vasoactive-intestinal-peptide and Learning-Disabilities

To evaluate whether peptides given to adult mice with Down syndrome prevent learning deficits, and to delineate the mechanisms behind the protective effect.. 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 γ-aminobutyric acid type A (GABAA)-α5. Statistics included analysis of variance and the Fisher protected least significant difference, with P<.05 significant.. 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).. 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.

Topics: Animals; Disease Models, Animal; Down Syndrome; Female; Glial Fibrillary Acidic Protein; Homeodomain Proteins; Learning Disabilities; Male; Mice; Mice, Inbred C57BL; Nerve Tissue Proteins; Oligopeptides; Peptide Fragments; Vasoactive Intestinal Peptide

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 gamma-aminobutyric acid type A (GABAA) receptors, and whether it is related to glial cells.. 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, GABAAbeta3, GABAAalpha5, 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 Fisher's protected least significant difference.. 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.. 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.

Topics: Animals; Cerebellum; Cerebral Cortex; Female; Fetal Alcohol Spectrum Disorders; Glial Fibrillary Acidic Protein; Hippocampus; Learning Disabilities; Male; Maze Learning; Mice; Mice, Inbred C57BL; Nerve Tissue Proteins; Neuroprotective Agents; Oligopeptides; Peptide Fragments; Pregnancy; Receptors, GABA-A; Receptors, N-Methyl-D-Aspartate; Vasoactive Intestinal Peptide

Blockage of vasoactive intestinal peptide (VIP) receptors during early embryogenesis in the mouse has been shown to result in developmental delays in neonates, and social behavior deficits selectively in adult male offspring. Offspring of VIP deficient mothers (VIP +/-) also exhibited developmental delays, and reductions in maternal affiliation and play behavior. In the current study, comparisons among the offspring of VIP deficient mothers (VIP +/-) mated to VIP +/- males with the offspring of wild type (WT) mothers mated to VIP +/- males allowed assessment of the contributions of both maternal and offspring VIP genotype to general health measures, social behavior, fear conditioning, and spatial learning and memory in the water maze. These comparisons revealed few differences in general health among offspring of WT and VIP deficient mothers, and all offspring exhibited normal responses in fear conditioning and in the acquisition phase of spatial discrimination in the water maze. WT mothers produced offspring that were normal in all tests; the reduced VIP in their VIP +/- offspring apparently did not contribute to any defects in the measures under study. However, regardless of their own VIP genotype, all male offspring of VIP deficient mothers exhibited severe deficits in social approach behavior and reversal learning. The deficits in these behaviors in the female offspring of VIP deficient mothers were less severe than in their male littermates, and the extent of their impairment was related to their own VIP genotype. This study has shown that intrauterine conditions had a greater influence on behavioral outcome than did genetic inheritance. In addition, the greater prevalence of deficits in social behavior and the resistance to change seen in reversal learning in the male offspring of VIP deficient mothers indicate a potential usefulness of the VIP knockout mouse in furthering the understanding of neurodevelopmental disorders such as autism.

Topics: Analysis of Variance; Animals; Behavior, Animal; Conditioning, Psychological; Exploratory Behavior; Fear; Female; Habituation, Psychophysiologic; Learning Disabilities; Male; Maze Learning; Mice; Mice, Knockout; Olfactory Pathways; Reflex; Reversal Learning; Sex Characteristics; Social Behavior; Spatial Behavior; Time Factors; Vasoactive Intestinal Peptide