New approach for reproductive toxicity assessment: chromatoid bodies as a target for methylmercury and polychlorinated biphenyls in prepubertal male rats

This study investigated the reproductive toxicity of methylmercury (MeHg) and Aroclor (Sigma-Aldrich), alone or in combination, following exposure of prepubertal male rats considering the chromatoid body (CB) as a potential target. The CB is an important molecular regulator of mammalian spermatogenesis, primarily during spermatid cytodifferentiation. Male Wistar rats were exposed to MeHg and/or Aroclor , according the following experimental design: control group, which was administered in corn oil (vehicle) only; MeHg-treated group, which was administered 0.5mg kg-1 day-1 MeHg; Aroclor-treated group, which was administered 1mg kg-1 day-1 Aroclor; Mix-LD, group which was administered a low-dose mixture of MeHg (0.05mg kg-1 day-1) and Aroclor (0.1mg kg-1 day-1); and Mix-HD group, which was administered a high-dose mixture of MeHg (0.5mg kg-1 day-1) and Aroclor (1.0mg kg-1 day-1). MeHg was diluted in distilled water and Aroclor was made up in corn oil (volume 1mL kg-1). Rats were administered the different treatments from PND23 to PND53 by gavage, . The morphophysiology of CBs was analysed, together with aspects of steroid hormones status and regulation, just after the last treatment on PND53. In addition, the long-term effects on sperm parameters were assessed in adult animals. MeHg exposure increased mouse VASA homologue (MVH) protein levels in seminiferous tubules, possibly affecting the epigenetic status of germ cells. Aroclor produced morphological changes to CB assembly, which may explain the observed morphological defects to the sperm flagellum and the consequent decrease in sperm motility. There were no clear additive or synergistic effects between MeHg and Aroclor when administered in combination. In conclusion, this study demonstrates that MeHg and Aroclor have independent deleterious effects on the developing testis, causing molecular and morphological changes in CBs. To the best of our knowledge, this is the first study to show that CBs are targets for toxic agents.

Short-term effects of green tea chronotherapy on the metabolic homeostasis of mice on different diets

Biological rhythms can be defined as changes in physiological or behavioral variables that repeat at certain time intervals. Rhythms that last approximately 24 h are referred to as circadian rhythms. Modern lifestyles have drastically affected human habits, as well as the population's eating habits. These changes have generated an epidemic of metabolic syndromes, such as obesity and diabetes. In an attempt to combat obesity, populations have attempted to use many different herbal remedies and plant-based drugs, the most common of which is Camellia sinensis, or green tea. Most of the studies on the effects of C. sinensis on maintaining body weight have reported the involvement of this substance in lipid oxidation. The objective of this study was to evaluate how the administration of C. sinensis at different times of day influenced changes in body weight, blood glucose levels, and food intake of mice kept under different diet conditions. The structural organization of abdominal adipose tissue was also evaluated, as were certain aspects of lipid metabolism and overall synthetic activity in the liver, adipose tissue, and ovaries. The results obtained suggest that the intake of green tea in the light phase of the day stimulates weight loss, regardless of the diet ingested. Neither glucose levels nor the structural organization of adipose tissue was found to be altered in any of the experimental groups. Neither diet nor the time at which the green tea was administered was found to have any effects on the amount of food the mice consumed. The time at which green tea was consumed and the type of diet both influenced LXRαβ nuclear receptor expression, as well as the expression of fibrillarin in the liver and ovaries, although this influence was tissue specific.

Characterization of Mongolian gerbil chromatoid bodies and their correlation with nucleolar cycle during spermatogenesis

The aims of the present study were to monitor the nucleolar cycle in Mongolian gerbil spermiogenesis, to verify the relationship between the nucleolar component and chromatoid body (CB) formation and to investigate the function of this cytoplasmic supramolecular structure in spermatogenic cells. Histological sections of adult seminiferous tubules were analysed cytochemically by light microscopy and ultrastructurally by transmission electron microscopy. The results reveal that in early spermatids, the CB was visualized in association with Golgi vesicles indicating that this structure may participate in the acrosome formation process as had been reported in other rodents. In late spermatids, the CB was observed near the axoneme region suggesting that this structure may support spermatozoon tail formation as happens in other species. Chromatoid body was joined with lipid droplets in this same cell type. This observation should be investigated to verify whether CB may be related to steroidal hormone metabolism. In conclusion, our data showed that there is disintegration of primary spermatocyte nucleoli at the beginning of prophase I and a fraction of this nucleolar material migrates to the cytoplasm, where a specific structure is formed, known as the 'chromatoid body', which apparently participates in some parts of the gerbil spermiogenesis process.