Cortisol response to acute stress in jundiá Rhamdia quelen acutely exposed to sub-lethal concentrations of agrichemicals

Exposure to agrichemicals can have deleterious effects on fish, such as disruption of the hypothalamus-pituitary-inter-renal axis (HPI) that could impair the ability of fish to respond to stressors. In this study, fingerlings of the teleost jundiá (Rhamdia quelen) were used to investigate the effects of the commonly used agrichemicals on the fish response to stress. Five common agrichemicals were tested: the fungicide - tebuconazole, the insecticide - methyl-parathion, and the herbicides - atrazine, atrazine + simazine, and glyphosate. Control fishes were not exposed to agrichemicals and standard stressors. In treatments 2-4, the fishes were exposed to sub-lethal concentrations (16.6%, 33.3%, and 50% of the LC50) of each agrichemical for 96 h, and at the end of this period, were subjected to an acute stress-handling stimulus by chasing them with a pen net. In treatments 5-7 (16.6%, 33.3%, and 50% of the LC50), the fishes were exposed to the same concentrations of the agrichemicals without stress stimulus. Treatment 8 consisted of jundiás not exposed to agrichemicals, but was subjected to an acute stress-handling stimulus. Jundiás exposed to methyl-parathion, atrazine + simazine, and glyphosate presented a decreased capacity in exhibiting an adequate response to cope with stress and in maintaining the homeostasis, with cortisol level lower than that in the control fish (P < 0.01). In conclusion, the results of this study clearly demonstrate that the acute exposure to sub-lethal concentrations of methyl-parathion, atrazine + simazine, and glyphosate exert a deleterious effect on the cortisol response to an additional acute stressor in the jundiá fingerlings. © 2008 Elsevier Inc. All rights reserved.

Alterações reprodutivas em ratos machos expostos perinatalmente aos frutos da Solanum lycocarpum

This work employed pregnant rats treated with Solanum lycocarpum unripe fruits (10% in diet) from gestation day (GD) 06 to post-natal day (PND) 07, for the evaluation of the sperm number, daily sperm production and epididymal sperm transit time of the male offspring at PND 60 and PND 90. No differences were observed in the daily sperm production (DSP) and sperm number in the testis of the exposed males at PND 60 and PND 90. Also, no alterations were observed in sperm transit time in the caput epididymis of the exposed males at PND 60 and PND 90. However, a reduced sperm transit time was observed in the corpus/cauda epididymis of the experimental males at PND 90. The last data may explain the reduced sperm number observed in the corpus/cauda epididymis of the experimental male rats at PND 90. These data show that the male rats exposed to S. lycocarpum fruits during gestation did not present alterations in testis sperm production and number, however the sperm transit time through epididymis was impaired, resulting in a decreased number of spermatozoa in epididymis cauda. We conclude that S. lycocarpum may cause imbalance on hypothalamus-pituitary gland axis.

Treatments to optimize the use of artificial insemination and reproductive efficiency in beef cattle under tropical environments

Bos indicus cattle, the preferred genetic group in tropical climates, are characterized by having a lower reproductive efficiency than Bos taurus. The reasons for the poorer reproductive efficiency of the Bos indicus cows include longer lengths of gestation and postpartum anestrus, a short length of estrous behavior with a high incidence of estrus occurring during the dark hours, and puberty at older age and at a higher percentage of body weight relative to mature body weight. Moreover, geography, environment, economics, and social traditions are factors contributing for a lower use of reproductive biotechnologies in tropical environments. Hormonal protocols have been developed to resolve some of the reproductive challenges of the Bos indicus cattle and allow artificial insemination, which is the main strategy to hasten genetic improvement in commercial beef ranches. Most of these treatments use exogenous sources of progesterone associated with strategies to improve the final maturation of the dominant follicle, such as temporary weaning and exogenous gonadotropins. These treatments have caused large impacts on reproductive performance of beef cattle reared under tropical areas. Copyright © 2011 O. G. Sá Filho and J. L. M. Vasconcelos.

Agonistas do GnRH, antagonistas do GnRH e a reprodução assistida: Análogos do GnRH x fertilização in vitro

The agonists of gonadotropin-releasing hormone (GnRH) were introduced in ovarian stimulation for in vitro fertilization to avoid a premature surge of luteinizing hormone. Although they are accompanied by some disadvantages, GnRH agonists have become well accepted in clinical practice, and their use is associated with increased rates of pregnancy. The development of GnRH antagonists capable of blocking the pituitary immediately offered a therapeutic option. Comparative studies between the two analogs have suggested that the use of antagonists is associated with a shorter duration of ovulatory stimulus and a decreased incidence of ovarian hyperstimulation syndrome, while the type of GnRH analogues used show no significant effects on the rates of pregnancy and live birth. However, GnRH agonists have other applications in assisted reproductive technology cycles than the pituitary downregulation.

Progesterone-based strategies to induce ovulation in prepubertal Nellore heifers

Four experiments were conducted to evaluate hormonal strategies to induce ovulation in Nellore heifers. In experiment 1, heifers (N = 1039) received a controlled internal drug release (CIDR) of fourth use (CIDR-4) on Day -12 or no CIDR (CIDR-0). The CIDR was removed on Day 0 in the CIDR-4 treatment, and estrus detection and AI were performed from Days 1 to 7. On Day 8, heifers not detected in estrus were evaluated for CL presence and received the same treatment again, followed by estrus detection and AI from Days 21 to 27. All heifers in experiments 2 (N = 896), 3 (N = 839), and 4 (N = 948) received the CIDR-4 treatment on Day -12. In experiment 2, heifers were randomly assigned to a control group (no additional treatment) or to receive equine chorionic gonadotropin (eCG; 200 IU eCG im) on Day 0. In experiment 3, heifers received the same treatments as in experiment 2, or a treatment that included eCG and estradiol cypionate (ECP) (eCG+ECP; 200 IU im eCG plus 0.5 mg ECP im) on Day 0. In experiment 4, heifers received the treatments described in experiment 3 or only ECP (0.5 mg) on Day 0. In experiments 2 and 3, estrus detection and AI was performed from Days 1 to 7 and on Day 8, heifers not detected in estrus were evaluated for CL presence. In experiment 4, heifers were evaluated for presence of a CL between Days 10 and 14. In experiment 1 heifers treated with CIDR-4 had greater estrus detection, ovulation induction, and pregnancy rates than in the CIDR-0 group. In experiment 2, heifers treated with eCG had greater estrus detection, ovulation induction, and pregnancy rates in 7 days than heifers in the control group. In experiment 3, heifers treated with eCG+ECP had greater estrus detection, ovulation induction, and pregnancy rates than the control and eCG treatments. In experiment 4, ovulation induction was greater for heifers treated with eCG and eCG+ECP relative to control, but did not differ from the ECP treatment. In conclusion, the use of a CIDR of fourth use for 12 days and the addition of eCG and/or ECP at CIDR removal efficiently induced ovulation and increased pregnancy rates in prepubertal Nellore heifers. © 2013 Elsevier Inc.

Influence of chronic exercise on serum cortisol levels in older adults

The circulating level of cortisol is regulated by the hypothalamic-pituitary-adrenal axis through a neuroendocrine feedback circuit. This circuit can be activated by physiological stimuli such as stress, diseases, and exercise. High levels of serum cortisol hormone normally occur as a byproduct of aging, and can cause several types of damage to the organism and exacerbate immunosenescence. There is a great deal of variability in the cortisol response with regard to type, intensity, volume, and frequency of exercise. However, these relationships have been extensively studied with respect to the acute effects of exercise. Despite the well-known effects of acute exercise on cortisol response, it is unclear how it is affected by chronic exercise and the aging process. Therefore, the aim of this study was to conduct a review of studies that attempt to analyze the influence of chronic exercise on serum cortisol hormone in older people. In order to accomplish this goal, a review from 1970 to June 2012 period was performed using the following databases: Biological Abstracts, PsycINFO, PubMed/Medline, and the Web of Science. Eight articles met the criteria used in this study. Based on the included articles, chronic exercise may influence the serum levels of cortisol levels in older people. Despite this evidence, these results may not be generalized to the entire population of older people, given the few number of studies and especially because the studies showed diversity in variables and methodologies. © 2013 European Group for Research into Elderly and Physical Activity (EGREPA).

Mechanisms in the bed nucleus of the stria terminalis involved in control of autonomic and neuroendocrine functions: A review

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

Time-course of neuroendocrine changes and its correlation with hypertension induced by ethanol consumption

Ethanol (ETOH) consumption has been associated with endocrine and autonomic changes, including the development of hypertension. However, the sequence of pathophysiological events underlying the emergence of this effect is poorly understood. Aims: This study aimed to establish a time-course correlation between neuroendocrine and cardiovascular changes contributing to the development of hypertension following ETOH consumption. Methods: Male adult Wistar rats were subjected to the intake of increasing ETOH concentrations in their drinking water (first week: 5%, second week: 10%, third and fourth weeks: 20% v/v). Results: ETOH consumption decreased plasma and urinary volumes, as well as body weight and fluid intake. Furthermore, plasma osmolality, plasma sodium and urinary osmolality were elevated in the ETOH-treated rats. ETOH intake also induced a progressive increase in the mean arterial pressure (MAP), without affecting heart rate. Initially, this increasein MAP was correlated with increased plasma concentrations of adrenaline and noradrenaline. After the second week of ETOH treatment, plasma catecholamines returned to basal levels, and incremental increases were observed in plasma concentrations of vasopressin (AVP) and angiotensin II (ANG II). Conversely, plasma oxytocin, atrial natriuretic peptide, prolactin and the hypothalamus-pituitary-adrenal axis components were not significantly altered by ETOH. Conclusions: Taken together, these results suggest that increased sympathetic activity may contribute to the early increase in MAP observed inETOHtreated rats. However, the maintenance of this effect may be predominantly regulated by the long-term increase in the secretion of other circulating factors, such as AVP and ANG II, the secretion of both hormones being stimulated by the ETOH-induced dehydration. © The Author 2013. Medical Council on Alcohol and Oxford University Press. All rights reserved.

Ovulação de matrizes de pacu Piaractus mesopotamicus e o papel da prostaglandina F2α

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fertilização artificial de ovócitos de curimbatá, Prochilodus lineatus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeitos do treinamento físico sobre aspectos endócrino-metabólicos de ratos administrados com dexametasona

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Uso do sistema de cultivo bidimensional e tridimensional para diferenciação de células-tronco espermatogoniais e indução da espermatogênese in vitro em murinos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo clínico e molecular de pacientes com displasia septo-ótica ou deficiência hormonal hipofisária (gene HESX1 e PROP1)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relação entre os sinais clínicos neurológicos e os achados tomográficos de 20 cães com suspeita de neoplasia intracraniana

Pós-graduação em Medicina Veterinária - FMVZ

Comparação entre doses constantes e decrescentes de extrato de pituitária eqüina na indução de superovulacão em éguas

Pós-graduação em Medicina Veterinária - FMVZ