Luana de Nazaré da Silva Santana

Hippocampal neuronal loss, decreased GFAP immunoreactivity and cognitive impairment following experimental intoxication of rats with aluminum citrate

Aluminum (Al) is a neurotoxic agent with deleterious actions on cognitive processes. Nevertheless, few studies have investigated the neuropathological effects underlying the Al-induced cognitive impairment. We have explored the effects of acute Al citrate intoxication on both hippocampal morphology and mnemonic processes in rodents. Adult male Wistar rats were intoxicated with a daily dose of Al citrate (320 mg/kg) during 4 days by gavage. Animals were perfused at 8 (G2), 17 (G3) and 31 days (G4) after intoxication. Control animals were treated with sodium citrate (G1). Animals were submitted to behavioral tests of open field and elevated T-maze. Immunohistochemistry was performed to label neurons (anti-NeuN) and astrocytes (anti-GFAP) in both CA1 and CA3 hippocampal regions. There was an increase in the locomotor activity in open field test for G2 in comparison to control group and other groups (ANOVA-Bonferroni, P<0.05). The elevated T-maze avoidance latency (AL) was higher in all intoxicated groups compared to control (P<0.05) in avoidance 1. These values remained elevated in avoidance 2 (P<0.05), but abruptly decreased in G2 and G3, but not in G1 and G4 animals in avoidance 3 (P<0.05). There were no significant differences for 1 and 2 escape latencies. There were intense neuronal loss and a progressive decrease in GFAP immunoreactivity in the hippocampus of intoxicated animals. The results suggest that Al citrate treatment induces deficits on learning and memory concomitant with neuronal loss and astrocyte impairment in the hippocampus of intoxicated rats.

Evaluation of the Effects of Chronic Intoxication with Inorganic Mercury on Memory and Motor Control in Rats

The aims of this study were to evaluate whether chronic intoxication with mercury chloride (HgCl2), in a low concentration over a long time, can be deposited in the central nervous tissue and to determine if this exposure induces motor and cognitive impairments. Twenty animals were intoxicated for 45 days at a dose of 0.375 mg/kg/day. After this period, the animals underwent a battery of behavioral tests, in a sequence of open field, social recognition, elevated T maze and rotarod tests. They were then sacrificed, their brains collected and the motor cortex and hippocampus dissected for quantification of mercury deposited. This study demonstrates that long-term chronic HgCl2 intoxication in rats promotes functional damage. Exposure to HgCl2 induced anxiety-related responses, short- and long-term memory impairments and motor deficits. Additionally, HgCl2 accumulated in both the hippocampus and cortex of the brain with a higher affinity for the cortex.

Neurodegeneration and Glial Response after Acute Striatal Stroke: Histological Basis for Neuroprotective Studies

Stroke is a leading cause of death and neurological disability worldwide and striatal ischemic stroke is frequent in humans due to obstruction of middle cerebral artery. Several pathological events underlie damage progression and a comprehensive description of the pathological features following experimental stroke in both acute and chronic survival times is a necessary step for further functional studies. Here, we explored the patterns of microglial activation, astrocytosis, oligodendrocyte damage, myelin impairment, and Nogo-A immunoreactivity between 3 and 30 postlesion days (PLDs) after experimental striatal stroke in adult rats induced by microinjections of endothelin-1 (ET-1). The focal ischemia induced tissue loss concomitant with intense microglia activation between 3 and 14 PLDs (maximum at 7 PLDs), decreasing afterward. Astrocytosis was maximum around 7 PLDs. Oligodendrocyte damage and Nogo-A upregulation were higher at 3 PLDs. Myelin impairment was maximum between 7 and 14 PLDs. Nogo-A expression was higher in the first week in comparison to control. The results add important histopathological features of ET-1 induced stroke in subacute and chronic survival times. In addition, the establishment of the temporal evolution of these neuropathological events is an important step for future studies seeking suitable neuroprotective drugs targeting neuroinflammation and white matter damage.

Validation of reference genes for ovarian tissue from capuchin monkeys (Cebus apella).

There is no tradition in studies reporting the effect of exposure to cryoprotectants or simply hypoxia and hypothermia on gene expression in the ovarian tissue and there has been only one study on reference or target genes quantification, and comparisons of normoxic with hypoxic, hypothermic and toxic conditions. Our aim in the present study was to investigate the stability of three reference genes in the ovarian tissue of capuchin monkeys (Cebus apella). To this end, fresh and cryoprotectant-exposed ovarian biopsies were used. Both fresh and exposed ovarian tissues were subjected to total RNA extraction and synthesis of cDNA. cDNA was amplified by real-time polymerase chain reaction (PCR), and GeNorm, BestKeeper and NormFinder software were used to evaluate the stability of glyceraldehyde-2-phosphate dehydrogenase (GAPDH), hypoxanthine phosphoribosyltransferase 1 (HPRT1) and TATA-binding protein (TBP). Results demonstrated that, in the ovarian tissue from capuchin monkeys, HPRT1 and TBP were the most suitable reference genes and thus could be used as parameters to normalize data in future studies. In contrast, GAPDH appeared as the least stable gene among the tested reference genes. In conclusion, HPRT1 and TBP were the most stable reference genes in fresh and cryoprotectant-exposed ovarian tissue from capuchin monkeys.

Adaptation of a trap door technique for the recovery of ovarian cortical biopsies from Cebus apella (capuchin monkey).

There is a paucity of efficient cryopreservation protocols for primordial follicles enclosed in the ovarian tissue from non-human primates (NHP), in special New World primates. Our objective was to establish an optimal procedure for the recovery of ovarian biopsies from capuchin monkeys. To this end, we adapted a trap door biopsy method. Follicular density and quality of the biopsies were evaluated and ultrasound analysis was performed before and continuously after surgery to assess ovarian structure. Ovarian tissue biopsies recovered by the trap door technique allowed the successful harvesting of primordial follicles from capuchin monkeys, and no complication was recorded. The female cycle was not affected by surgery and no adherence was found thereafter. In conclusion, the adaptation of a trap door biopsy method is a safe procedure and allows recovery of healthy primordial follicles.

Vitrification of Ovarian Tissue from Primates and Domestic Ruminants: An Overview

In the last decade, vitrification protocols to preserve human ovarian tissue have been regularly reported, even more often than the protocols developed for large mammals, such as ruminants and nonhuman primates. In order to facilitate the use of domestic ruminants (cows, goats, and sheep) and nonhuman primates as animal models, application of similar protocols as used for human material is performed. Next to it, the addition of indispensable or exclusion of avoidable compounds in the vitrification of human ovarian tissue should be tested in such experiments with animal models. The objective of this mini-review is to summarize the current protocols used for the vitrification of ovarian tissue and to evaluate the vitrification methods in humans, nonhuman primates, and domestic ruminants.

Repeated Cycles of Binge-Like Ethanol Intake in Adolescent Female Rats Induce Motor Function Impairment and Oxidative Damage in Motor Cortex and Liver, but Not in Blood

Moderate ethanol consumption (MEC) is increasing among women. Alcohol exposure usually starts in adolescence and tends to continue until adulthood. We aimed to investigate MEC impacts during adolescence until young adulthood of female rats. Adolescent female Wistar rats received distilled water or ethanol (3 g/kg/day), in a 3 days on-4 days off paradigm (binge drinking) for 1 and 4 consecutive weeks. We evaluate liver and brain oxidative damage, peripheral oxidative parameters by SOD, catalase, thiol contents, and MDA, and behavioral motor function by open-field, pole, beam-walking, and rotarod tests. Our results revealed that repeated episodes of binge drinking during adolescence displayed lipid peroxidation in the liver and brain. Surprisingly, such oxidative damage was not detectable on blood. Besides, harmful histological effects were observed in the liver, associated to steatosis and loss of parenchymal architecture. In addition, ethanol intake elicited motor incoordination, bradykinesia, and reduced spontaneous exploratory behavior in female rats.