Acceleration of Sperm Transit Time and Reduction of Sperm Reserves in the Epididymis of Rats Exposed to Sibutramine

Sibutramine is a drug globally used for the treatment of obesity. The aim of this study was to investigate male reproductive disorders caused by sibutramine in adult rats. Wistar rats were treated for 28 consecutive days (gavage) with 10 mg/kg of sibutramine. Control animals received only vehicle (dimethylsulfoxide and saline). The rats were sacrificed for evaluation of body and reproductive organ weights, sperm parameters, hormone levels (luteinizing hormone, follicle-stimulating hormone, and testosterone), testicular and epididymal histopathology, sexual behavior, fertility and in vitro contractility of the epididymal duct. Sibutramine decreased (P < .05) weights of the epididymis and ventral prostate, but not of other reproductive organs. The sperm number and transit time in the epididymal cauda were decreased (P < .001), but the daily sperm production was not altered. Moreover, morphology and sperm motility, histopathology of the testes and epididymis, sexual behavior, fertility, and serum hormone levels were not altered by the treatment. Sibutramine increased the potency of norepinephrine and, per se, increased the mechanical activity of the epididymal duct in vitro. Thus, although sibutramine in these experimental conditions did not interfere with the reproductive process of rats, it provoked acceleration of the sperm transit time and a decrease in the sperm reserves in the epididymal cauda. This alteration is probably related to the sympathomimetic effect of this drug, as shown by the in vitro assays. In humans, use of this drug might present a threat for male fertility because sperm reserves in men are naturally lower than those in rats.

Fertility of rat epididymal sperm after chemically and surgically induced sympathectomy

Guanethidine, a chemical that selectively blocks sympathetic noradrenergic neurons, was used to investigate the role of sympathetic innervation in the fertility of rat epididymal sperm, using both natural mating and in utero insemination protocols. This animal model correlates, at least in part, with spinal cord injury (SCI) in men. Adult male rats were treated daily by i.p. injections, for 21 or 42 days, with 0 or 6.25 mg/kg guanethidine. To compare the effects of guanethidine-induced sympathectomy with those following surgically induced sympathectomy, the inferior mesenteric ganglion and the proximal hypogastric nerves were removed in another group of rats. Both chemically and surgically induced sympathectomy increased the weight of the epididymis and seminal vesicles/coagulating glands as well as the number and the transit time of cauda epididymal sperm. Neither serum testosterone levels nor LH was affected by treatment with guanethidine. Using natural mating, no litters were produced by guanethidine-treated rats. Chemically denervated rats failed to produce copulatory plugs or ejaculate into the uterus. However, distal cauda epididymal sperm from chemically or surgically denervated rats displayed normal fertilization ability (80%) using in utero inseminations. In addition, the sperm of denervated rats did not show abnormal sperm chromatin structure using an assay that detects DNA damage. We conclude that sympathectomy delays the transit of sperm through the cauda epididymidis and produces ejaculatory dysfunction but does not compromise sperm quality in the distal cauda epididymidis. Moreover, these data provide compelling evidence that there is no association between the prolonged transit time of sperm within the epididymis, i.e., pre-ejaculatory sperm aging, and the fertility of those sperm, which has important implications for artificial insemination using sperm from men with SCI.

Rat epididymal sperm quantity, quality, and transit time after guanethidine-induced sympathectomy

Guanethidine, a chemical that selectively abolishes peripheral noradrenergic nerves, was used to investigate the role of sympathetic innervation in the maintenance of epididymal sperm quantity and quality. Four groups of 10 adult male rats each were treated daily for 21 days, by i.p. injections, with either 0 (saline vehicle), 6.25, 12.5, or 25 mg/kg guanethidine. Norepinephrine content was reduced to undetectable levels in the cauda epididymidis in all guanethidine groups after 3 wk of treatment and was reduced to 7.4% of the control values after 1 wk of 6.25 mg/kg treatment. While body weight gain was significantly decreased at 12.5 and 25 mg/kg compared to that in controls, there was a significant increase in the weights of the seminal vesicles/coagulating glands in all treated groups. The number of homogenization-resistant spermatids per testis and the daily sperm production per testis remained unchanged. The weight of the epididymis was significantly increased at 6.25 and 12.5 mg/kg. Moreover, the number of cauda epididymal sperm and the transit time were increased significantly at 6.25 mg/kg (10.2 days) compared to values in the control cauda (6.3 days). Neither serum testosterone levels nor LH was affected in a dosage-related manner. There were no effects of guanethidine treatment on cauda epididymal sperm motility or morphology. A quantitative analysis of detergent-extracted cauda epididymal sperm proteins by SDS-PAGE revealed no differences, but there were diminutions in seven proteins in homogenates of caput/ corpus tissue. Histologic analysis of testis and epididymis sections revealed no differences between control and denervated animals. In a subsequent experiment the lowest effective dosage (6.25 mg/kg) was given to rats for 1 wk, and an increased number of cauda epididymal sperm and a delay in sperm transit were observed. Our results indicate that low-dosage guanethidine exposure denervates the epididymis within 1 wk, thereby delaying epididymal transit; however, neither 1- nor 3-wk exposure produces qualitative changes in the sperm.

Growth of free-floating aquatic macrophytes in different concentrations of nutrients

The objective of the study was to evaluate the effect of different concentrations of nitrogen and phosphorus on the growth of the free-floating aquatic macrophytes Eichhornia crassipes, Pistia stratiotes, and Salvinia molesta. The plants were cultured in 2,000-l outdoor concrete tanks. Triplicate tanks, with a continuous flow of effluent from culture ponds containing Nile tilapia, were used for each plant type (n = 3). The plant material was collected monthly from 0.25 m(2) floating quadrats, at the two ends of the tanks (higher nutrient concentrations near the inflow and lower nutrient concentrations near the outflow). In low nutrient concentrations, the maximum relative growth rates (RGRs) for E. crassipes (0.016/day) and P. stratiotes (0.016/day) were significantly lower (P <= 0.05) than for S. molesta (0.029/day). There were no significant differences between the RGRs of S. molesta in the different nutrient concentrations. Eichhornia crassipes and P. stratiotes had their growth limited by nitrogen and phosphorus concentrations. The increase in plant density during the experiment probably also affected the growth of these species. In this context, E. crassipes and P. stratiotes can cause problems in nutrient-rich waterbodies, but under these experimental conditions their growth was limited by nitrogen and/or phosphorus concentrations. The growth of S. molesta was not influenced by the different nutrient concentrations.

Effects of exercise training on the cardiovascular system: Pharmacological approaches

Physical exercise promotes beneficial health effects by preventing or reducing the deleterious effects of pathological conditions, such as arterial hypertension, coronary artery disease, atherosclerosis, diabetes mellitus, osteoporosis, Parkinson's disease, and Alzheimer disease. Human movement studies are becoming an emerging science in the epidemiological area and public health. A great number of studies have shown that exercise training, in general, reduces sympathetic activity and/or increases parasympathetic tonus either in human or laboratory animals. Alterations in autonomic nervous system have been correlated with reduction in heart rate (resting bradycardia) and blood pressure, either in normotensive or hypertensive subjects. However, the underlying mechanisms by which physical exercise produce bradycardia and reduces blood pressure has not been fully understood. Pharmacological studies have particularly contributed to the comprehension of the role of receptor and transduction signaling pathways on the heart and blood vessels in response to exercise training. This review summarizes and examines the data from studies using animal models and human to determine the effect of exercise training on the cardiovascular system. (c) 2007 Elsevier B.V. All rights reserved.

Autonomic control of cardiorespiratory interactions in fish, amphibians and reptiles

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

The unequal influences of the left and right vagi on the control of the heart and pulmonary artery in the rattlesnake, Crotalus durissus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The fate of copepod populations in the Paranapanema River (São Paulo, Brazil), downstream from the Jurumirim dam

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeitos agudos do tabagismo sobre a modulação autonômica: análise por meio do plot de poincaré

FUNDAMENTO: O tabagismo altera a função autonômica. OBJETIVO: Investigar os efeitos agudos do tabagismo sobre a modulação autonômica e a recuperação dos índices de variabilidade de frequência cardíaca (VFC) pós-fumo, por meio do plot de Poincaré e índices lineares. MÉTODOS: Foram avaliados 25 fumantes jovens, os quais tiveram a frequência cardíaca analisada, batimento a batimento, na posição sentada, após 8 horas de abstinência, por 30 minutos em repouso, 20 minutos durante o fumo e 30 minutos pós-fumo. Análise de variância para medidas repetidas, seguido do teste de Tukey, ou teste de Friedman seguido do teste de Dunn foram aplicados dependendo da normalidade dos dados, com p < 0,05. RESULTADOS: Durante o fumo, houve redução dos índices SD1 (23,4 ± 9,2 vs 13,8 ± 4,8), razão SD1/SD2 (0,31 ± 0,08 vs 0,2 ± 0,04), RMSSD (32,7 ± 13 vs 19,1 ± 6,8), SDNN (47,6 ± 14,8 vs 35,5 ± 8,4), HFnu (32,5 ± 11,6 vs 19 ± 8,1) e do intervalo RR (816,8 ± 89 vs 696,5 ± 76,3) em relação ao repouso, enquanto que aumentos do índice LFnu (67,5 ± 11,6 vs 81 ± 8,1) e da razão LF/HF (2,6 ± 1,7 vs 5,4 ± 3,1) foram observados. A análise visual do plot mostrou menor dispersão dos intervalos RR durante o fumo. Com exceção da razão SD1/SD2, os demais índices apresentaram recuperação dos valores, 30 minutos após o tabagismo. CONCLUSÃO: O tabagismo produziu agudamente modificações no controle autonômico, caracterizadas por ativação simpática e retirada vagal, com recuperação 30 minutos após o fumo.

Síndrome dolorosa complexa regional: epidemiologia, fisiopatologia, manifestações clínicas, testes diagnósticos e propostas terapêuticas

JUSTIFICATIVA E OBJETIVOS: A Síndrome Dolorosa Complexa Regional (SDCR), assim denominada a partir de 1994 pelo Consenso da Associação Internacional para o Estudo da Dor (AIED) e anteriormente denominada de várias formas, tais como Distrofia Simpático Reflexa, Causalgia, Algodistrofia ou Atrofia de Sudeck, é uma doença cuja compreensão dos limites clínicos, fisiopatologia e implicações de patogenia ainda é pobre. Disto resulta a enorme insatisfação não só para os pacientes como para os profissionais da saúde quanto aos métodos terapêuticos atualmente disponíveis. O objetivo deste trabalho é rever a literatura e atualizar um conjunto de informações com o intuito da melhor compreensão desta importante síndrome dolorosa. CONTEÚDO: Este é um trabalho de revisão da literatura nos diversos aspectos da SDCR, com ênfase em suas causas, definição e taxonomia, fisiopatologia, características clínicas, testes diagnósticos e propostas de tratamentos mais recentes. CONCLUSÕES: Poucos são os estudos controlados adequadamente, encobertos e aleatórios, publicados com grandes amostras, havendo muitas dúvidas sobre esta doença. Desta forma, ainda há enorme empirismo na sua terapêutica, e os resultados obtidos são insatisfatórios.

Complete atrioventricular block during renal transplantation in a patient with Alport's syndrome: case report

CONTEXTO: A síndrome de Alport é responsável por aproximadamente 5% dos pacientes com insuficiência renal crônica. Nessa doença, anormalidades no sistema de condução cardíaco são mais freqüentes que na população em geral. OBJETIVO: Relatar caso de síndrome de Alport que desenvolveu bloqueio atrioventricular total durante um transplante renal. RELATO DE CASO: Paciente masculino, 21 anos de idade, com insuficiência renal crônica secundária à síndrome de Alport, foi submetido a transplante renal sob anestesia peridural. Durante o procedimento anestésico-cirúrgico apresentou bloqueio atrioventricular total, que foi tratado rapidamente, e com sucesso, usando-se um marcapasso transcutâneo. O bloqueio simpático extenso pode contribuir para o desenvolvimento de distúrbios no sistema de condução cardíaco, particularmente em pacientes com insuficiência renal crônica em esquema de diálise. Mesmo em pacientes com eletrocardiograma pré-operatório normal e sem distúrbios de condução, graus variáveis de bloqueio atrioventricular, incluindo bloqueio atrioventricular total, podem ocorrer. Nesse caso, o uso de marcapasso transcutâneo é tratamento rápido e efetivo na sala de operação até o final da cirurgia, quando o tratamento definitivo pode ser planejado.

Replacement of dicalcium phosphate by rock phosphate in cattle diets: nutrients digestibility, plasma parameters, ruminal fermentation and microbial synthesis efficiency

Este estudo foi conduzido para avaliar os efeitos da substituição do fosfato bicálcico pelo fosfato de rocha na dieta de bovinos em crescimento. Foram determinados a digestibilidade aparente das dietas, a absorção aparente do fósforo, cálcio e flúor, o pH ruminal, a concentração de amônia ruminal, a eficiência microbiana e o fósforo no plasma utilizando-se cinco bovinos da raça Holandesa Preto-e-Branco, fistulados, pesando entre 275 e 283 kg. O delineamento estatístico foi um quadrado latino 5 × 5 e as dietas consistiram de 0, 25, 50, 75 e 100% de substituição do fosfato bicálcico pelo fosfato de rocha no suplemento mineral. A adição de fosfato de rocha nas dietas ocasionou aumento linear na ingestão, no fluxo omasal, no fluxo fecal e no desaparecimento total do flúor. As dietas não diferiram quanto à absorção aparente do cálcio, assim como em relação à ingestão, excreção, digestão e digestibilidades aparentes parcial e total da matéria seca, matéria orgânica, proteína bruta, fibra em detergente neutro e carboidratos não-fibrosos. O fósforo no plasma não foi influenciado pelos tratamentos e a média foi de 5,93 mg/dL. Não houve diferença para o pH ruminal e concentração de amônia ruminal. A substituição do fosfato bicálcico não afetou a síntese microbiana aparente e verdadeira de proteína. A total substituição do fosfato bicálcico pelo fosfato de rocha em suplementos minerais em bovinos em crescimento não afetou o ambiente ruminal e a síntese de proteína no rúmen. Assim, a substituição do fosfato bicálcico em dietas para bovinos em crescimento diminui a absorção de fósforo e deveria ser vista com cuidado dependendo dos requerimentos.

MORPHOMETRIC AND BIOCHEMICAL EVALUATION OF RAT PROSTATE AND SEMINAL-VESICLE FOLLOWING CHEMICAL SYMPATHECTOMY WITH GUANETHIDINE

Selective chemical sympathectomy of the internal genital organs of adult male rats was undertaken by chronic treatment with low doses of guanethidine. Biochemical and morphometric methods revealed that removal of sympathetic innervation prevents fructose secretion in the prostate and seminal vesicle, in addition to promoting reduced efficiency of delivery by the latter.

Partial urethral obstruction of rabbit urinary bladder: stereological evidence that the increase in muscle content is mostly driven by changes in number, rather than size, of smooth muscle cells

The effects of partial urethral obstruction on the detrusor muscle of rabbit urinary bladder were investigated using stereological sampling and estimation tools. Twelve female Norfolk rabbits (2.5-3.0 kg body weight) were divided into four groups: 3, 7 and 12 weeks after surgical intervention to produce a standard partial obstruction and unobstructed controls. Following removal, bladder axes (craniocaudal, dorsoventral and laterolateral) and organ weights were recorded. Bladders were prepared for light microscopy by multistage random sampling procedures. Stereological methods were used to estimate the volume of muscle and the packing density and total number of myocyte nuclei in each bladder. We also estimated mean myocyte volume and the mean cross-sectional area and length of myocytes. Group comparisons were made by one-way analysis of variance. Changes in bladder axes were mainly laterolateral and craniocaudal. Mean bladder weight increased roughly six-fold by 3 weeks and 17-fold by 12 weeks and was accompanied, on average, by 12- and 33-fold increases in total muscle volume. These variables did not differ at 3 and 7 weeks post-obstruction. Increases in muscle content were not accompanied by changes in packing densities but were associated with increases in the total numbers of myocyte nuclei (13-fold by 3 weeks, 28-fold by 12 weeks). Mean myocyte volume did not vary significantly between groups but cells in obstructed groups were shorter and wider. These findings support the notion that partial outflow obstruction leads to an increase in the number, but not mean volume, of myocytes. If due solely to myocyte mitosis, the total of 43 x 10(8) cells found at 12 weeks could be generated by the original complement of 15 x 10(7) cells if an average of only 2.1 x 10(6) new cells was produced every hour. In reality, even this modest proliferation rate is unlikely to be achieved because myocyte proliferation rates are very low and it is possible that new myocytes can arise by differentiation of mesenchymal or other precursor cells.

THE HYPOPHYSEAL-TESTICULAR AXIS AND SEX ACCESSORY-GLANDS FOLLOWING CHEMICAL SYMPATHECTOMY WITH GUANETHIDINE OF PRE-PUBERTAL TO MATURE RATS

Selective chemical sympathectomy of the internal sex organs of prepubertal to mature male Wistar rats was performed by chronic treatment with low doses of guanethidine. Plasma testosterone and luteinizing hormone and the intratesticular level of testosterone were determined. The weight and fructose content of seminal vesicle and ventral prostate were also investigated. The results showed that sympathetic innervation is related to the control of the hypophyseal-testicular axis as well as to the growth and potential secretory activity of the male sex accessory glands.