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

Noradrenergic Pathways Involved in Micturition in an Animal Model of Hydrocephalus-Implications for Urinary Dysfunction

Hydrocephalus is characterized by enlargement of the cerebral ventricles, accompanied by distortion of the periventricular tissue. Patients with hydrocephalus usually experience urinary impairments. Although the underlying etiology is not fully described, the effects of hydrocephalus in the neuronal network responsible for the control of urination, which involves periventricular areas, including the periaqueductal gray (PAG) and the noradrenergic locus coeruleus (LC). In this study, we aimed to investigate the mechanisms behind urinary dysfunction in rats with kaolin-induced hydrocephalus. For that purpose, we used a validated model of hydrocephalus-the rat injected with kaolin in the cisterna magna-also presents urinary impairments in order to investigate the putative involvement of noradrenergic control from the brain to the spinal cord Onuf's nucleus, a key area in the motor control of micturition. We first evaluated bladder contraction capacity using cystometry. Since our previous characterization of the LC in hydrocephalic animals showed increased levels of noradrenaline, we then evaluated the noradrenergic innervation of the spinal cord's Onuf's nucleus by measuring levels of dopamine β-hydroxylase (DBH). We also evaluated the expression of the c-Fos protooncogene, the most widely used marker of neuronal activation, in the ventrolateral PAG (vlPAG), an area that plays a major role in the control of urination by its indirect control of the LC via pontine micturition center. Hydrocephalic rats showed an increased frequency of bladder contractions and lower minimum pressure. These animals also presented increased DBH levels at the Onuf´s nucleus, along with decreased c-Fos expression in the vlPAG. The present findings suggest that impairments in urinary function during hydrocephalus may be due to alterations in descending noradrenergic modulation. We propose that the effects of hydrocephalus in the decrease of vlPAG neuronal activation lead to a decrease in the control over the LC. The increased availability of noradrenaline production at the LC probably causes an exaggerated micturition reflex due to the increased innervation of the Onuf´s nucleus, accounting for the urinary impairments detected in hydrocephalic animals. The results of the study provide new insights into the neuronal underlying mechanisms of urinary dysfunction in hydrocephalus. Further research is needed to fully evaluate the translational perspectives of the current findings.

Celecoxib attenuates neuroinflammation, reactive astrogliosis and promotes neuroprotection in young rats with experimental hydrocephalus

Hydrocephalus is a neurological condition with altered cerebrospinal fluid flow (CSF). The treatment is surgical and the most commonly used procedure is ventricle-peritoneal shunt. However, not all patients can undergo immediate surgery or achieve complete lesion reversal. Neuroprotective measures are valuable in such cases. It was evaluated whether the use of celecoxib, a selective inhibitor of COX-2, associated or not with ventricular-subcutaneous derivation, could offer benefits to the brain structures affected by experimental hydrocephalus. Seven-day-old male Wistar Hannover rats induced by intracisternal injection of kaolin 15% were used, divided into five groups with ten animals each: intact control (C), untreated hydrocephalus (H), hydrocephalus treated with celecoxib 20 mg/kg intraperitoneal (HTC), hydrocephalus treated with shunt (HTS) and hydrocephalus treated with shunt and celecoxib 20 mg/kg intraperitoneal (HTCS). Celecoxib was administered for 21 consecutive days, starting the day after hydrocephalus induction and continuing until the end of the experimental period. The surgery was performed seven days after inducing hydrocephalus. Multiple assessment methods were used, such as behavioral tests (water maze and open field), histological analysis (hematoxylin and eosin), immunohistochemistry (caspase-3, COX-2, and GFAP), and ELISA analysis of GFAP. The results of the behavioral and memory tests indicated that celecoxib improves the neurobehavioral response. The improvement can be attributed to the reduced neuroinflammation (p < 0.05), and astrogliosis (p < 0.05) in different brain regions. In conclusion, the results suggest that celecoxib holds great potential as an adjuvant neuroprotective drug for the treatment of experimental hydrocephalus.

The Improved Brain-Targeted Drug Delivery of Edaravone Temperature-Sensitive Gels by Ultrasound for γ-ray Radiation-Induced Brain Injury

Radiation-induced brain injury (RBI) is a common neurological disease caused by ionizing radiation (IR). Edaravone (EDA) is a free radical scavenger, has the potential to treat RBI. EDA loaded temperature-sensitive gels (TSGs) were prepared for subcutaneous injection to improve inconvenient administration of intravenous infusion. RBI mice model was established by irradiation of 60Co γ-ray on head. EDA TSGs could improve spontaneous behavior, learning and memory and anxiety of RBI mice by behavior tests, including the open field test, the novel object recognition test, the elevated plus maze test and the fear conditioning test. The therapeutic effects were enhanced with the assistance of ultrasound. Alleviative pathological changes, decreased the expression of Molondialdehyde (MDA) and Interleukin-6 (IL-6) in the hippocampus of brain, indicated reduced oxidative stress and inflammatory response with the treatment of EDA TSGs and ultrasound. Moreover, ultrasound was superior to the use of EDA TSGs. Safe and effective EDA TSGs were prepared for RBI, and the feasibility of brain-targeted drug delivery enhanced by ultrasound was preliminarily demonstrated in this study.

Memantine associated with ventricular-subcutaneous shunt promotes behavioral improvement, reduces reactive astrogliosis and cell death in juvenile hydrocephalic rats

Hydrocephalus is defined as the accumulation of cerebrospinal fluid in the brain ventricles. The usual treatment of hydrocephalus is surgical (shunt), but not all patients can undergo treatment immediately after diagnosis. Thus, neuroprotective measures were tested to minimize the tissue damage involved. Memantine is a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, which has shown a neuroprotective action in neurodegenerative diseases. This study aimed to evaluate the neuroprotective response of memantine in animals treated with or without a ventricular-subcutaneous shunt. Seven-day-old male Wistar rats induced by intracisternal injection of kaolin were used, divided into five groups: intact control (n=10), hydrocephalic (n=10), hydrocephalic treated with memantine (20mg/kg/day) (n=10), hydrocephalic treated with shunt (n=10), hydrocephalic treated with shunt and memantine (20mg/kg/day) (n=10). Memantine administration was started on the day after hydrocephalus induction and continued until the last day of the experimental period, totaling 21 consecutive days of drug application. The CSF shunt surgery was performed seven days after hydrocephalus induction. Behavioral tests (open field, and modified Morris water maze), histological, and immunohistochemical evaluations were performed. Treatment with memantine resulted in significant improvement (p<0.05) in sensorimotor development, preservation of spatial memory, reduction of astrocytic reaction in the corpus callosum, cortex, and germinal matrix. When associated with the shunt, it has also been shown to reduce the cell death cascade. It is concluded that memantine is a promising adjuvant drug with beneficial potential for the treatment of lesions secondary to hydrocephalus.