Bisphenol A (BPA), a well-known endocrine disruptor, is metabolized and eliminated rapidly from the body in adult animals. However, many authors have reported that perinatal BPA exposure alters development of the brain, reproductive system and behavior in the next generation. Recently, BPA substitutes, especially bisphenol F (BPF), have been used because of concerns about the influence of BPA on children, although the actual effects on the next generation are unknown. In this study, we observed behavioral adverse effects of the offspring of mice exposed to BPA or BPF in fetal period. Female C57BL/6 mice were given oral BPA or BPF (0 or 10 mg/kg body weight) daily from gestational day 11.5 to 18.5. The open field test, the elevated plus maze test and the forced swim test were performed at postnatal week 10. BPF exposure altered offspring behavior significantly, resulting in increases in anxiety and depressive state. The influence of BPF was stronger than that of BPA. We demonstrated novel evidence that BPF influences the behavior of offspring.

Bisphenol A (BPA) is among the better-known endocrine disruptors. BPA is used in various food-contacting materials and is easily eluted into food; as a result, we are exposed to BPA on a daily basis. In adults, BPA is metabolized and eliminated rapidly from the body. However, numerous reports suggest that fetuses and young children are susceptible to BPA. One of the concerning adverse effects of BPA is disruption of behavior, especially anxiety-like behavior. In order to study the mechanism of influences on offspring, it is important to clarify the most vulnerable gestation period. We hypothesized that offspring in late pregnancy would be more susceptible to BPA, because late pregnancy is a critical time for functional brain development. In this study, C57BL/6 mouse fetuses were exposed prenatally by oral dosing of pregnant dams, once daily from gestational day 5.5 to 12.5 (early pregnancy) or 11.5 to 18.5 (late pregnancy), with BPA (0 or 10 mg/kg body weight). Following birth and weaning, the resulting pups were tested using an elevated plus maze at postnatal week 10. The behavior of the offspring was altered by prenatal BPA exposure during late pregnancy but not during early pregnancy. These results indicated that offspring are more vulnerable to exposure to BPA in late pregnancy.

The bone is a dynamic and metabolically active organ in which growth and resorption of the osteochondral matrix is orchestrated by osteoblasts and osteoclasts. For decalcified paraffin-embedded specimens, decalcifying agents alter the staining intensity, and excess decalcification interferes with bone staining.Robust bone staining methods independent of the decalcification conditions and animal species are lacking.In this study, we have developed a novel polychrome staining method, named JFRL staining, which stains the components of osteochondral tissue in different colors. With this staining we could visualize the hyaline cartilage as blue by alcian blue, osteoid as red by picrosirius red, and mineralized bone as green by picro-light green SF or picro-naphthol green B and easily distinguished osteoblasts, osteocytes, and osteoclasts. In mineralized bone, this staining revealed the obvious lamellar structures and woven bone.Notably, this staining was independent of the decalcification conditions and experimental animal species examined. To verify the usefulness of JFRL staining, we observed cotton rat tail which has shorter length and shows a false autotomy. The caudal vertebrae were normally developed via endochondral ossification without a fracture plane. At 6 months of age, the number of chondrocytes declined and the hypertrophic zone was absent at the epiphyseal plate, which might reflect the shorter tail. In conclusion, JFRL staining is the first method to simultaneously distinguish osteochondral matrix and bone cells in one section regardless of decalcifying conditions. This robust staining will provide new information for a wide number of biomedical fields, including bone development, physiology, and pathology.

Normal-pressure hydrocephalus (NPH) is a condition in which the ventricle is enlarged without elevated cerebrospinal fluid pressure, and it generally develops in later life and progresses slowly. A complete animal model that mimics human idiopathic NPH has not yet been established, and the onset mechanisms and detailed pathomechanisms of NPH are not fully understood. Here, we demonstrate a high spontaneous prevalence (34.6%) of hydrocephalus without clinical symptoms in inbred cotton rats (Sigmodon hispidus). In all 46 hydrocephalic cotton rats, the severity was mild or moderate and not severe. The dilation was limited to the lateral ventricles, and none of the hemorrhage, ventriculitis, meningitis, or tumor formation was found in hydrocephalic cotton rats. These findings indicate that the type of hydrocephalus in cotton rats is similar to that of communicating idiopathic NPH. Histopathological examinations revealed that the inner granular and pyramidal layers (layers IV and V) of the neocortex became thinner in hydrocephalic brains. A small number of pyramidal cells were positive for Fluoro-Jade C (a degenerating neuron marker) and ionized calcium-binding adaptor molecule 1 (Iba1)-immunoreactive microglia were in contact with the degenerating neurons in the hydrocephalic neocortex, suggesting that hydrocephalic cotton rats are more or less impaired projections from the neocortex. This study highlights cotton rats as a candidate for novel models to elucidate the pathomechanism of idiopathic NPH. Additionally, cotton rats have some noticeable systemic pathological phenotypes, such as chronic kidney disease and metabolic disorders. Thus, this model might also be useful for researching the comorbidities of NPH to other diseases.