Chronic intermittent ethanol exposure (CIE) is associated with degeneration of hippocampal neurons. The present study used hippocampal cultures to examine the loss of NeuN immunoreactivity, a relaible marker or neuronal density, after 1, 2, or 3 cycles of 5 days EtOH exposure (50 mM), followed by a 24-hour period of EWD or continuous EtOH exposure. NeuN immunoreactivity was decreased by 13%, 19%, and 16% in the CA1, CA3, and dentate gyrus after 3 cycles of CIE respectively; thionine staining confirmed significant cellular losses within each hippocampal subregion. Two cycles of CIE in aged tissue cultures resulted in significant decreases in NeuN immunoreactivity in all hippocampal subregions; however continuous ethanol exposure or exposure to one cycle of CIE did not. Further, exposure to the N-Methyl-D-aspartate receptor (NMDAR) antagonist 2-amino-7-phosphonvaleric acid (APV) (30 uM) during periods of EWD attenuated the loss of NeuN in all hippocampal subregions, while exposure to APV (40 uM) prevented the loss of NeuN in the CA1 and dentate gyrus. These results suggest that the loss of mature neurons after CIE is associated with the overactivation on the NMDAR.

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Placenta-specific 1 (Plac1) is an X-linked gene that is essential for normal placental development. Previous studies have shown that Plac1 is also expressed in the fetal brain and paternally imprinted. Its expression in the fetal brain is markedly downregulated immediately after birth. Plac1 ablation predisposes Plac1-null males and Xm-X Hets (inactive maternal allele) to an increased risk of developing lethal postnatal hydrocephalus suggesting a functional role for Plac1 during embryonic development. The objective of this study was to characterize the effect of Plac1 on brain development and postnatal function. In order to address this, a mutant Plac1 mouse model, established on the C57BL/6J background, was studied. Formalin-fixed, paraffin-embedded whole mount embryos and brain sections were obtained at various stages of development. Plac1 expression was assessed by qRT-PCR and immunohistochemistry (IHC). Brain structure was assessed by histopathological and magnetic resonance imaging (MRI) analysis. Behavioral analysis was conducted using the PhenoMaster automated cage system and a battery of classical behavioral tests. Our results revealed Plac1 expression throughout the embryonic brain when assessed by qRT-PCR and IHC at E16.5 and E18.5. MRI analysis of an adult Plac1 knockout (KO) brain revealed microcephaly (14%), reduced ventricular volume, and increased heterogeneity of the medulla compared to a WT brain. Consistent with these findings, H&E staining of the KO brain revealed a smaller cortical mantle, a dysmorphic hippocampus, and a dysmorphic cerebellum with reduced folia. IHC analyses of NF-M, NeuN, and Iba1 immunostaining revealed significant reductions in axonal and neuronal development and increased activated microglia in KO brain, but not in Xm-X Hets. Although no structural abnormalities were detected in Xm-X Hets, behavioral analyses did reveal reduced activity and behaviors consistent with increased anxiety. In conclusion, Plac1 is a paternally imprinted, X-linked gene that is associated with abnormal brain development, reduced activity, and specific behavioral abnormalities.

Neuronal Nuclei (NeuN) and Doublecortin (DCX) are neuron specific proteins that are used in histological studies of brain structure in a variety of vertebrate taxa.Antibodies against NeuN (anti-NeuN) bind to the Fox-3 protein, an RNA binding protein common in mature neurons. Anti-DCX labels a microtubule-associated protein expressed in actively dividing neural progenitor cells and migrating neurons. The DCX gene encodes a protein that is well conserved across mammalian, avian, and a few reptilian species, therefore anti-DCX staining has been used successfully across a range of vertebrate taxa. Successful neuronal staining using anti-NeuN has been demonstrated in mammals, birds, and the Testudines order (turtles). However, herpetologists who study neurobiology in squamates have had limited success with anti-NeuN and anti-DCX binding to their respective antigens. All commercially available anti-NeuN and anti-DCX antiserums were designed to mammalian antigens, and significant differences in tertiary structure divergence at the epitope where these antibodies bind may explain the failure of anti-NeuN and anti-DCX immunohistochemistry in many squamate species. This study aims to characterize evolutionary differences in gene and protein structure between two species of reptiles (Crotalus oreganus and Sceloporus occidentalis) and mammals. We sequenced the Fox-3 and DCX coding sequences using polymerase chain reaction (PCR) and Sanger sequencing, which allowed us to build phylogenetic trees comparing Fox-3 and DCX deduced protein structures. By identifying structural differences linked to evolutionary variation, new polyclonal antibodies specifically targeting Fox-3 and DCX in reptile brains can be developed to facilitate future investigations of neurogenesis and brain structure in squamate reptiles.

No description available.

Previous research on the relationship between spatial memory and adult hippocampal neurogenesis has been controversial. In the present study, neurogenesis was compared between two natural populations of the same species that differ in their reliance on spatial memory to cache and retrieve stored food. Western red squirrels store food in a single site whereas eastern red squirrels store food in multiple sites. Neurogenesis was assessed using endogenous markers of the number of proliferating cells (Ki-67) and the number of immature neurons (DCX), and neuronal recruitment was determined by measuring the area of the dentate gyrus of the hippocampus. The number of proliferating cells, immature neurons and neuronal recruitment were enhanced in the eastern compared to the western red squirrels, reflecting the food storing strategies used by the squirrels. This suggests that there is a positive correlation between adult hippocampal neurogenesis and spatial learning and memory.

Previous research on the relationship between spatial memory and adult hippocampal neurogenesis has been controversial. In the present study, neurogenesis was compared between two natural populations of the same species that differ in their reliance on spatial memory to cache and retrieve stored food. Western red squirrels store food in a single site whereas eastern red squirrels store food in multiple sites. Neurogenesis was assessed using endogenous markers of the number of proliferating cells (Ki-67) and the number of immature neurons (DCX), and neuronal recruitment was determined by measuring the area of the dentate gyrus of the hippocampus. The number of proliferating cells, immature neurons and neuronal recruitment were enhanced in the eastern compared to the western red squirrels, reflecting the food storing strategies used by the squirrels. This suggests that there is a positive correlation between adult hippocampal neurogenesis and spatial learning and memory.