Persistent neocortical astrogliosis in adult wistar rats following prenatal ethanol exposure

Astroglial correlates of neuropsychiatric disease: From astrocytopathy to astrogliosis

Complex roles for astrocytes in health and disease continue to emerge, highlighting this class of cells as integral to function and dysfunction of the nervous system. In particular, escalating evidence strongly implicates a range of changes in astrocyte structure and function associated with neuropsychiatric diseases including major depressive disorder, schizophrenia, and addiction. These changes can range from astrocytopathy, degeneration, and loss of function, to astrogliosis and hypertrophy, and can be either adaptive or maladaptive. Evidence from the literature indicates a myriad of changes observed in astrocytes from both human postmortem studies as well as preclinical animal models, including changes in expression of glial fibrillary protein, as well as changes in astrocyte morphology and astrocyte-mediated regulation of synaptic function. In this review, we seek to provide a comprehensive assessment of these findings and consequently evidence for common themes regarding adaptations in astrocytes associated with neuropsychiatric disease. While results are mixed across conditions and models, general findings indicate decreased astrocyte cellular features and gene expression in depression, chronic stress and anxiety, but increased inflammation in schizophrenia. Changes also vary widely in response to different drugs of abuse, with evidence reflective of features of astrocytopathy to astrogliosis, varying across drug classes, route of administration and length of withdrawal.

Retinal structure and function in monkeys with fetal alcohol exposure

Exposure to ethanol in utero leads to several brain development disorders including retinal abnormalities whose underlying cellular pathogenesis remains elusive. We recently reported that fetal alcohol exposure (FAE) in vervet monkeys induces anomalies of full-field electroretinogram (ERG) waveforms that suggest premature aging of the retina. The goal of this study is to characterize the anatomo-functional mechanisms underlying the retinal changes observed in fetal alcohol exposed (FAE) monkeys, and age- and sex-matched normals. First, we examined in vivo the fundus of the eyes, measured intraocular pressure (IOP) and assessed cone activity using flicker ERG. Second, we investigated ex vivo, protein expression and anatomical organization of the retina using Western blotting, classical histology and immunohistochemistry. Our results indicated that the fundus of the eyes showed both, increased vascularization (tessellated fundus) and IOP in FAE monkeys. Furthermore, light-adapted flicker responses above 15 Hz were also significantly higher in FAE monkeys. Although there were no obvious changes in the overall anatomy in the FAE retina, Glial Fibrillary Acidic Protein (GFAP, a potent marker of astrocytes) immunoreactivity was increased in the FAE retinal ganglion cell layer indicating a strong astrogliosis. These alterations were present in juvenile (2 years old) monkeys and persist in adults (8 years old). Moreover, using specific cell type markers, no significant modifications in the morphology of the photoreceptors, horizontal cells, bipolar cells, and amacrine cells were observed. Our data indicate that FAE does indeed induce anatomical changes within the retinal ganglion cell layer that are reflected in the increased photosensitivity of the cone photoreceptors.

Effect of low-alcohol drinks on CNS structures in young animals

Adaptation restructuring at the level of cells and cell populations in CNS in young animals after acute intoxication with a high dose of beer was evaluated by a complex of quantitative morphometric parameters. Variants of morphological manifestations of compensatory adaptive changes were studied and variability of their combinations in the neuroglial populations of the forebrain, cerebellum, and spinal cord in young animals was revealed reflecting plastic potentialities of the studied CNS structures exposed to a destructive factor.

Galectin-1 attenuates astrogliosis-associated injuries and improves recovery of rats following focal cerebral ischemia

Astrogliosis occurs after brain ischemia, and excessive astrogliosis can devastate the neuronal recovery. Previous reports show that galectin-1 (Gal-1) regulates proliferation of several cell types and plays an important role after nervous system injuries. Here, we found that expression of Gal-1 was remarkably up-regulated in activated astrocytes around ischemic infarct. Furthermore, under ischemic conditions either in vitro or in vivo, Gal-1 was found to inhibit the proliferation of astrocytes in a dose-dependent manner, attenuate astrogliosis and down-regulate the astrogliosis associated expression of nitric oxide synthase and interleukin-1β after the ischemia. All these changes were blocked by lactose, suggesting a lectin dependent manner of Gal-1's function. Moreover, 7-day Gal-1 treatment reduced apoptosis of neurons, decreased brain infarction volume and improved neurological function induced by the ischemia. Together, these findings indicate that through reducing astrogliosis related damages, Gal-1 is a potential therapeutical target for attenuating neuronal damage and promoting recovery of brain ischemia.

Binge-like postnatal alcohol exposure triggers cortical gliogenesis in adolescent rats

The long-term effects of binge-like postnatal alcohol exposure on cell proliferation and differentiation in the adolescent rat neocortex were examined. Unlike the hippocampal dentate gyrus, where proliferation of progenitors results primarily in addition of granule cells in adulthood, the vast majority of newly generated cells in the intact mature rodent neocortex appear to be glial cells. The current study examined cytogenesis in the motor cortex of adolescent and adult rats that were exposed to 5.25 g/kg/day of alcohol on postnatal days (PD) 4-9 in a binge manner. Cytogenesis was examined at PD50 (through bromodeoxyuridine [BrdU] labeling) and survival of these newly generated cells was evaluated at PD80. At PD50, significantly more BrdU-positive cells were present in the motor cortex of alcohol-exposed rats than controls. Confocal analysis revealed that the majority (>60%) of these labeled cells also expressed NG2 chondroitin sulfate proteoglycan (NG2 glia). Additionally, survival of these newly generated cortical cells was affected by neonatal alcohol exposure, based on the greater reduction in the number of BrdU-labeled cells from PD50 to PD80 in the alcohol-exposed animals compared to controls. These findings demonstrate that neonatal alcohol exposure triggers an increase in gliogenesis in the adult motor cortex.

Assessment of the astrogliotic responses of three human astrocytoma cell lines to ethanol, trimethyltin chloride and acrylamide

The astrogliotic responses of the CCF-STTG1, U251-MG, and U373-MG human astrocytoma lines were determined after exposure to ethanol, trimethyltin chloride (TMTC), and acrylamide over 4, 16, and 24h. Basal glial fibrillary acidic protein (GFAP) expression in the U-251MG and U373-MG cells was 10-fold greater than the CCF-STGG1 line. Ethanol treatment over 24h, but not at 4 and 16h, resulted in significant increases in GFAP in all three glioma lines at sub-cytotoxic levels; the GFAP responses in the CCF-STTG1 line were the most sensitive, as concentrations of 0.1 and 1mM led to increases in GFAP expression compared with control of 56.8+/-15.7 and 58.9+/-11.5%, respectively (P<0.05). Treatment with TMTC (1 microM) over 4h showed elevated GFAP expression in the U251-MG cell line to 28.0+/-15.7% above control levels (P<0.01), but not in the other U373-MG or CCF-STTG1 cells. At 4h, MTT turnover was markedly increased compared with control, particularly in the U373-MG line at concentrations as low as 1 microM (17.1+/-2.3%; P<0.01). TMTC exposure over 16 and 24h resulted in reduction in GFAP expression in all three lines at concentrations; at 24h incubation, the reduction was >50% (P<0.01). There were no changes in GFAP expression or MTT turnover in response to acrylamide except at the highest concentration ranges of 10-100 mM. This study underlines the significance of period of exposure, as well as toxin concentration in astrocytoma cellular response to toxic pressure.

Neocortical neurodegeneration in young adult Wistar rats prenatally exposed to ethanol

This study was aimed to determine the persistence of neurodegeneration in the cerebral cortex of adult Wistar rats following prenatal ethanol exposure. Timed pregnant rats maintained on standard mouse chow (Ladokun Feeds, Ibadan, Nigeria) and water ad libitum were used for the study. The rats were divided randomly into groups A and B (n-6) and C (n = 4). Group A received a daily ethanol dose of 5.8 g/Kg body weight/day, on the 9th, 10th, 11th, and 12th days of gestation by intragastric intubation, at 16.00 h (PEE) group B was pair-fed with the ethanol dams on isocaloric solution of sucrose for the same duration (PF), while group C received standard chow (C) and water ad libitum. At birth, the pups were weighed and weaned at 30 days of age. Wet brain weights of adult offsprings were determined at 42 days of age. Following whole body perfusion-fixation after anaesthesia, specimens of the neocortex were processed routinely for paraffin embedding and sections of 6 mum thickness stained for neurohistology from each group. Another set of specimens was cryosectioned at -23 degrees C and evaluated for apoptosis by the TUNEL method. The study showed a significantly sustained 44% reduction in brain weight. Neurodegeneration was evident in the layer V, consisting of mostly pyknotic pyramidal neurons, with broken dendrites, collapsed cell bodies, obliterated nuclei and nucleoli. There was a 55% decrease in the normal pyramidal neuron cell pack density. The negative TUNEL signals in both groups suggest that apoptosis may play no role in the mechanism of action occurring at this age of the animals. These sustained changes may underlie the neurobehavioural deficits that have been variously reported.