Vanadium administration ameliorates cortical structural and functional changes in juvenile hydrocephalic mice

Vanadium is a prevalent neurotoxic transition metal with therapeutic potentials in some neurological conditions. Hydrocephalus poses a major clinical burden in neurological practice in Africa. Its primary treatment (shunting) has complications, including infection and blockage; alternative drug-based therapies are therefore necessary. This study investigates the function and cytoarchitecture of motor and cerebellar cortices in juvenile hydrocephalic mice following treatment with varying doses of vanadium. Fifty juvenile mice were allocated into five groups (n = 10 each): controls, hydrocephalus-only, low- (0.15 mg/kg), moderate- (0.3 mg/kg), and high- (3.0 mg/kg) dose vanadium groups. Hydrocephalus was induced by the intracisternal injection of kaolin and sodium metavanadate administered by intraperitoneal injection 72hourly for 28 days. Neurobehavioral tests: open field, hanging wire, and pole tests, were carried out to assess locomotion, muscular strength, and motor coordination, respectively. The cerebral motor and the cerebellar cortices were processed for cresyl violet staining and immunohistochemistry for neurons (NeuN) and astrocytes (glial fibrillary acidic protein). Hydrocephalic mice exhibited body weight loss and behavioral deficits. Horizontal and vertical movements and latency to fall from hanging wire were significantly reduced, while latency to turn and descend the pole were prolonged in hydrocephalic mice, suggesting impaired motor ability; this was improved in vanadium-treated mice. Increased neuronal count, pyknotic cells, neurodegeneration and reactive astrogliosis were observed in the hydrocephalic mice. These were mostly mitigated in the vanadium-treated mice, except in the high-dose group where astrogliosis persisted. These results demonstrate a neuroprotective potential of vanadium administration in hydrocephalus. The molecular basis of these effects needs further exploration.

Vanadium improves memory and spatial learning and protects the pyramidal cells of the hippocampus in juvenile hydrocephalic mice

Background

Hydrocephalus is a neurological condition known to cause learning and memory disabilities due to its damaging effect on the hippocampal neurons, especially pyramidal neurons. Vanadium at low doses has been observed to improve learning and memory abilities in neurological disorders but it is uncertain whether such protection will be provided in hydrocephalus. We investigated the morphology of hippocampal pyramidal neurons and neurobehavior in vanadium-treated and control juvenile hydrocephalic mice.

Methods

Hydrocephalus was induced by intra-cisternal injection of sterile-kaolin into juvenile mice which were then allocated into 4 groups of 10 pups each, with one group serving as an untreated hydrocephalic control while others were treated with 0.15, 0.3 and 3 mg/kg i.p of vanadium compound respectively, starting 7 days post-induction for 28 days. Non-hydrocephalic sham controls (n = 10) were sham operated without any treatment. Mice were weighed before dosing and sacrifice. Y-maze, Morris Water Maze and Novel Object Recognition tests were carried out before the sacrifice, the brains harvested, and processed for Cresyl Violet and immunohistochemistry for neurons (NeuN) and astrocytes (GFAP). The pyramidal neurons of the CA1 and CA3 regions of the hippocampus were assessed qualitatively and quantitatively. Data were analyzed using GraphPad prism 8.

Results

Escape latencies of vanadium-treated groups were significantly shorter (45.30 ± 26.30 s, 46.50 ± 26.35 s, 42.99 ± 18.44 s) than untreated group (62.06 ± 24.02 s) suggesting improvements in learning abilities. Time spent in the correct quadrant was significantly shorter in the untreated group (21.19 ± 4.15 s) compared to control (34.15 ± 9.44 s) and 3 mg/kg vanadium-treated group (34.35 ± 9.74 s). Recognition index and mean % alternation were lowest in untreated group (p = 0.0431, p=0.0158) suggesting memory impairments, with insignificant improvements in vanadium-treated groups. NeuN immuno-stained CA1 revealed loss of apical dendrites of the pyramidal cells in untreated hydrocephalus group relative to control and a gradual reversal attempt in the vanadium-treated groups. Astrocytic activation (GFAP stain) in the untreated hydrocephalus group were attenuated in the vanadium-treated groups under the GFAP stain. Pyknotic index in CA1 pyramidal layer of untreated (18.82 ± 2.59) and 0.15mg/kg vanadium-treated groups (18.14 ± 5.92) were significantly higher than control (11.11 ± 0.93; p = 0.0205, p = 0.0373) while there was no significant difference in CA3 pyknotic index across all groups.

Conclusion

Our results suggest that vanadium has a dose-dependent protective effect on the pyramidal cells of the hippocampus and on memory and spatial learning functions in juvenile hydrocephalic mice.

Deficits of Learning and Spatial Memory are Associated with Increased Pyknosis of Pyramidal Neurons of the Hippocampus of Adult Rats with Chronic Hydrocephalus

BACKGROUND

The hippocampus is the brain's centre for the consolidation of short-term and spatial memory that enables navigation. Hippocampal injury occurs in hydrocephalus and is associated with loss of memory.

OBJECTIVE

We assessed pyknotic changes in kaolin-induced chronic hydrocephalus in adult rats using qualitative and quantitative means, and related these to memory deficits in the rats.

METHODS

Adult rats were randomly divided into control and experimental groups. Hydrocephalus was induced by intracisternal injection of 0.1ml sterile kaolin suspension for 6weeks. Control rats received sham injections. Spatial memory was assessed with the Morris water maze test. Coronal sections of the brains were grouped into either mild or moderate hydrocephalus and then stained with H&E and cresyl violet stains. Thus, there were three groups: control, mild hydrocephalus and moderate hydrocephalus (n=10), respectively.

RESULTS

Shrinking and thinning of the hippocampal tissue, distortion of the pyramidal layer and pyknotic cells were observed in the CA1 and CA3 regions of the hydrocephalic rats. The pyknotic indices in the mild hydrocephalic rat (Cornus Ammonis, CA) CA1, CA2, CA3 (54.30±1.38; 27.62±0.83; 57.61±0.74) and moderate hydrocephalic rat CA1, CA2, CA3 (48.18±0.67; 32.00±0.84; 42.41±1.19) regions were significantly increased compared to the controls' CA1, CA2, CA3 (12.14±0.56; 9.21±0.36; 13.04±0.59).

CONCLUSION

Chronic hydrocephalus in adult rats was associated with cell death in all the regions of the hippocampus, irrespective of the degree of ventricular enlargement. The extent of cell death corresponded with the severity of learning and memory deficits.

CONTEXTE

L’hippocampe est le centre du cerveau pour la consolidation de la mémoire à court terme et de la mémoire spatiale qui permet la navigation. Une lésion de l’hippocampe se produit dans l’hydrocéphalie et est associée à la perte de mémoire.

OBJECTIF

Nous avons évalué les changements pyknotiques dans l’hydrocéphalie chronique induite par le kaolin chez des rats adultes en utilisant des moyens qualitatifs et quantitatifs, et nous les avons reliés aux déficits de mémoire chez les rats.

MÉTHODES

Des rats adultes ont été répartis au hasard en groupes témoins et expérimentaux. L’hydrocéphalie a été induite par injection intracisternale de 0,1 ml de suspension stérile de kaolin pendant 6 semaines. Les rats témoins ont reçu des injections simulées. La mémoire spatiale a été évaluée par le test du labyrinthe aquatique de Morris. Les sections coronales des cerveaux ont été regroupées en hydrocéphalie légère ou modérée, puis colorées au H&E et au crésyl violet. Il y avait donc trois groupes : contrôle, hydrocéphalie légère et hydrocéphalie modérée (n=10), respectivement.

RÉSULTATS

Un rétrécissement et un amincissement du tissu hippocampique, une distorsion de la couche pyramidale et des cellules pyknotiques ont été observés dans les régions CA1 et CA3 des rats hydrocéphales. Les indices pyknotiques dans les régions CA1, CA2 et CA3 des rats hydrocéphales légers (Cornus Ammonis, CA) (54,30±1,38 ; 27,62±0,83 ; 57,61±0,74) et des rats hydrocéphales modérés CA1, CA2 et CA3 (48. 18±0.67 ; 32.00±0.84 ; 42.41±1.19) ont été significativement augmentées par rapport aux régions CA1, CA2, CA3 des témoins (12.14±0.56 ; 9.21±0.36 ; 13.04±0.59).

CONCLUSION

L’hydrocéphalie chronique chez les rats adultes était associée à la mort cellulaire dans toutes les régions de l’hippocampe, quel que soit le degré d’élargissement ventriculaire. L’étendue de la mort cellulaire correspondait à la sévérité des déficits d’apprentissage et de mémoire.

MOTS CLÉS

Hydrocéphalie chronique, hippocampe, rats adultes, mémoire, cellules pyknotiques.

Changes in Neuronal Density of the Sensorimotor Cortex and Neurodevelopmental Behaviour in Neonatal Mice with Kaolin-Induced Hydrocephalus

INTRODUCTION

Hydrocephalus is a disorder in which the circulation of cerebrospinal fluid is altered in a manner that leads to its accumulation in the ventricles and subarachnoid space. Its impact on the neuronal density and networks in the overlying cerebral cortex in a time-dependent neonatal hydrocephalic process is largely unknown. We hypothesize that hydrocephalus will affect the cytoarchitecture of the cerebral cortical mantle of neonatal hydrocephalic mice, which will in turn modify sensorimotor processing and neurobehaviour.

OBJECTIVE

The purpose of this study is to probe the effect of hydrocephalus on 3 developmental milestones (surface righting reflex, cliff avoidance reflex, and negative geotaxis) and on cortical neuronal densities in neonatal hydrocephalic mice.

METHODS

Hydrocephalus was induced in 1-day-old mice by intracisternal injection of sterile kaolin suspension. The pups were tested for reflex development and sensorimotor ability using surface righting reflex (PND 5, 7, and 9), cliff avoidance (PND 6), and negative geotaxis (PND 10 and 12) prior to their sacrifice on PND 7, 14, and 21. Neuronal density and cortical thickness in the sensorimotor cortex were evaluated using atlas-based segmentation of the neocortex and boundary definition in 4-μm paraffin-embedded histological sections with hematoxylin and eosin as well as cresyl violet stains.

RESULTS

Surface righting and cliff avoidance activities were significantly impaired in hydrocephalic pups but no statistically significant difference was observed in negative geotaxis in both experimental and control pups. The neuronal density of the sensorimotor cortex was significantly higher in hydrocephalic mice than in age-matched controls on PND 14 and 21 (373.20 ± 21.54 × 10-6 μm2 vs. 157.70 ± 21.88 × 10-6 μm2; 230.0 ± 44.1 × 10-6 μm2 vs. 129.60 ± 3.72 × 10-6 μm2, respectively; p < 0.05). This was accompanied by reduction in the cortical thickness (µm) in the hydrocephalic mice on PND 7 (2,409 ± 43.37 vs. 3,752 ± 65.74, p < 0.05), PND 14 (2,035 ± 322.10 vs. 4,273 ± 67.26, p < 0.05), and PND 21 (1,676 ± 33.90 vs. 4,945 ± 81.79, p < 0.05) compared to controls.

CONCLUSION

In this murine model of neonatal hydrocephalus, the quantitative changes in the cortical neuronal population may play a role in the observed changes in neurobehavioural findings.

Morphological and neurohistological changes in adolescent rats administered with nicotine during intrauterine life

Tobacco smoking has been linked to many preventable diseases affecting various organs and systems of the body, including the brain. The current study was conducted to demonstrate the histological changes observable in the cerebral cortex of young Wistar rats exposed to nicotine during gestation. Vaginal smearing was conducted for the female Wistar rats to determine their oestrous cycle, after which they were exposed to male rats overnight, for mating. Pregnancy was confirmed and the pregnant rats were divided into 3 groups based on the 3 trimesters (A, B, C), with each group having a control and a treated subgroup. The Control Groups (A1, B1, C1) were given 0.1 ml of normal saline i. p., while the Treated Groups (A2, B2, C2) received 0.06 mg/kg/0.1 ml of nicotine intra-peritoneally. Treatment was for a period of 6 days only within each trimester for all subgroups. The pregnant animals were allowed to litter, and at postnatal day 35 they were sacrificed. The skull was dissected to expose and remove the brain; the temporal and parietal cortices were excised and fixed in 4% paraformaldehyde for histological tissue preparation, using cresyl fast violet staining techniques. Exposure of the developing brain to nicotine during gestation resulted in various degrees of abnormalities in the cytoarchitecture of the parietal and temporal cortices of young rats. The gestational period of nicotine exposure and specific cortical affectation are important factors to consider while investigating neurological abnormalities in offspring of tobacco smokers.