Hypothalamic disconnection caudal to paraventricular nucleus affects cardiovascular and drinking responses to central angiotensin II and carbachol

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

Central mechanisms involved in pilocarpine-induced pressor response

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

Melatonin reduces LH, 17 beta-estradiol and induces differential regulation of sex steroid receptors in reproductive tissues during rat ovulation

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

Antioxidant defense in rat brain regions after developmental lead exposure

Oxidative stress is considered a possible molecular mechanism involved in Pb neurotoxicity. Considering the vulnerability of the developing brain to Pb neurotoxicity, this study was carried out to investigate the effects of low-level developmental Pb exposure on brain regions antioxidant enzymes activities. Wister dams were exposed to 500 ppm of Pb, as Pb acetate, or to 660 ppm Na acetate in the drinking water during pregnancy and lactation. The activities of superoxide dismutase (SOD), glutathione peroxidase and glutathione reductase were determined in the hypothalamus, hippocampus and striatum of male pups at 23 (weaned) or 70 days (adult) of age. In the Pb-exposed 23-day-old pups, the activity of SOD was decreased in the hypothalamus. Regarding adults, there was no significant treatment effect in any of the enzymes and regions evaluated. Based on the present results, it seems that oxidative stress due to decreased antioxidant function may occur in weaned rats but it is suggested that this should not be the main mechanism involved in the neurotoxicity of low-level Pb exposure. (C) 2001 Elsevier B.V. Ireland Ltd. All rights reserved.

Neuroendocrine and reproductive aspects of adult male rats exposed neonatally to an antiestrogen

The present study was designed to investigate the effects of a single dose of an estrogen antagonist-clomiphene-during neonatal life, on later neuroendocrine system and reproductive performance. Immediately after birth, male pups received clomiphene citrate (s.c.). At adulthood, although testosterone levels and wet weights of reproductive organs were not altered, the treatment induced an increased number of spermatozoa and a delay in the transit time in the cauda epididymis. Additionally, there was impairment of sexual behavior evidenced by a delay in the latencies to the first mount and first intromission. Treated rats also showed decreased dopaminergic and serotonergic neurotransmissions in the hypothalamus and decreased dopaminergic neurotransmission in the striatum. The decreased dopaminergic activity could be related to the lower sexual motivation observed. These results indicate the necessity of preventing exposure to drugs that may impair sexual differentiation, which can compromise later mating success as well as the capacity to generate descendants. (c) 2006 Elsevier B.V. All rights reserved.

Puberty installation and adrenergic response of seminal vesicle from rats exposed prenatally to hydrocortisone

We investigated the effects of hydrocortisone during the prenatal period and its repercussion on puberty installation and adrenergic response of seminal vesicle in adult rats. The efficacy of the hydrocortisone treatment in reducing adrenal wet weight immediately after delivery in both the treated mothers and respective pups at birth may indicate impairment of the hypothalamus-pituitary-adrenal axis. This parameter was unchanged in the adult phase of these descendants, suggesting recuperation of this axis. In addition, the treatment with hydrocortisone delayed the age of puberty installation, probably by absence of both physiologic production and liberation of luteinizing hormone and testosterone. Despite the significant reduction in testosterone level as well as of wet weights of both vas deferens and testis in the adult phase, no difference was observed in the sensitivity of the seminal vesicle to the studied sympathetic agonist. However, the observed reduction in contractile response of the seminal vesicle may be a consequence of contractile-system damage in this organ. It is possible that this alteration may cause a reduction in the amount of vesicular secretion so important in the process of ejaculation. In conclusion, these results suggest that administration of hydrocortisone in late prenatal life did not influence the hypothalamus-pituitary-adrenal axis in adult life, although it altered the hypothalamus-pituitary-gonadal axis, and reduced testosterone production starting at puberty, as a consequence of an incomplete masculinization of the hypothalamus plus a reduction in the contractile response of the seminal vesicle. (c) 2005 Elsevier B.V. All rights reserved.

The GABAergic system contributes to the anxiolytic-like effect of essential oil from Cymbopogon citratus (lemongrass)

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

Conditioning of stress in Nile tilapia

A Pavlovian conditioning paradigm was used to induce a connection between a conditioned stimulus, light (CS), associated with an unconditioned stimulus, confinement (US) in Nile tilapia Oreochromis niloticus, which resulted in a conditioned endocrine response (CR) to the CS alone manifested as an increase in plasma cortisol. Individual isolated Nile tilapia were submitted for 10 days to the conditioning treatment consisting of turning on a light (CS) for I min with subsequent 30 min confinement (US). on the 10th day of the experiment, plasma cortisol was not increased when fish were subjected to no handling at all, or only light, or even a daily stressor for the 9 days. on the other hand, at the 10th day cortisol was significantly increased only when light was presented either with or without pairing with the stressor. These results confirmed that the cue, light (CS), was not stressful in itself, but when given as the CS in the absence of the US post conditioning the hypothalamus-pituitary-interrenal axis was activated. Therefore, it was concluded that memory of a previous experience with a stressor can be recalled by a conditioned stimulus and induce stress, which is the first demonstration of a memory-induced stress in fishes. (C) 2004 the Fisheries Society of the British Isles.

Effects of Spider Venom Toxin PWTX-I (6-Hydroxytrypargine) on the Central Nervous System of Rats

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

Biomarcadores de estresse em ratos exercitados por natação em intensidades igual e superior à máxima fase estável de lactato

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

Máxima Fase estável de lactato em ratos obesos de ambos os gêneros

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

Role of central nitric oxide in behavioral thermoregulation of toads during hypoxia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Causas da desnutrição pós-gastrectomia

Racional A retirada total ou parcial do estômago resulta em conseqüências nutricionais, agudas ou crônicas, perfeitamente prognosticáveis, mas nem sempre ponderadas na terapia pós-operatória. Objetivo - Rever as participações mecânicas e químicas do estômago no aproveitamento do nutriente dietético, e as conseqüências nutricionais da gastrectomia. Resultados - A deficiência energética, com conseqüente perda de peso, acompanha inversamente o volume gástrico remanescente e o tempo pós-operatório; tem a anorexia e diarréia (má absorção) como principais causas, sendo a primeira decorrente de fatores emocionais ou de mediadores químicos de ação hipotalâmica. A diarréia pode ser decorrente da maior motilidade ou do supercrescimento bacteriano intestinais, com o agravante da insuficiência pancreática exócrina e maior esvaziamento da vesícula biliar. A má absorção traz conseqüências não apenas energética-protéica com a perda fecal de gordura e nitrogênio, como também vitamínico-mineral pelo menor aproveitamento da vitamina D e cálcio dietéticos. A anemia verificada no gastrectomizado é conseqüente à diminuição da produção de HCl (e menor solubilização do ferro) e do fator intrínseco (com menor absorção da vitamina B12). Conclusão - Perda de peso e anemia são os sinais de desnutrição mais comumente observados nestes pacientes, em intensidade e duração variáveis dependentes do tipo de cirurgia e do tempo e tratamento nutricional pós-operatório, sendo recomendável o tratamento dietético supervisionado.

Aspectos genéticos do hipotireoidismo congênito

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

O papel dos hormônios leptina e grelina na gênese da obesidade

A prevalência da obesidade está aumentando e estudos prospectivos mostram que, em 2025, o Brasil será o quinto país do mundo a apresentar problemas de obesidade em sua população. A etiologia da obesidade não é de fácil identificação, uma vez que a mesma é caracterizada como uma doença multifatorial, ou seja, diversos fatores estão envolvidos em sua gênese, incluindo fatores genéticos, psicológicos, metabólicos e ambientais. Pesquisas recentes na área de metabolismo mostram que o adipócito é capaz de sintetizar várias substâncias e, diferentemente do que se supunha anteriormente, o tecido adiposo não é apenas um sítio de armazenamento de triglicérides, é hoje considerado um órgão endócrino. Dentre as diversas substâncias sintetizadas pelo adipócito, destacam-se a adiponectina, a angiotensina e a leptina. A leptina é um petídeo que desempenha importante papel na regulação da ingestão alimentar e no gasto energético, gerando um aumento na queima de energia e diminuindo a ingestão alimentar. Além dos avanços no estudo da célula adiposa, um novo hormôrnio relacionado ao metabolismo foi descoberto recentemente, a grelina. A grelina é um peptídeo produzido nas células do estômago, e está diretamente envolvida na regulação do balanço energético a curto prazo. Assim, este artigo abordará o papel da leptina e da grelina no controle do peso corporal e as limitações que ainda existem para tratar a obesidade em humanos.