Brain and kidney GHS-R1a underexpression is associated with changes in renal function and hemodynamics during neurogenic hypertension.

Ghrelin is a peptide hormone whose effects are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), mainly expressed in the brain but also in kidneys. The hypothesis herein raised is that GHS-R1a would be player in the renal contribution to the neurogenic hypertension pathophysiology. To investigate GHS-R1a role on renal function and hemodynamics, we used Wistar (WT) and spontaneously hypertensive rats (SHR). First, we assessed the effect of systemically injected vehicle, ghrelin, GHS-R1a antagonist PF04628935, ghrelin plus PF04628935 or GHS-R1a synthetic agonist MK-677 in WT and SHR rats housed in metabolic cages (24 h). Blood and urine samples were also analyzed. Then, we assessed the GHS-R1a contribution to the control of renal vasomotion and hemodynamics in WT and SHR. Finally, we assessed the GHS-R1a levels in brain areas, aorta, renal artery, renal cortex and medulla of WT and SHR rats using western blot. We found that ghrelin and MK-677 changed osmolarity parameters of SHR, in a GHS-R1a-dependent manner. GHS-R1a antagonism reduced the urinary Na+ and K+ and creatinine clearance in WT but not in SHR. Ghrelin reduced arterial pressure and increased renal artery conductance in SHR. GHS-R1a protein levels were decreased in the kidney and brain areas of SHR when compared to WT. Therefore, GHS-R1a role in the control of renal function and hemodynamics during neurogenic hypertension seem to be different, and this may be related to brain and kidney GHS-R1a downregulation.

Ghrelin potentiates cardiac reactivity to stress by modulating sympathetic control and beta-adrenergic response.

Prior evidence indicates that ghrelin is involved in the integration of cardiovascular functions and behavioral responses. Ghrelin actions are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), which is expressed in peripheral tissues and central areas involved in the control of cardiovascular responses to stress. AIMS: In the present study, we assessed the role of ghrelin - GHS-R1a axis in the cardiovascular reactivity to acute emotional stress in rats. MAIN METHODS AND KEY FINDINGS: Ghrelin potentiated the tachycardia evoked by restraint and air jet stresses, which was reverted by GHS-R1a blockade. Evaluation of the autonomic balance revealed that the sympathetic branch modulates the ghrelin-evoked positive chronotropy. In isolated hearts, the perfusion with ghrelin potentiated the contractile responses caused by stimulation of the beta-adrenergic receptor, without altering the amplitude of the responses evoked by acetylcholine. Experiments in isolated cardiomyocytes revealed that ghrelin amplified the increases in calcium transient changes evoked by isoproterenol. SIGNIFICANCE: Taken together, our results indicate that the Ghrelin-GHS-R1a axis potentiates the magnitude of stress-evoked tachycardia by modulating the autonomic nervous system and peripheral mechanisms, strongly relying on the activation of cardiac calcium transient and beta-adrenergic receptors.

Production and chemical composition of hybrid Brachiaria cv. Mulato II under a system of cuts and nitrogen fertilization / Produção e composição bromatológica da Brachiaria híbrida cv. Mulato II sob regime de cortes e adubação nitrogenada

The production capacity of green and dry mass of the entire plant, efficiency of N conversion, apparent N recovery and the chemical composition of cultivar Mulato II was evaluated under a system of cuts and nitrogen doses. The assay, conducted in the municipality of Goiânia, GO, Brazil, had a totally randomized 2 x 4 factorial design (2 height cuts, 0.40 and 0.50 m and 4 nitrogen doses), with three replications and subdivided subplots. Treatments comprised four N doses (0, 50, 100 and 150 kgha-1 N, with urea as nitrogen source). There was no significant interaction (p>0.05) between N doses and cut heights for the variables productivity of green (PGM) and dry (PDM) mass, nitrogen use efficiency (NUE) and apparent N recovery (ANR), which were neither affected (p<0.05) by N doses nor by evaluated cut heights. Average productivity reached 59,450 kgha-1 (PGV) and 10,367 kgha-1 (PDM) and it was produced an average of 19.62 kg of DM per kg of N, with a mean 56.00% recovery. N doses and cut heights did not affect (p>0.05) DM rates of the plant, whilst mean dry matter rate was 17.49%. CP rates were affected (p<0.05) by N doses (0, 50, 100 and 150 kgha-1) and cut heights (0.40 and 0.50 m) and by the interaction of these factors. CP rates of the entire plant hybrid Brachiaria cv. Mulato II increased (p<0.05) due to N doses through an increasing linear relationship. Since there was a significant effect (p<0.05) with regard to cut height and CP rates decreased with height increase. NDF rates were significantly influenced by N doses (p<0.05) and by cut heights (p<0.05), with significance for the interaction (p<0.05) of over 100 kgha-1 N doses only. No significant interaction (p>0.05) occurred in ADF rates among the variables analyzed. ADF contents were influenced by N supply (p<0.05) with decreasing quadratic regression as N doses increased.

O presente trabalho de pesquisa teve como objetivo avaliar o potencial produtivo de massa verde e seca da planta inteira, a eficiência de conversão do N, a recuperação aparente do N, bem como a composição bromatológica do cultivar Mulato II, sob regime de cortes e submetido a doses de nitrogênio, no município de Goiânia, GO, Brasil. Utilizou-se um delineamento experimental inteiramente casualizado com arranjo fatorial 2 X 4 (2 alturas de corte (0,40 e 0,50 m) X 4 doses de nitrogênio) com três repetições e parcelas subdivididas. Os tratamentos foram constituídos por quatro doses de N (0, 50, 100 e 150 kgha-1 de N) (sendo a fonte ureia). Não ocorreu interação significativa (p>0,05) entre doses de N e alturas de corte para as variáveis produtividades de massa verde (PMV) e massa seca (PMS), eficiência de conversão aparente de nitrogênio (ECAN) e recuperação aparente de nitrogênio (RAN), que não foram influenciadas (p<0,05) pelas doses de N, nem em função das alturas de corte avaliadas. A média de produtividade encontrada foi de 59.450 kgha-1 (PMV) e 10.367 kgha-1 (PMS), produzindo em média 19,62 kg de MS para cada kg de N aplicado, com uma recuperação média de 56,00%. As doses de N aplicadas e as alturas de corte não influenciaram (p>0,05) os teores de MS da planta. A média do teor de matéria seca encontrada foi de 17,49%. Os teores de PB foram influenciados (p<0,05) pelas doses de N (0, 50, 100 e 150 kgha-1) e alturas de corte (0,40 e 0,50 m) bem como a interação desses fatores. Os teores de proteína bruta (PB) da planta inteira Brachiaria híbrida cv. Mulato II aumentaram (p<0,05) em função das doses de N, apresentando uma relação linear crescente. Quanto à altura de corte, ocorreu também efeito significativo (p<0,05), evidenciando que os teores de PB diminuíram com o aumento da altura. Os teores de FDN foram influenciados significativamente pelas doses de N (p<0,05) e pelas alturas de corte (p<0,05), apresentando significância para a interação (p<0,05) apenas nas doses acima de 100 kgha-1 de N. Para os teores de FDA não houve interação significativa (p>0,05) entre as variáveis analisadas. O conteúdo de FDA foi influenciado pelo fornecimento de N (p<0,05), apresentando regressão quadrática decrescente com o aumento das doses de N.

Central activities of hydroalcoholic extract from Lafoensia pacari A. St.-Hil. stem bark / Atividades centrais do extrato de Lafoensia pacari A. St.- Hil. da casca do caule

Lafoensia pacari A. St.-Hil. can be found from Amapá to Rio Grande do Sul states, and also in Paraguay and Bolivia. It is popularly known as pacari or mangava-brava and is used to promote weight loss, as an anti-thermal or tonic, to treat gastritis, ulcers, scarring, itching, discouragement, and cancer. In the open field tests, the hydroalcoholic extract from L. pacari stem bark (HEP) decreased the number of rearings, number of invaded squares, and increased immobility time compared to control animals. In the pentobarbital-induced sleep time test, HEP decreased latency time to sleep and increased sleeping time. In the rota-rod test, no changes in the studied parameters were observed. In the elevated plus maze, HEP increased the percentage time and percentage entries in the open arms, indicating that this extract exerts an anxiolytic-like activity.

Lafoensia pacari A. St.-Hil., uma espécie vegetal presente no Brasil, do Amapá ao Rio Grande do Sul, no Paraguai e na Bolívia, é popularmente conhecida como pacari ou mangava-brava e é utilizada como emagrecedor, cicatrizante, antitérmico, tônico e para tratar gastrite, úlcera, coceira, desânimo e câncer. No teste do campo aberto, o tratamento com o extrato hidro-alcoólico de pacari (HEP) reduziu o número de rearings e o número de quadrados invadidos além de aumentar o tempo de imobilidade dos animais em relação ao controle. No sono induzido por pentobarbital sódico o tratamento com HEP causou redução na latência e aumento na duração do sono. No rota-rod, o tratamento com HEP não alterou os parâmetros observados. No teste de labirinto em cruz elevado, com o tratamento com HEP foi observado aumento do percentual do tempo de permanência e de entradas nos braços abertos, caracterizando uma atividade tipo ansiolítica.

Avaliação dos efeitos do tratamento com zinco orgânico sobre a reprodução e no comportamento de ratas (Rattus norvegicus) / Evaluation of the organic zinc treatment effects in female rat (Rattus norvegicus) reproduction and behaviour / Evaluación de los efectos del tratamiento con zinc orgánico sobre la reproducción y comportamiento de ratas (rattus norvegicus)

O objetivo do presente trabalho foi avaliar o efeito do tratamento com zinco orgânico no desempenho reprodutivo e no comportamento, por meio de testes de natação forçada, campo aberto e sono induzido por barbitúrico. Foram utilizadas 21 ratas Wistar (Rattus norvegicus), distribuídas em três grupos de sete animals cada, acomodadas em caixas individuais, submetidas a diferentes tratamentos: SZn (controle - sem zinco); ZnP (zinco na forma quelada, por via intramuscular); ZnO (zinco orgânico na dieta, 5 mg/kg). Não foram observadas diferenças estatísticas entre os tratamentos SZn (10,4 ± 2,4 filhotes), ZnP (6,9 ± 2,6 filhotes) e ZnO (3,3 ± 2,6 filhotes), com relação ao desempenho reprodutivo. No teste de desespero comportamental, os tempos de imobilidade dos animals tratados com SZn (91,1 ± 15 seg.), ZnP (71,2 ± 17 seg.) e ZnO (79,9 ± 20 seg.) não apresentaram diferenças estatísticas (p > 0,05). Na avaliação hipno-sedativa, não foram observadas diferenças estatísticas (p > 0,05) no tempo de indução (SZn = 6,6 ± 2; ZnP = 5,3 ± 2; ZnO = 3,6 ± 0,3 min.), nem no tempo de recuperação (SZn = 295 ± 15; ZnP = 320 ± 34; ZnO = 355 ± 38 min.). Os outros parâmetros comportamentais avaliados (número de levantamentos, auto-limpeza, tempo na periferia e número de quadrados invadidos) também não foram influenciados (p > 0,05). Concluiu-se que o zinco, na forma orgânica, administrado via parenteral ou oral, não influencia a reprodução nem o comportamento de ratas.

This article aims at evaluating the effects of the organic zinc treatment over the reproductive performance and behavior through forced swimming tests, open field, and barbiturate-induced sleep. 21 female Wistar rats (Rattus norvegicus) were used, distributed into three groups of seven animals, placed in individual boxes, and submitted to different treatments: SZn (control- without zinc), ZnP (zinc for intramuscular administration), and ZnO (organic zinc in the diet, 5 mg/kg). Statistic differences were not observed (p> 0,05) among the treatments SZn (10.4 ± 2.4 nestlings), ZnP (6.9 ± 2.6 nestlings), and ZnO (3.3 ± 2.6 nestlings), in relation to the number ofnestlings. In the behavioral despair test, the immobility time of the animals treated with SZn (91.1 ± 15 seg.), ZnP (71.2 ± 17 seg.), and ZnO (79.9 ± 20 seg) did not present any statistic differences (p > 0,05). Statistic differences (p> 0,05) were neither present at the induction time (SZn = 6.6 ± 2; ZnP = 5.3 ± 2; ZnO = 3.6 ± 0.3 min), nor in the recovery time (SZn = 295 ± 15; ZnP = 320 ± 34; ZnO = 355 ± 38 min) at the hypno-sedative evaluation. The other behavioral parameters evaluated (number of risings, self-cleaning, time in the periphery, and number of invaded squares) were not altered as well. It was concluded that zinc, in its organic form, either parenterally or orally administered, neither influences the reproduction nor the behavior of female rats.