitui um problema de saúde pública mundial, com prevalência alta em países subtropicais, principalmente na faixa etária infantil. A Tityustoxina (TsTX), alvo deste estudo, é uma das principais toxinas extraídas do veneno bruto do T. serrulatus e possui toxicidade elevada. Liga-se ao sítio III dos canais para sódio dependentes de voltagem (CSDVs), retarda o processo de inativação destes canais, aumenta a permeabilidade da membrana ao sódio e, consequentemente, eleva a excitabilidade celular. Há indícios de que as alterações cardiovasculares observadas no envenenamento grave decorrem da ação direta destas toxinas sobre o sistema nervoso central (SNC). Adicionalmente, é sabido que alguns fatores, como a saúde prévia do paciente, podem influenciar na sintomatologia do escorpionismo. Neste contexto, a desnutrição também é uma síndrome de importância epidemiológica mundial que acomete, principalmente, crianças em países em desenvolvimento. Dados prévios do nosso grupo de pesquisa mostraram que ratos desnutridos apresentam alterações nos mecanismos de controle cardiovascular. Assim, a hipótese de que a desnutrição pode ser um fator modificador da ação central da TsTX e de seus efeitos decorrentes torna esse modelo um importante instrumento para o entendimento fisiopatológico do escorpionismo. Esse trabalho objetiva avaliar os efeitos da injeção intracerebroventricular (i.c.v.) de TsTX sobre o Sistema Cardiovascular (SC) de ratos Fischer submetidos à desnutrição protéica. Os ratos (n=69) foram divididos em dois grupos: Normonutrido e Desnutrido, que receberam, respectivamente, 15% e 6% de proteína na dieta. Os animais foram submetidos ao implante de cânulas-guia no Ventrículo Lateral Esquerdo para a microinjeção de TsTX e ao implante de cateteres femorais (venosos e arteriais) e eletrodos, para a infusão de drogas e aquisição dos valores de pressão arterial média (PAM) e de freqüência cardíaca (FC). Os resultados mostraram que a desnutrição protéica reduziu o peso corporal e aumentou os níveis basais de PAM e FC. A microinjeção de TsTX (1,74 μg/μL) induziu o aumento de PAM em ambos os grupos, embora este aumento tenha sido menor e ocorrido com maior latência no grupo Desnutrido. Adicionalmente, elevou a FC apenas no grupo Normonutrido, mas provocou óbito em 100% dos animais dos dois grupos. Contudo, o Grupo Desnutrido apresentou maior sobrevida. O bloqueio dos CSDVs com Carbamazepina (50mg/kg; i.p.) atenuou o aumento de PAM evocado pela TsTX e aumentou a sobrevida apenas dos animais normonutridos. O bloqueio dos receptores α1- adrenégicos com Prazosin reduziu os níveis basais de PAM nos dois grupos, sendo essa redução mais acentuada nos ratos desnutridos. No entanto, aumentou os níveis basais de FC apenas no grupo Normonutrido. Já o bloqueio dos receptores muscarínicos com Metil- atropina não modificou os níveis basais de PAM em nenhum grupo, mas aumentou a FC basal no grupo Normonutrido. Adicionalmente, alterou o perfil das respostas pressora e cronotrópica cardíaca resultantes da ação da TsTX (maior aumento de PAM e elevação da FC), exclusivamente no grupo Desnutrido. Contudo, os bloqueios autonômicos não alteraram a sobrevida dos animais. Finalmente, estes resultados sugerem que a desnutrição atenua a sintomatologia decorrente da ação direta da TsTX sobre o SNC, provavelmente, devido à diminuição dos sítios de ligação (CSDVs) para a toxina. Sendo assim, a gravidade dos sintomas evocados pela injeção i.c.v. de TsTX pode estar estreitamente relacionada à intensidade com que esta toxina age sobre o SNC.The scorpion envenomation syndrome is a public health matter in tropical regions around the world, mainly in children. The Tityustoxin (TsTX), the target of our study, is one of the main toxins extracted from the T. serrulatus scorpion venom. It binds to the site III of the voltage-gated sodium channels (VGSC), slowing its inactivation and increasing the membrane permeability to sodium and cellular excitability. There are evidences that the cardiovascular changes observed in severe scorpion envenomation result from the direct action of these toxins on the central nervous system (CNS). Additionally, it is known that some factors as the patient's previous health may influence scorpion symptoms. In this context, undernutrition is also an important global epidemiological syndrome that mainly affects children in developing countries. Previous data from our laboratory have shown that undernourished rats present changes in cardiovascular control mechanisms. Thus, we hypothesized that undernutrition may be a modifying factor for the TsTX central action and its effects makes the undernutrition model an important tool to understand the scorpion envenomation. The objective of this work was to assess the effects of TsTX injection in left lateral ventricle (LLV) on the Cardiovascular System (CS) of Fischer rats submitted to protein restriction diet. Rats (n=69) were divided into two groups: Wellnourished and Undernourished groups, which received, respectively, 15% and 6% of protein in the diet composition. Animals were submitted to guide cannulae implantation into the LLV for TsTX microinjection, femoral catheters (arterial and venous) and electrodes implantation for drugs infusion and mean arterial pressure (MAP) and heart rate values acquisition (HR). Our results showed that the undernutrition model reduced the body weight and increased the MAP and HR baseline values. The TsTX microinjection (1.74 µg/µL) induced a MAP increase in both groups, although this increase was smaller and occurred with higher latency in the Undernourished group. Moreover, the TsTX induced a HR elevation only in the Wellnourished group. It induced death in 100% of the animals from both groups. Nevertheless, the Undernourished group had a greater survival time. The VGSC blockade with Carbamazepine (50mg/kg, i.p.) attenuated the MAP increase evoked by TsTX microinjection and increased the survival time only in Wellnourished group. The α1- adrenergic receptors blockade with Prazosin (1mg/kg/mL; i.v.) reduced MAP basal levels in both groups, mainly in the Undernourished rats. However, there was an increase in HR basal levels only in Wellnourished group. On the other hand, the muscarinicreceptors blockade with methyl-atropine (1mg/kg/mL; i.v.) did not affect MAP basal levels in both groups, although there was an increase in HR only in the Wellnourished group. Additionally, it changes the pressor and chronotropic cardiac responses profile resulting from the TsTX action (higher increase in MAP and HR elevation), exclusively in Undernourished group. Besides, the blockade with both drugs did not modify the survival rate in neither group. Finally, these results suggest that the protein restriction attenuates the manifestations resulting from TsTX action on CNS, probably due to a reduction in biding sites (VGSCs) for TsTX. Thus, the severity of symptoms evoked by TsTX injection in LLV may be closely related with the intensity which this toxin acts on CNS

Participação do hipotálamo dorsomedial nas respostas cardiovasculares promovidas pela Injeção Intracerebroventricular da tityustoxina escorpiônica em ratos.

Programa de Pós-Graduação em Ciências Biológicas. Núcleo de Pesquisas em Ciências Biológicas, Pró-Reitoria de Pesquisa e Pós Graduação, Universidade Federal de Ouro Preto.A síndrome do envenenamento escorpiônico é considerada um importante problema de saúde pública, em países tropicais, devido a sua elevada incidência e potencial gravidade dos sintomas, principalmente em crianças. Alguns estudos apontam a grande sensibilidade do sistema nervoso central (SNC) à ação dos componentes tóxicos do veneno e comprovam que as manifestações cardiorespiratórias, consideradas as principais causa mortis do envenenamento, são decorrentes da ativação do sistema nervoso autônomo, sobretudo, da subdivisão simpática. Entretanto, a origem desta modulação permanece desconhecida. Considerando a importante participação do SNC na gênese das repostas hemodinâmicas e cardíacas evocadas pela ação central da Tityustoxina (TsTX, uma α-toxina extraída do veneno do escorpião Tityus serrulatus) e a semelhança destas respostas àquelas mediadas pelo hipotálamo dorsomedial (HDM) em reações de defesa, o objetivo central deste trabalho foi avaliar a participação do HDM nas respostas cardiovasculares decorrentes da injeção i.c.v. de TsTX em ratos. Para tal, em ratos acordados, avaliamos a influência de injeções i.c.v. de diferentes doses de TsTX (1,74μg; 0,174μg; 0,116μg e 0,087μg) sobre os parâmetros cardiovasculares e sobre a porcentagem de letalidade e o tempo de sobrevida. Também realizamos a correlação temporal entre estes parâmetros. Em ratos anestesiados, avaliamos a influência da injeção i.c.v. de TsTX (0,116μg) sobre os parâmetros cardiovasculares e sobre a atividade simpática renal, e o envolvimento dos receptores GABAérgicos e glutamatérgicos ionotrópicos do HDM sobre as alterações cardiovasculares produzidas pela injeção i.c.v. desta dose de TsTX. Dessa forma, nossos principais achados foram: i) a comprovação de uma elevada sensibilidade do SNC à toxicidade exercida pela TsTX; (ii) a relação dose-dependente entre o recrutamento de estruturas encefálicas e o comprometimento cardiovascular (elevação da PAM e FC); (iii) a constatação de uma alta correlação positiva entre a prematuridade das alterações no ritmo cardíaco e a latência para o agravo destas respostas; (iv) uma elevada correlação positiva entre a latência para o agravo das respostas pressora e taquicárdica e o tempo de sobrevida; (v) o aumento da responsividade do nervo simpático renal e (vi) a fundamental participação dos receptores glutamatérgicos ionotrópicos nas respostas hipertensiva e taquicárdica mediadas pela ação central da TsTX. Nossos dados corroboram a hipótese de que o SNC tem uma participação importante na sintomatologia envolvida no envenenamento escorpiônico e sugerem que os circuitos neurais recrutados pela TsTX, cuja ativação resulta em uma variedade de alterações fisiológicas e comportamentais, dependem da ativação dos diferentes subtipos de receptores glutamatérgicos ionotrópicos presentes no HDM.The scorpion envenoming syndrome is an important public health problem, in tropical countries, due to its high incidence and potential severity of symptoms, mainly in children. Some studies address the high sensitivity of the central nervous system (CNS) to the action of the venom toxic components and show that the cardiorespiratory manifestations, which are considered the main causa mortis of scorpion envenoming, are consequences of the autonomic nervous system activation, especially of the sympathetic pathway. However, the origin of this modulation remains unclear. Considering the important CNS participation on the genesis of the cardiovascular responses evoked by the central action of Tityustoxin (TsTX, a α-type toxin extracted from the Tityus serrulatus scorpion venom), and the similarity of these responses, to those mediated by dorsomedial hypotalamus (DMH) in the cardiovascular responses during defense reaction, the central aim of this work was to evaluate the role of DMH on the cardiovascular responses to TsTX i.c.v. injection in rats. To this end, in awake rats, we evaluated the influence of i.c.v. injections of different TsTX doses (1.74μg; 0.174μg; 0.116μg and 0.087μg) on cardiovascular parameters, on lethality percentage and survival time, and a time correlation between these parameters. In anesthetized rats, we evaluated the influence of TsTX i.c.v. injection (0.116μg) on cardiovascular parameters and renal sympathetic nerve activity, and the involvement of GABA and ionotropic glutamate receptors of HDM on cardiovascular alterations induced by i.c.v. injection of this TsTX dose. Thus, our main findings were: i) the evidence of CNS high sensitivity to TsTX toxicity; (ii) the dose-dependent relationship between brain structures recruitment and the cardiovascular compromise (MAP and HR enhance); (iii) a high positive correlation between prematurity of the changes in heart rate and the latency to the grievance of these responses; (iv) a high positive correlation between latency to the grievance of the pressor and tachycardic responses and survival time; (v) the responsiveness increased of renal sympathetic nerve activity and (vi) the essential participation at glutamate receptors in the hypertensive and tachycardic responses mediated by central action of TsTX. Our data support the hypothesis that CNS plays an important role in the symptomathology of scorpion envenomation and suggest that the central circuit recruited by TsTX, whose activation results in an array of physiological and behavioral changes, depend on the activation of the different subtypes of DMH ionotropic glutamate receptors

The implication of protein malnutrition on cardiovascular control systems in rats

The malnutrition in early life is associated with metabolic changes and cardiovascular impairment in adulthood. Deficient protein intake-mediated hypertension has been observed in clinical and experimental studies. In rats, protein malnutrition also increases the blood pressure and enhances heart rate and sympathetic activity. In this review, we discuss the effects of post-weaning protein malnutrition on the resting mean arterial pressure and heart rate and their variabilities, cardiovascular reflexes sensitivity, cardiac autonomic balance, sympathetic and renin-angiotensin activities and neural plasticity during adult life. These insights reveal an interesting prospect on the autonomic modulation underlying the cardiovascular imbalance and provide relevant information on preventing cardiovascular diseases

What is the role of inflammatory mediators on energy metabolism? DOI: 10.14800/ics.1189

The subclinical and low intensity inflammation, oxidative stress, high calorie and high fat diet patterns are striking features of the obesity. The adipose tissue, through its endocrine function, is associated with the cytokines secretion, such as: IL-4, IL-13, IL-15 and IFN-?, which trigger metabolic changes and possibly modulate the energy metabolism by modifying the biochemical, anthropometric and body composition parameters. This review summarizes scientific evidences about the relationship between such cytokines and mediators which alter the energy metabolism, predisposing or preventing the obesity