Robin Roberson

Prevention of Developmental Delays in a Down Syndrome Mouse Model

OBJECTIVE: To estimate whether prenatal treatment with neuroprotective peptides prevents the developmental delay and the glial deficit in the Ts65Dn mouse model for Down syndrome and to explore the peptides’ effects on achievement of normal development. METHODS: Pregnant Ts65Dn females were randomly assigned to NAPVSIPQ+SALLRSIPA or control and were treated by investigators blinded to treatment and genotype on gestational days 8–12. Offspring were tested from postnatal day 5 to 21 for motor and sensory milestones with standardized tests by operators blinded to the pup’s treatment and genotype. The pup’s genotype was determined after completion of all tests. Activity-dependent neurotrophic factor, glial fibrillary acidic protein, and vasoactive intestinal peptide expression were determined using real-time polymerase chain reaction. RESULTS: Trisomic mice achieved milestones with a significant delay in four of five motor and sensory milestones. Trisomic mice that were prenatally exposed to NAPVSIPQ+SALLRSIPA achieved developmental milestones at the same time as the controls in three of four motor and one of four sensory milestones (P<.01). Euploid pups prenatally treated with NAPVSIPQ+SALLRSIPA achieved developmental milestones significantly earlier than the euploid pups prenatally treated with placebo. Activity-dependent neurotrophic factor expression was significantly downregulated in the Ts65Dn brains compared with the controls, prenatal treatment with NAPVSIPQ+ SALLRSIPA prevented the activity-dependent neurotrophic factor decrease in the Ts65Dn brains, and the expression was not different from the controls. The glial marker glial fibrillary acidic protein demonstrated the known glial deficit in the Ts65Dn mice, and treatment with NAPVSIPQ+ SALLRSIPA prevented its downregulation. Lastly, vasoactive intestinal peptide levels were increased in the trisomic brains, whereas treatment with NAPVSIPQ+SALLRSIPA did not prevent its upregulation. CONCLUSION: Prenatal treatment with NAPVSIPQ and SALLRSIPA prevented developmental delay and the glial deficit in Down syndrome. These findings highlight a possibility for the prevention of developmental sequelae in Down syndrome and suggest a potential intervention during pregnancy that may improve the outcome.

Prevention of learning deficit in a Down syndrome model.

OBJECTIVE: To evaluate whether peptides given to adult mice with Down syndrome prevent learning deficits, and to delineate the mechanisms behind the protective effect. METHODS: Ts65Dn mice were treated for 9 days with peptides D-NAPVSIPQ (NAP)+D-SALLRSIPA (SAL) or placebo, and wild-type animals were treated with placebo. Beginning on treatment day 4, the mice were tested for learning using the Morris watermaze. Probe tests for long-term memory were performed on treatment day 9 and 10 days after treatment stopped. Open-field testing was performed before and after the treatment. Calibrator-normalized relative real-time polymerase chain reaction (PCR) with glyceraldehyde-3-phosphate dehydrogenase (GAPD) standardization was performed on the whole brain and hippocampus for activity-dependent neuroprotective protein, vasoactive intestinal peptide (VIP), glial fibrillary acidic protein (GFAP), NR2B, NR2A, and &ggr;-aminobutyric acid type A (GABAA)-&agr;5. Statistics included analysis of variance and the Fisher protected least significant difference, with P<.05 significant. RESULTS: The Ts65Dn plus placebo animals did not learn over the 5-day period compared with the controls (P<.001). The Ts65Dn +(D-NAP+D-SAL) learned significantly better than the Ts65Dn plus placebo (P<.05), and they retained learning similar to controls on treatment day 9, but not after 10 days of no treatment. Treatment with D-NAP+D-SAL prevented the Ts65Dn hyperactivity. Adult administration of D-NAP+D-SAL prevented changes in activity-dependent neuroprotective protein, intestinal peptide, and NR2B with levels similar to controls (all P<.05). CONCLUSION: Adult treatment with D-NAP+D-SAL prevented learning deficit in Ts65Dn, a model of Down syndrome. Possible mechanisms of action include reversal of vasoactive intestinal peptide and activity-dependent neuroprotective protein dysregulation, as well as increasing expression of NR2B, thus facilitating learning.

Reversal of alcohol-induced learning deficits in the young adult in a model of fetal alcohol syndrome.

OBJECTIVE: To evaluate whether treatment with neuroprotective peptides to young adult mice prenatally exposed to alcohol reverses alcohol-induced learning deficits in a mouse model of fetal alcohol syndrome, whether the mechanism involves the N-methyl-d-aspartate (NMDA) and γ-aminobutyric acid type A (GABAA) receptors, and whether it is related to glial cells. METHODS: C57Bl6/J mice were treated with alcohol (0.03 ml/g) or placebo on gestational day 8. On day 40, male mice exposed to alcohol in utero were treated daily for 10 days with D-NAPVSIPQ and D-SALLRSIPA (n=20) or placebo (n=13); and control offspring were treated with placebo (n=46), with the treatment blinded. Learning evaluation began after 3 days using the Morris watermaze and the T-maze. The hippocampus, cortex, and cerebellum were isolated. Expression of NR2A, NR2B, GABAAβ3, GABAAα5, vasoactive intestinal peptide (VIP), activity-dependent neuroprotective protein, and glial fibrillary acidic protein was measured using calibrator-normalized relative real-time polymerase chain reaction. Statistical analysis included analysis of variance and Fishers protected least significant difference. RESULTS: Treatment with D-NAPVSIPQ and D-SALLRSIPA reversed the alcohol-induced learning deficit in both learning tests as well as the NR2A and NR2B down-regulation in the hippocampus and the up-regulation of NR2A in the cortex and NR2B in the cortex and cerebellum (all P<.05). No significant differences were found in GABAA expression. Moreover, the peptides changed activity-dependent neuroprotective protein expression in the cortex (P=.016) but not the down-regulation of VIP (P=.883), probably because the peptides are downstream from VIP. CONCLUSION: Alcohol-induced learning deficit was reversed and expression of NR2A and NR2B was restored in the hippocampus and cortex of young adult mice treated with D-NAPVSIPQ and D-SALLRSIPA. Given the role of NMDA receptors in learning, this may explain in part the mechanism of prevention of alcohol-induced learning deficits by D-NAPVSIPQ and D-SALLRSIPA.

Prenatal NAP+SAL prevents developmental delay in a mouse model of Down syndrome through effects on N-methyl-D-aspartic acid and γ-aminobutyric acid receptors

OBJECTIVE Down syndrome (DS) affects 1/800 infants. Prenatal NAPVSIPQ (NAP) and SALLRSIPA (SAL) (NAP+SAL) prevent developmental delay in Ts65Dn mice, a mouse model of DS. We investigated whether this finding involves N-methyl-D-aspartic acid and gamma-aminobutyric acid (GABA) receptor subunits. STUDY DESIGN Pregnant Ts65Dn mice were treated with placebo or NAP+SAL on gestational days 8-12. After developmental delay prevention was shown, 4 trisomic (Ts), 4 control, and 3 Ts+NAP+SAL adult offspring brains (from 3 litters) were collected. Calibrator-normalized real-time polymerase chain reaction was performed using primers for N-methyl-D-aspartic acid subunits NR2A and NR2B, and for GABA subunits GABA(A)alpha5 and GABA(A)beta3 with glyceraldehyde-3-phosphate dehydrogenase standardization. Statistics included analysis of variance and Fisher PLSD with P < .05 as significant. RESULTS NR2A, NR2B, and GABA(A)beta3 levels were decreased in Ts vs control (all P < .05). Prenatal NAP+SAL increased NR2A, NR2B, and GABA(A)beta3 to levels similar to control (all P < .05). A significant difference in GABA(A)alpha5 levels was not found. CONCLUSION Prenatal NAP+SAL increases NR2A, NR2B, and GABA(A)beta3 expression in adult DS mice to levels similar to controls. This may explain how NAP+SAL improve developmental milestone achievement.

Prenatal Treatment Prevents Learning Deficit in Down Syndrome Model

Down syndrome is the most common genetic cause of mental retardation. Active fragments of neurotrophic factors release by astrocyte under the stimulation of vasoactive intestinal peptide, NAPVSIPQ (NAP) and SALLRSIPA (SAL) respectively, have shown therapeutic potential for developmental delay and learning deficits. Previous work demonstrated that NAP+SAL prevent developmental delay and glial deficit in Ts65Dn that is a well-characterized mouse model for Down syndrome. The objective of this study is to evaluate if prenatal treatment with these peptides prevents the learning deficit in the Ts65Dn mice. Pregnant Ts65Dn female and control pregnant females were randomly treated (intraperitoneal injection) on pregnancy days 8 through 12 with saline (placebo) or peptides (NAP 20 µg +SAL 20 µg) daily. Learning was assessed in the offspring (8–10 months) using the Morris Watermaze, which measures the latency to find the hidden platform (decrease in latency denotes learning). The investigators were blinded to the prenatal treatment and genotype. Pups were genotyped as trisomic (Down syndrome) or euploid (control) after completion of all tests. Statistical analysis: two-way ANOVA followed by Neuman-Keuls test for multiple comparisons, P<0.05 was used to denote statistical significance. Trisomic mice who prenatally received placebo (Down syndrome -placebo; n = 11) did not demonstrate learning over the five day period. DS mice that were prenatally exposed to peptides (Down syndrome-peptides; n = 10) learned significantly better than Down syndrome -placebo (p<0.01), and similar to control-placebo (n = 33) and control-peptide (n = 30). In conclusion prenatal treatment with the neuroprotective peptides (NAP+SAL) prevented learning deficits in a Down syndrome model. These findings highlight a possibility for the prevention of sequelae in Down syndrome and suggest a potential pregnancy intervention that may improve outcome.

Altered expression of KIF17, a kinesin motor protein associated with NR2B trafficking, may mediate learning deficits in a Down syndrome mouse model

OBJECTIVE Down syndrome (DS), a major cause of mental retardation, affects 1 of 800 newborns. Mouse models for Down syndrome have been studied and found to have developmental and learning deficits, including the Ts65Dn (DS) mouse model. N-methyl-D-aspartate receptor NR2B subunit enhances synaptic plasticity. The up-regulation of KIF17, a motor protein that transports NR2B to the synaptic region parallels up-regulation of synaptic NR2B. Down regulation of KIF17 reflects up-regulation of less plastic NR2A subunit. We evaluated NR2B, NR2A, and KIF17 in Ts65Dn and control mice. STUDY DESIGN Ts65Dn (4) and control (4) adult brains were collected; NR2A, NR2B, and KIF17 were measured by Western blot and quantified using National Institutes of Health Image software. Comparisons were made using analysis of variance, < .05 was considered significant. RESULTS There was a significant decrease in KIF17 (P = .04) level in Ts65Dn mice as compared with the control animals, but there were no significant differences in the levels of NR2A (P = .79) and NR2B (P = .96). CONCLUSION The significant decrease of KIF17 inTs65Dn animals may in part mediate cognitive defects in DS.

Neuroprotective peptides influence cytokine and chemokine alterations in a model of fetal alcohol syndrome

OBJECTIVE Fetal alcohol syndrome (FAS) is associated with intellectual disability and neurodevelopmental abnormalities. Neuroprotective peptides NAPVSIPQ (NAP) and SALLRSIPA (SAL) can prevent some of the alcohol-induced teratogenesis including fetal death, growth abnormalities, and learning impairment in part by preventing alcohol-induced alterations in N-methyl-D-aspartate receptor gene expression in a mouse model for FAS. We evaluated a panel of cytokines and chemokines to determine whether NAP plus SAL work through a cytokine/chemokine-mediated pathway in preventing these alterations. STUDY DESIGN Using a well-characterized FAS model, timed, pregnant C57BL6/J mice were treated on gestational day (E) 8 with alcohol (0.03 mL/g), placebo, or alcohol plus peptides. Embryos were evaluated at 2 time points: after 6 hours and 10 days later at E18. A panel of cytokines/chemokines was measured using a microsphere-based multiplex immunoassay (Luminex xMAP; Millipore, Billerica, MA). Statistical analysis included Kruskal-Wallis, with P < .05 considered significant. RESULTS Six hours after treatment, interleukin (IL)-6 and keratinocyte chemoattractant cytokine (KC) were not detectable in the control embryos. Alcohol treatment resulted in detectable levels and significant increases in IL-6 (median, 15.7; range, 10.1-45.9 pg/mL) and KC (median, 45.9; range, 32.5-99.1 pg/mL). Embryos exposed to alcohol plus NAP plus SAL had undetectable IL-6 and KC (both P < .003), similar to the controls. Alcohol exposure resulted in a significant increase of granulocyte colony-stimulating factor (G-CSF) (P < .003) as compared with controls, and treatment with NAP plus SAL prevented the alcohol-induced increase. IL-13 and IL-1β were decreased 6 hours after alcohol exposure, and exposure to alcohol plus NAP plus SAL did not completely ameliorate the decrease. At E18, 10 days after exposure, these alterations were no longer present. Several analytes (regulated upon activation, normal T cell expressed, and secreted, tumor necrosis factor-α, interferon-γ, and IL-4) were not detectable at either time point in any of the groups. CONCLUSION Prenatal alcohol exposure acutely results in a significant elevation of IL-6, G-CSF and the KC, which are known to affect N-methyl-D-aspartate receptors. NAP plus SAL treatment prevented alcohol-induced increases. This provides additional insight into the mechanism of alcohol damage in FAS and NAP plus SAL prevention of neurodevelopmental anomalies.

Alterations in phosphorylated cyclic adenosine monophosphate response element of binding protein activity: a pathway for fetal alcohol syndrome-related neurotoxicity.

OBJECTIVE Fetal alcohol syndrome (FAS) is the leading cause of a spectrum of preventable nongenetic learning and behavioral disorders. In adult (FAS) mice, we measured phosphorylated cyclic adenosine monophosphate response element of binding protein (pCREB) staining in hippocampal subregions to evaluate a possible mechanism underlying FAS learning deficits. STUDY DESIGN Pregnant C57BL6/J mice were treated on gestational day 8 with alcohol or control (saline). After learning assessment, the offspring were perfused for immunohistochemistry and brain sections probed using SER 133 pCREB antibody. Relative staining density was assessed using National Institutes of Health Image software. Statistical analysis included analysis of variance with P < .05 considered significant. RESULTS In all hippocampal subregions, pCREB staining was greater in the control animals than in the alcohol-treated group (P < or = .0001). CONCLUSION In utero alcohol exposure decreased pCREB activity in hippocampal subregions of adult mice. The dentate gyrus had the most robust cumulative decrease in pCREB staining, suggesting FAS adult learning deficits may correlate to enhanced dentate gyrus neurodegeneration.

Cytokine and Chemokine Alterations in Down Syndrome

OBJECTIVE Down syndrome (DS) is the leading genetic cause of intellectual disability, affecting ~1/800 newborns. Previously we have shown alterations in N-methyl-D-aspartic acid (NMDA) receptors and neuropeptides (activity-dependant neuroprotective protein, glia fibrillary acidic protein) in a murine model of DS. Cytokines and chemokines have neuromodulatory and neurotransmitter roles and interact with the NMDA receptors. The objective of this study was to evaluate if cytokines and chemokines in the hippocampus and cerebellum are altered in this model. STUDY DESIGN We used 8- to 10-month-old animals from the well-characterized mouse model of DS (Ts65Dn). Learning and memory were assessed in the Morris water maze with the Ts65Dn animals demonstrating a learning deficit. After completion of the behavioral testing, the brains were removed and the hippocampus and cerebellum were separated by microdissection. A panel of cytokines, chemokines, and fractalkine were measured in the protein lysates using a microsphere-based multiplex immunoassay (Luminex xMAP, Millipore) and normalized to total protein concentration. Statistical analysis included the nonparametric Mann-Whitney U for the cytokine, chemokine, and fractalkine levels; p < 0.05 was considered significant. RESULTS Levels (median [range]) of interleukin (IL)-1β (6.95 [0.11 to 43.5] versus 14.2 [0.2 to 36.8] pg/mL); granulocyte-macrophage colony-stimulating factor (GM-CSF; 3.97 [0.19 to 19.6] versus 19.2 [0.2 to 31.1] pg/mL), and macrophage inflammatory protein (MIP)-1α (20.3 [0.11 to 73.3] versus 37.0 [0.22 to 102.7] pg/mL) in the hippocampus from Ts65Dn were significantly lower compared with the euploid (control) animals. Many cytokines and chemokines were not detected in the hippocampus or cerebellum, and others were detectable but not different between the groups. CONCLUSION We found a decreased in GM-CSF, IL-1β, and MIP-1α in the hippocampus of DS pups. All three have known interactions with NMDA receptors and their decline may explain, in part, the learning deficits associated with DS.

Neuroprotective fractalkine in fetal alcohol syndrome

OBJECTIVE Neuroprotective peptides (NAP+SAL) can prevent some alcohol-induced damage in fetal alcohol syndrome(FAS). Fractalkine, a chemokine constitutively expressed in the CNS reduces neuronal death from activated microglia. Using a model of FAS we evaluated if fractalkine is altered and if NAP+SAL work through fractalkine. STUDY DESIGN Using a FAS model, C57BL6/J-mice were treated on gestational day 8 with alcohol (0.03 mL/g), placebo or alcohol+peptides. Embryos were harvested after 6h(E8) and 10 days later(E18). Fractalkine was measured in the protein lysate (Luminex xMAP). Statistical analysis included Kruskal-Wallis. RESULTS Fractalkine was significantly elevated at 6h (median 341 pg/ml, range 263-424 pg/ml) vs. controls (median 228 pg/ml, range 146-332 pg/ml; P<.001). NAP+SAL prevented the alcohol-induced increase (median 137, range 97-255 pg/ml, P<.001). At E18, fractalkine levels were similar in all groups (P=0.7). CONCLUSION Prenatal alcohol exposure acutely elevates fractalkine, perhaps in an effort to counter the alcohol toxicity. Pre-treatment with NAP+SAL prevents the acute increase in fractalkine.