Estudo morfológico da sínfise púbica de ratos e camundongos durante a gravidez / Morphological study of rats and mice pubic symphysis during pregnancy

O objetivo desse estudo foi avaliar as diferenças existentes na sínfise púbica de camundongos e ratos fêmeas, grávidas e não grávidas, descrevendo as alterações morfológicas ocorridas na articulação com a finalidade de entender os movimentos apresentados pela articulação ao longo da gestação. Para tal, as sínfises foram coletadas de camundongos fêmeas grávidas no 6º, 12º e 18º dias de gestação, e nas ratas com 18 dias de gestação. Foram fixadas em paraformoldeído e a seguir descalcificadas em solução de Morse. Na sequência, as peças foram incluídas em parafina. Cortes de 7 micrômetros foram realizados e corados em Picrosirius e Resorcina-Fucsina. A coloração com Picrosirius evidenciou em camundongos fêmeas virgens a presença de fibras grossas de colágeno diferente dos outros grupos de camundongos, os quais apresentaram fibras finas. A análise de fibras elásticas mostrou que, com o decorrer da gestação, estas aumentam em espessura e número. Em ratas com 18 dias de gestação foi observado o aparecimento de tecido conjuntivo fibroso no disco de cartilagem hialina, aumentando assim, o espaço inter-púbico e modificando a estrutura de sincondrose encontrada nos animais virgens. Observou-se também aumento no diâmetro e quantidade de fibras elásticas em relação às ratas virgens. Podemos concluir que a articulação de camundongos fêmeas grávidas passam por transformações estruturais qualitativas e quantitativas ao longo da gravidez. Em ratas prenhas, além do aumento de fibras elásticas e da distância entre os ossos do quadril, a articulação diferenciou-se pelo aparecimento de tecido conjuntivo fibroso para facilitar o parto.

The objective of this study was to assess the existing differences in the pubic symphysis of female rats and mice, pregnant and non pregnant, describing the morphological alterations occurred in the joint and understanding the movements shown during pregnancy. The pubic symphysis were collected from female pregnant mice on the 6th, 12th and 18th days of pregnancy, and from rats with 18 days of pregnancy. They were fixed in paraformoldehyde and following decalcificated with Morse’s solution. The samples were then, included in paraffin. Seven micrometers slices were made and stained with Picrosirius and Resorcin-Fuchsin. The Picrosirius staining had shown, in virgin female mice, the presence of thick collagen fibers different from the other groups of mice, which presented thin fibers. The analysis of elastic fibers showed that, with the progress of pregnancy there is an increase in their thickness and number. In rats with 18 days of pregnancy, an appearance of fibrous conjunctive tissue on the hyaline cartilage disc was observed, enlarging the inter-pubic space and modifying the synchondrosis structure found in the virgin animals. It was also observed an increase in diameter and amount of elastic fibers comparing to virgin rats. We conclude that the pregnant female mice’s joint undergoes transformations in structure, quality and amount during the pregnancy. In pregnant rats, besides the increase of elastic fibers and the distance between the hip’s bone, the joint had differred by the appearance of fibrous conjunctive tissue, thus making the birth easier.

A study of the myotoxicity of bothropstoxin-i using manganese in mouse phrenic nerve-diaohragm and extensor digitorum longus preparations

Bothropstoxin-I (BthTX-I) from Bothrops jararacussu snake venom has a predominantly postsynaptic action that is responsible for this toxin´s myotoxicity. However, BthTX-I also has a presynaptic action that is counteracted by Mn2+, a reversible neuromuscular blocker that acts predominantly presynaptically. In this work, we used two nerve-muscle preparations (mouse phrenic nerve-diaphragm - PND and extensor digitorum longus - EDL) to investigate the ability of Mn2+ to protect against the myotoxicity of BthTX-I. The preparations were incubated with Tyrode solution (control), BthTX-I, or Mn2+ alone. BthTX-I (1.4 µM) produced irreversible blockade in both preparations, whereas the blockade by Mn2+ (0.9 mM) was total and reversible in PND but just partially reversible in EDL. Pretreating the preparations with Mn2+ resulted in 100% and 80% protection against BthTX-I-induced blockade, respectively. However, when Mn2+ (0.9 or 1.8 mM) and BthTX-I (1.4 µM) were co-incubated for 30 min before testing, the blockade was faster and sustained. Washing the preparations resulted in complete, sustained recovery in those exposed to 1.8 mM Mn2+ but not to 0.9 mM Mn2+. Morphological analysis showed that the extent of fiber damage by BthTXI (1.4 µM) was 82% (PND) and 68.5% (EDL), and that Mn2+ (0.9 mM) afforded 40% protection in both preparations and reduced the increase in muscle fiber cross-sectional area by 20% and 15%, respectively, compared to BthTX-I alone. Mn2+ (0.9 mM) significantly attenuated the release of creatine kinase by BthTXI. The low creatine kinase activity resulted from a protective action of Mn2+ on the sarcolemma and from direct inactivation of the released enzyme. These results show that Mn2+ prevents membrane disruption by BthTX-I and can protect against the myotoxicity and neurotoxicity caused by this toxin.