Study of corpus callosum in experimental hydrocephalic wistar rats

The association of Edaravone with shunt surgery improves behavioral performance, reduces astrocyte reaction and apoptosis, and promotes neuroprotection in young hydrocephalic rats

The neuroprotective effect of Edaravone in young hydrocephalic rats associated with a CSF derivation system was evaluated. The drug has already been shown to be beneficial in experimental hydrocephalus, but the combination of this drug with shunt surgery has not yet been investigated. Fifty-seven-day-old Wistar rats submitted to hydrocephalus by injection of kaolin in the cisterna magna were used and divided into five groups: control (n = 10), hydrocephalic (n = 10), hydrocephalic treated with Edaravone (20 mg/kg/day) (n = 10), hydrocephalic treated with shunt (n = 10) and hydrocephalic treated with shunt and Edaravone (n = 10). Administration of the Edaravone was started 24 h after hydrocephalus induction (P1) and continued until the experimental endpoint (P21). The CSF shunt surgery was performed seven days after hydrocephalus induction (P7). Open-field tests, histological evaluation by hematoxylin and eosin, immunohistochemistry by Caspase-3 and GFAP, and ELISA biochemistry by GFAP were performed. Edaravone reduced reactive astrogliosis in the corpus callosum and germinal matrix (p < 0.05). When used alone or associated with CSF shunt surgery, the drug decreased the cell death process (p < 0.0001) and improved the morphological aspect of the astroglia (p < 0.05). The results showed that Edaravone associated with CSF bypass surgery promotes neuroprotection in young hydrocephalic rats by reducing reactive astrogliosis and decreasing cell death.

Evaluation of the effects of quercetin on brain lesions secondary to experimental hydrocephalus in rats

INTRODUCTION

Hydrocephaly is a disease that affects not only the dynamics of the cerebrospinal fluid, but also other structures of the central nervous system. Although shunt is effective in reducing ventriculomegaly, many neurological damages are not reversed with surgery. Several studies demonstrate that oxidative stress is involved in the genesis of hydrocephalus lesions.

OBJECTIVE

Evaluate the neuroprotective response of quercetin in hydrocephalus.

MATERIALS AND METHODS

Male newborns rats were used, which received the 15% kaolin injection in the cisterna magna for induction of hydrocephalus. They were divided into control group (C), untreated hydrocephalic (HN), shunted hydrocephalic (HD), hydrocephalic treated with distilled water (HA), hydrocephalic treated with distilled water and shunt (HDA), hydrocephalic treated with quercetin peritoneal (HQp), hydrocephalic treated with quercetin peritoneal and shunt (HDQp), hydrocephalic treated with quercetin by gavage (HQg), and hydrocephalus treated with quercetin by gavage and shunt (HDQg).

RESULTS

Quercetin significantly improved the immunohistochemical markers, mainly caspase and GFAP. There were no significant changes in clinical/behavioral assessment. The use of isolated quercetin does not alter the volume and ventricular size, and the realization of ventriculo-subcutaneous shunt in newborn rats with hydrocephalus presents a high morbi-mortality.

CONCLUSION

The use of quercetin shows laboratory improvement of the effects of glial lesion and corpus callosum fibers and is therefore not justified by the use of the routine substance as neuroprotective.

Environmental enrichment reduces brain damage in hydrocephalic immature rats

PURPOSE

We investigate the effects of environmental enrichment (EE) on morphological alterations in different brain structures of pup rats submitted to hydrocephalus condition.

METHODS

Hydrocephalus was induced in 7-day-old pup rats by injection of 20% kaolin into the cisterna magna. Ventricular dilatation and magnetization transfer to analyze myelin were assessed by magnetic resonance. Hydrocephalic and control rats exposed to EE (n = 10 per group) were housed in cages with a tunnel, ramp, and colored plastic balls that would emit sound when touched. The walls of the housing were decorated with colored adhesive tape. Moreover, tactile and auditory stimulation was performed daily throughout the experiment. Hydrocephalic and control rats not exposed to EE (n = 10 per group) were allocated singly in standard cages. All animals were weighed daily and exposed to open-field conditions every 2 days until the end of the experiment when they were sacrificed and the brains removed for histology and immunohistochemistry. Solochrome cyanine staining was performed to assess the thickness of the corpus callosum. The glial fibrillary acidic protein method was used to evaluate reactive astrocytes, and the Ki67 method to assess cellular proliferation in the subventricular zone.

RESULTS

The hydrocephalic animals exposed to EE showed better performance in Open Field tests (p < 0.05), while presenting lower weight gain. In addition, these animals showed better myelination as revealed by magnetization transfer (p < 0.05). Finally, the EE group showed a reduction in reactive astrocytes by means of glial fibrillary acidic protein immunostaining and preservation of the proliferation potential of progenitor cells.

CONCLUSION

The results suggest that EE can protect the developing brain against damaging effects caused by hydrocephalus.

Camellia sinensis neuroprotective role in experimentally induced hydrocephalus in Wistar rats

PURPOSE

This study tested possible neuroprotective effects of Camellia sinensis-extracted polyphenols in experimental hydrocephalus in young rats.

METHODS

Seven-day-old Wistar rats were used in this study. Pups were subjected to hydrocephalus induction by 20 % kaolin intracisternal injection. The polyphenol was administered intraperitoneally for 9 or 20 days from the induction of hydrocephalus. Clinical observations and behavioral tests were performed once a day. The animals, deeply anesthetized, were sacrificed by cardiac perfusion with saline 10 or 21 days after induction of hydrocephalus and their brains were removed. Preparations were made for histological analysis by hematoxylin and eosin, solochrome-cyanine, and immunohistochemistry for GFAP.

RESULTS

Histopathological analysis showed that animals treated with the polyphenol for 9 consecutive days displayed reduction on astrocyte activity on the corpus callosum and external capsule, shown by GFAP immunostaining. They also displayed thicker and myelinated corpus callosum, exhibiting a more intense solochrome-cyanine blue staining.

CONCLUSION

Although these results demonstrate a possible neuroprotective effect at the initial onset of the disease, additional studies should be performed to obtain an effective and safe therapy for deeper studies in clinical trials.

Changes caused by hydrocephalus, induced by kaolin, in the corpus callosum of adult dogs

PURPOSE

To analyze the ventricular enlargement and myelination of the corpus callosum in adult dogs after four and eight weeks of kaolin-induction of hydrocephalus.

METHODS

36 dogs were randomly divided into 3 groups: 1 - without hydrocephalus, 2 - kaolin-induction of hydrocephalus until the fourth week, and 3 - kaolin-induction of hydrocephalus until the eighth week. Ventricular ratios and volumes were calculated using magnetic resonance images, and myelination of the corpus callosum were histologically evaluated using solocromo-cianin stain.

RESULTS

Radiological hydrocephalus was observed in 93.75% and overall mortality was 38.4%. Ventricular volumes and ratios were higher in groups 2 and 3 compared to group 1 and similar when measures in the fourth and eighth weeks were compared in the group 3. Indices of luminescence in the knee and in the splenium of the corpus callosum were higher in group 2 than in group 1 indicating that there was loss of myelin in group 2, and similar in groups 1 and 3, showing a tendency to remyelination after 8 weeks.

CONCLUSION

The corpus callosum of dogs with kaolin-induced hydrocephalus responds with demyelination of the knee and splenium by the fourth week with a tendency to remyelination by the eighth week.

Morphological and morphometric analysis of the hippocampus in Wistar rats with experimental hydrocephalus

BACKGROUND

The present study aims at better establishing the alterations caused by the usual enlargement of brain ventricles in this structure.

METHODS

Hydrocephalus was induced in 7-day-old Wistar rats by the injection of kaolin into the cisterna magna. Morphological studies were performed on the hippocampus 7, 14 and 21 days after injection. The total number of neurons in each hippocampus subarea as well as that of pyknotic neurons were counted. Then we calculated the pyknotic index (PI) by hippocampal subarea, taking into account the level of ventricular dilatation and time of induction of hydrocephalus.

RESULTS

PI was statistically larger in the CA1 subarea of the experimental group after 1 week of hydrocephalus induction as compared to the corresponding control as well as in animals that had developed mild hydrocephalus in groups G1, G2 and G3.

CONCLUSION

Hydrocephalus caused morphological alterations in the hippocampus, leading to important changes in its shape.

Maldevelopment of the cerebral cortex in the surgically induced model of myelomeningocele: implications for fetal neurosurgery

PURPOSE

The purpose of this study is to describe the malformations of cortical development detected in a model of cerebrospinal fluid (CSF) leakage and the influence of surgical closure technique on developmental outcome.

METHODS

Using a surgically induced model of myelomeningocele (MMC) in sheep, we studied the effects of different repair methods upon the development of hydrocephalus, the presence of the Arnold-Chiari II (AC-II) hindbrain malformation, and cerebral cortex developmental anomalies using gross and histologic (hematoxylin and eosin and Nissl staining) study techniques.

RESULTS

A malformed cerebral cortex, including 2 anomalous cortical folding patterns, and lower brain weights were observed in the untreated animals. Hydrocephalus and AC-II malformations were also found in this group. These malformations were mostly prevented with prenatal 2-layer closure.

CONCLUSIONS

Cerebral cortical malformations and hydrocephalus, in addition to the AC-II hindbrain malformation, are disorders caused by fetal CSF leakage. These malformations were prevented with the technique of MMC closure currently used in humans. Both observations magnify the importance of the second hit associated with chronic CSF leakage, in addition to the primary defect causing the MMC, in the development of the malformation complex.

Morphometric analysis of the optic nerve in experimental hydrocephalus-induced rats

PURPOSE

It was the aim of this study to investigate changes caused to the optic nerve of rats submitted to experimental hydrocephalus through morphometric analysis.

METHOD

At postnatal day 7, the rats underwent injection of kaolin into the cisterna magna, were sacrificed at postnatal day 14, 21 or 28, and the right optic nerves were dissected. We analyzed the area, minor diameter, densities of oligodendrocytes and astrocytes, total and damaged fibers as well as the relationship between damaged and total fibers.

RESULTS

At postnatal day 14, there was a reduction in the density of astrocytes and damaged fibers when compared to the controls. At postnatal day 21, the area and the minor diameter were reduced compared to the controls, and the densities of oligodendrocytes and damaged fibers were increased compared to the controls. At postnatal day 28, there was a reduction in the area and the minor diameter and an increase in the densities of oligodendrocytes, astrocytes and damaged fibers when compared to controls.

CONCLUSION

The optic nerve of rats submitted to experimental hydrocephalus suffers morphometric changes.

Single nucleotide polymorphisms of the pregnane x receptor gene in Han Chinese and a comparison with other ethnic populations

The pregnane X receptor (PXR/NR1I2) gene is a master regulator for a number of cytochrome P450s (CYPs) and drug transporters. This study aimed to detect the single nucleotide polymorphisms (SNPs) of the PXR gene in Han Chinese (n = 186) and to compare the frequencies of polymorphisms of the PXR gene with those in Caucasian and African Americans reported in the literature. The SNPs of the PXR gene were analyzed using the polymerase chain reaction (PCR) and direct sequencing analysis. The mutant frequencies of A11156C and T11193C in Han Chinese were 55% (95% confidence interval (CI): 0.49-0.61) and 59% (95% CI: 0.52-0.64), respectively, higher than those of Caucasian Americans (16 and 16%, respectively) and African Americans (33 and 30%, respectively). However, the reported SNPs in exons 2 and 4 (PXR*2,*3,*4,*6,*9,*10,and *11) were not detected in Han Chinese. These results indicate that there are marked differences in the mutant frequencies of A11156C and T11193C of PXR between Han Chinese and other ethnic groups. The mutant frequency in the coding region (exons 2 and 4) of PXR was very low in Han Chinese. Further studies are needed to determine the impact of common SNPs of PXR in Han Chinese and other ethnic populations on the phenotypic activity of cytochrome P450s and drug transporters transactivated by PXR.

Ultrastructural study of the lateral ventricle choroid plexus in experimental hydrocephalus in Wistar rats

Hydrocephalus is one of the most frequent and complex neurological diseases characterized by the abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain, due to an altered CSF dynamics. To detect possible ultrastructural alterations of the lateral ventricles choroid plexus (responsible for the CSF production), rats seven days after birth were submitted to an intracisternal injection of 20% kaolim (hydrated aluminum silicate) for the hydrocephalus induction. Twenty-eight or 35 days after injection, injected animals and respective controls were processed for observation under a transmission electron microscopy. Alterations found: presence of concentric cell membrane fragments, larger number of primary and secondary lysossomes, vacuoles, and cytoplasmic vesicles, and an enlargement of the intercellular space and between the basolateral interdigitation of the choroid epithelium. The alterations observed are probably associated to an increase of the ventricular pressure, inducing morpho-functional effects on the choroid plexus integrity.