Aspects of the macro and microscopic anatomy of the sciatic nerve in Wistar rats / Aspectos de la anatomía macro y microscópica del nervio ciático en ratas Wistar

The present study seeks to systematize morphological and morphometrical parameters and brings new data on the main branch of the lumbosacral plexus ­ i.e., sciatic nerve ­ in Wistar rats aged four and seven weeks. Sixteen female were divided into two groups, namely animals aged four weeks, and animals aged seven weeks. The specimens were studied at proximal and distal segments of the right hind limb sciatic nerves. Semi-thin transverse sections (0.25 µm thickness) were stained with 1 % toluidine blue, and the morphometric analysis was processed through the KS 400 software. Except for the number of fascicles and fascicular diameter, no differences were found between the proximal and distal segments. We observed differences when morphometric values were compared between 4- and 7- week old animals, with some exceptions (number of fascicles and myelinated fibers, and capillary area and number). The macroscopic data disagree with a previous description of the sciatic nerve being composed by two fascicles. Instead, sciatic nerve's only fascicle trifurcates or quadrifurcates at the distal third of the thigh. The total capillary area and density were calculated, and these are the first referential data for the sciatic nerve. Histograms of myelinated fiber and axons considering the animal ages were built. The results presented here are important because experimental studies, mainly studies on nerve regenerations require comparison with normal reliable data.

El objetivo fue sistematizar los parámetros morfológicos y morfométricos y traer nuevos datos sobre el ramo principal del plexo lumbosacro - es decir nervio ciático - en ratas Wistar de 4 a 7 semanas. Dieciséis ratas fueron divididas en dos grupos, con 4 y 7 semanas de edad. Las muestras estudiadas fueron los segmentos proximal y distal del nervio ciático derecho. Secciones delgadas (espesor 0,25 mm) fueron teñidas con azul de toluidina al 1 % y el análisis morfométrico se llevó a cabo utilizando el programa KS 400. Excepto para el número de fascículos y diámetro fascicular, no se encontraron diferencias entre los segmentos proximal y distal. Fueron observadas diferencias cuando se compararon los valores morfométricos entre animales de 4 y 7 semanas, con algunas excepciones (número de fascículos y fibras mielinizadas, área y número de capilares). Los datos macroscópicos no están de acuerdo con la descripción anterior del nervio ciático siendo compuesto por dos fascículos. En cambio, sólo trifurcación o cuadrifurcación fueron encontrados en el tercio distal del muslo. El área total capilar y la densidad fueron calculadas y estos constituyen los primeros datos de referencia para el nervio ciático. Se construyeron histogramas de fibras mielínicas y axones, teniendo en cuenta las edades de los animales. Los resultados presentados aquí son importantes porque los estudios experimentales, en especial aquellos sobre la regeneración nerviosa, requieren comparación con datos confiables normales.

Urethral dysfunction due to alloxan-induced diabetes. Urodynamic and morphological evaluation

PURPOSE: To evaluate the effect of short and long term alloxan-induced diabetes on bladder and urethral function of female rats, and also describing its correlated morphological alterations. METHODS: Thirty five female rats were divided into three groups: G1 (n=9), control group; G2 (n=17), six weeks alloxan-induced diabetic rats; G3 (n=9), 20 weeks alloxan-induced diabetic rats. Functional evaluation was performed by cystometry and simultaneous measurements of the urethral pressure during bladder filling and voiding. Morphological evaluation was also performed with measurement of bladder and urethral fibrosis and collagen content and thickness of lamina propria and smooth muscle layers. RESULTS: The peak bladder pressures and contraction amplitudes were decreased in 100% and 47% of the G3 and G2 groups respectively, when compared to control. Bladder overactivity was observed in 53% of the G2 group. CONCLUSION: Alloxan-induced diabetes urethropathty in female rat was associated to bladder morphological alterations as higher thicknesses of it lamina propria, detrusor and adventicea. .

Comparison of two experimental models of urodynamic evaluation in female rats / Comparação de dois modelos experimentais para avaliação urodinâmica em ratas

PURPOSE: Urodynamic studies in small animals can be performed through urethral sounding or cystostomy. OBJECTIVE: To compare the two methods of urodynamic evaluation in female rats. METHODS: Ten female rats weighing on average 250g, under anesthesia with urethane (1,25 mg/kg) were submitted in three repeats to an urethal catheter of 0,64 mm in external diameter for cystometric measurements of vesicle pressure(VP1) and contraction time (CT1). The catheter was extracted at a constant velocity of 0.05 cm/minute until complete exteriorization and determinations of maximal urethral pressure (UP1) and functional urethral length (FUL1). This was followed by a cystostomy with catheter PE50 and a new determination of the vesical pressure (VP2). After bladder denervation, a new cystometric record indirectly infered the maximum urethral closure pressure (UP2). The peak urethal pressure (UP3) and the functional urethral length (FUL2) were determined in another urethral sounding. The pressure registration system consisted of a continuous infusion pump regulated to a flow of 0.1 ml/minute connected both to the cystostomy catheter (PE-50) or the urethal catheter (0.64mm) and the polygraph Narco-Biosystem. Statistical analysis employed the Wilcoxon non-parametric test RESULTS: Mean VP1= 48,2 mmHg (11,8 SD); Mean VP2 = 38,2 mmHg (9,0 SD) "p" (VP1 X VP2) = 0,0039. Mean CT1=30,2 s (21,5 SD); Mean CT2=20,0 s(7 SD) p (CT1 X CT2) = 1,28. Mean UP1 = 47,2 mmHg (6,5 SD); Mean UP2 = 21,3 mmHg (6,6 SD), mean UP3 = 40,7 mmHg(13,3 SD) p (UP1 X UP2) = 0,002; "p" (UP1 X UP3) = 0,084; p (UP2 X UP3) = 0,002. Mean FUL1=14,2 mm (1,9 SD); Mean FUL2= 14,1mm (1,9 SD); p (FUL1 X FUL2) = 0,64. CONCLUSIONS: The methods employed to evaluate vesical and urethral pressures are different. The presence of the urethral catheter may be an obstructive factor. Surgical denervation up to the bladder neck level does not compromise urethral function.

INTRODUÇÃO: O estudo urodinâmico em ratas pode ser realizado através de sondagem vesical por via uretral ou por cistostomia. O objetivo deste estudo foi comparar estes dois métodos. MÉTODOS: Foram utilizadas 10 ratas da raça Wistar, peso médio de 250 gramas, anestesiadas com uretana (1,25 mg/kg). Inicialmente foi realizado estudo por sonda uretral (0,64 mm de diâmetro externo) para determinação da pressão vesical (PV1) e tempo de contração (TC1), após isto a sonda foi tracionada a velocidade constante (0,05 cm/m) até sua exteriorização pelo meato uretral, avaliando-se a pressão uretral máxima (PU1) e o comprimento funcional uretral (CFU1). Fez-se, então, a cistostomia (sonda PE50) para determinação da pressão vesical (PV2). A seguir, realizou-se desnervação cirúrgica da bexiga e realizou-se novo registro cistométrico para se inferir a pressão uretral indireta (PU2). Logo após, foi passada sonda uretral para determinação da pressão uretral máxima (PU3) e do comprimento funcional uretral (CFU2). O sistema de registro das pressões foi constituído de uma bomba de infusão contínua regulada para 0,1 ml/minuto conectada em Y com o cateter de cistostomia (PE-50) ou cateter uretral (0,64mm) a um polígrafo Narco-Bioystem. A análise estatística foi realizada através do método não paramétrico de Wilcoxon. RESULTADOS: Média PV1= 48,2 mmHg (11,8 SD); Média PV2 = 38,2 mmHg (9,0 SD). "p" (PV1 X PV2) = 0,0039. Média TC1=30,2 s (21,5 SD); Média TC2=20,0 (7 SD) p (TC1 X TC2) = 1,28. Média PU1 = 47,2 (6,5 SD); Média PU2 = 21,3 mmHg (6,6 SD), média PU3 = 40,7(13,3 SD) p (PU1 X PU2) = 0,002; "p" (PU1 X PU3) = 0,084; p (PU2 X PU3) = 0,002. Média CFU1=14,2 (1,9 SD); Média CFU2= 14,1 (1,9 SD); p (CFU1 X CFU2) = 0,64. CONCLUSÃO: Os métodos de avaliação urodinâmica são diferentes. A presença do cateter na uretra pode ser um fator obstrutivo. A desnervação cirúrgica, até o nível do colo vesical, não compromete a função uretral.