Inhibition of murine embryonic growth by human immunodeficiency virus envelope protein and its prevention by vasoactive intestinal peptide and activity-dependent neurotrophic factor.

Intrauterine growth retardation and neurodevelopmental handicaps are common among infants born to HIV-positive mothers and may be due to the actions of virions and/or maternally derived viral products. The viral envelope protein, gp120, is toxic to neurons, induces neuronal dystrophy, and retards behavioral development in neonatal rats. Vasoactive intestinal peptide, a neuropeptide regulator of early postimplantation embryonic growth, and the neuroprotective protein, activity-dependent neurotrophic factor, prevent gp120-induced neurotoxicity. Whole embryo culture of gestational day 9.5 mouse embryos was used to assess the effect of gp120 on growth. Embryos treated with gp120 exhibited a dose-dependent inhibition of growth. gp120-treated embryos (10(-8) M) grew 1.2 somites in the 6-h incubation period, compared with 3.9 somites by control embryos. Embryos treated with gp120 were significantly smaller in cross-sectional area and had significantly less DNA and protein than controls. Growth inhibition induced by gp120 was prevented by cotreatment with vasoactive intestinal peptide or activity-dependent neurotrophic factor. gp120 may play a role in the growth retardation and developmental delays experienced by infants born to HIV-positive mothers. Vasoactive intestinal peptide and related factors may provide a therapeutic strategy in preventing developmental deficits.

Maternal vasoactive intestinal peptide and the regulation of embryonic growth in the rodent.

Vasoactive intestinal peptide (VIP) has been shown to regulate early postimplantation growth in rodents through central nervous system receptors. However, the source of VIP mediating these effects is unknown. Although VIP binding sites are present prenatally, VIP mRNA was not detected in the rat central nervous system before birth and was detected in the periphery only during the last third of pregnancy. In the present study, the embryonic day (E11) rat embryo/trophoblast was shown to have four times the VIP concentration of the E17 fetus and to have VIP receptors in the central nervous system. However, no VIP mRNA was detected in the E11 rat embryo or embryonic membranes by in situ hybridization or reverse transcriptase-PCR. RIA of rat maternal serum revealed a peak in VIP concentration at days E10-E12 of pregnancy, with VIP rising to levels 6-10-fold higher than during the final third of pregnancy. After intravenous administration of radiolabeled VIP to pregnant female mice, undegraded VIP was found in the E10 embryo. These results suggest that maternal tissues may provide neuroendocrine support for embryonic growth through a surge of VIP during early postimplantation development in the rodent.

Caspase-mediated degradation of AMPA receptor subunits: a mechanism for preventing excitotoxic necrosis and ensuring apoptosis.

Activation of ionotropic glutamate receptors of the AMPA and NMDA subtypes likely contributes to neuronal injury and death in various neurodegenerative disorders. Excitotoxicity can manifest as either apoptosis or necrosis, but the mechanisms that determine the mode of cell death are not known. We now report that levels of AMPA receptor subunits GluR-1 and GluR-4 are rapidly decreased in cultured rat hippocampal neurons undergoing apoptosis in response to withdrawal of trophic support (WTS), whereas levels of NMDA receptor subunits NR1, NR2A, and NR2B are unchanged. Exposure of isolated synaptosomal membranes to "apoptotic" cytosolic extracts resulted in rapid degradation of AMPA receptor subunits. Treatment of cells and synaptosomal membranes with the caspase inhibitors prevented degradation of AMPA receptor subunits, demonstrating a requirement for caspases in the process. Calcium responses to AMPA receptor activation were reduced after withdrawal of trophic support and enhanced after treatment with caspase inhibitors. Vulnerability of neurons to excitotoxic necrosis was decreased after withdrawal of trophic support and potentiated by treatment with caspase inhibitors. Our data indicate that caspase-mediated degradation of AMPA receptor subunits occurs during early periods of cell stress and may serve to ensure apoptosis by preventing excitotoxic necrosis.

Role of insulin-like growth factors in peripheral nerve regeneration.

Prolonged denervation results in atrophy of target organs and increased risk of permanent paralysis. A better understanding of the mechanism responsible for nerve regeneration may one day lead to improved rates of nerve regeneration and diminished risk of loss of function. Neurobiologists have known for decades that soluble neurotrophic activity is present in nerves and nerve targets. Until recently, the soluble molecules that regulate the rate of nerve regeneration have eluded identification. Insulin-like growth factor (IGF) gene expression is correlated with synapse formation during development and regeneration. IGFs are now identified as the first soluble nerve- and muscle-derived neurotrophic factors found to regulate the rate of peripheral nerve regeneration. The roles of IGFs and other neurotrophic factors in peripheral nerve regeneration, motor nerve terminal sprouting and synapse formation are reviewed.

Localization of glial cell line-derived neurotrophic factor receptor alpha and c-ret mRNA in rat central nervous system.

Glial cell line-derived neurotrophic factor (GDNF) is a neurotrophic factor that influences the survival and function of several neuronal populations in the central (CNS) and peripheral nervous systems. The actions of GDNF are mediated by a multicomponent receptor complex composed of the tyrosine kinase product of c-ret and the ligand-binding protein GDNF receptor alpha (GDNFR-alpha). In the present study, we used in situ hybridization to localize cells expressing the mRNA for these GDNF receptor subunits in rat CNS. As reported previously, GDNFR-alpha and c-ret mRNA are present in the substantia nigra and ventral tegmental area, regions containing GDNF-responsive dopamine neurons. However, both mRNA were found in motor neurons of spinal cord and brainstem nuclei that innervate skeletal muscle. These areas include alpha motor neurons in the ventral horn of spinal cord and neurons in hypoglossal, facial, trigeminal, and abducens nuclei. In areas rostral to the substantia nigra, c-ret mRNA is not detected, whereas GDNFR-alpha is found in numerous brain structures, including the hippocampus, cortex, medial geniculate, and the medial habenula, the latter area expressing the highest levels of GDNFR-alpha mRNA in brain. These results provide evidence that c-ret and GDNFR-alpha mRNA are expressed in neuronal populations involved in motor function and provides further support for GDNF as a target-derived neurotrophic for these motor neurons. The observation that GDNFR-alpha mRNA is localized in several brain structures that do not contain detectable levels of c-ret mRNA indicates that either GDNFR-alpha utilizes signal transduction molecules other than c-ret in these areas or that other GDNF-like ligands that utilize GDNFR-alpha as a receptor may be present.

Characteristics of bombesin-induced inhibition of intake of ethanol.

The temporal and neural dependencies of the inhibitory effect of the administration of bombesin tetradecapeptide (BBS) on the intake of ethanol were assessed in the water-deprived rat. Variation of the intraperitoneal (i.p.) injection of neuropeptide--5% ethanol access interval (0-20 min), revealed that suppression induced by bombesin (0.5-4.0 micrograms/kg) was significantly greater and more potent at shorter intervals. The intake of ethanol was less in rats with subdiaphragmatic vagotomies, but bombesin equivalently suppressed the intake. Intracerebroventricular injection of bombesin more potently and completely inhibited the intake of ethanol but bombesin injected intraventricularly, unlike that given intraperitoneally, elicited excessive grooming and scratching behavior. The suppressant effect of bombesin, given intraperitoneally, requires close temporal contiguity of administration and caloric solution access, which is consistent with a satiety action of a neuropeptide. This satiation effect to ethanol of peripherally administered bombesin appears to reflect a non-vagal, extra-ventricular neural action.

Insulin-like growth factor II increases the rate of sciatic nerve regeneration in rats.

A slow rate of nerve regeneration conspires together with atrophy and degeneration of denervated organs to increase the risk of permanent disability following injury to the mammalian peripheral nervous system. Therefore, it is of both practical and theoretical interest to identify those endogenous factors that determine the spontaneous velocity of nerve regeneration, and to discover exogenous factors which hold promise for augmenting the rate. We report that locally infused insulin-like growth factor II significantly increases the speed of sensory axon regeneration in rat sciatic nerves. It appeared that 1 microgram/ml insulin-like growth factor II acted through insulin-like growth factor receptors, because a comparable concentration of insulin had little effect. Furthermore, there was a sustained reduction in regeneration rate when an anti-insulin-like growth factor II antiserum was continuously infused near a window in the epineurium located just below a site of nerve crush, indicating that the spontaneous regeneration rate was continuously dependent on endogenous insulin-like growth factor activity. These results show that exogenously administered insulin-like growth factor II can increase the rate of peripheral nerve regeneration, and that the endogenous insulin-like growth factors in nerves are required to maintain the normal rate of regeneration. These in vivo data complement previous observations showing that insulin-like growth factors can increase neurite outgrowth in cultured neurons, and that insulin-like growth factor II gene expression is correlated with synapse development. They further support the hypothesis that insulin-like growth factors play a role in nerve regeneration.

Elevated insulin-like growth factor (IGF) gene expression in sciatic nerves during IGF-supported nerve regeneration.

Nerve regeneration is augmented by neurotrophic activity, which has long been known to be increased in lesioned nerves. Of identified soluble nerve-derived neurotrophic factors, to date only insulin-like growth factors (IGFs) have been observed to increase the rate of axon regeneration in peripheral nerves. We report that IGF-I and IGF-II mRNA contents were significantly increased (P < 0.0005) distal to the site of crush in rat sciatic nerves, and decreased following axon regeneration. In transected nerves in which axon regeneration was prevented, IGF mRNAs remained elevated. IGF-I mRNAs per mg tissue were increased more in lesioned nerves than denervated muscles, whereas IGF-II mRNAs were increased more in denervated muscles than lesioned nerves. This suggested that IGF-I and IGF-II each play distinct regulatory roles during regeneration. These data bolster the hypothesis that increased IGF mRNA content in nerves supports the rate of nerve regeneration in mammals.

VIP regulation of embryonic growth.

Vasoactive intestinal peptide (VIP) plays a regulatory role in the growth of early postimplantation rodent embryos through its action on receptors localized to the central nervous system (CNS). However, the origin of the VIP influencing embryonic growth is unknown. VIP binding sites have been found prenatally; however, VIP mRNA was not detected in the rat CNS before birth and has been detected in peripheral organs only during the final third of gestation. Recent studies have revealed that VIP receptors were limited to the CNS in the embryonic day 11 (E11) rat embryo/trophoblast, which, in addition, had almost four times the VIP concentration of the E17 fetus. However, neither in situ hybridization or reverse transcriptase-polymerase chain reaction methods detected VIP mRNA in the E11 rat embryo or embryonic membranes. Rat maternal serum revealed a peak in VIP concentration at days E10-E12 of pregnancy, with VIP levels 6- to 10-fold higher than later during pregnancy. Radiolabeled VIP, administered intravenously to pregnant female mice, was found in the E10 embryo. These results suggest that VIP produced by extraembryonic tissues may regulate embryonic growth during the early postimplantation stage of development in the rodent.

Vasoactive intestinal peptide regulates embryonic growth through the action of activity-dependent neurotrophic factor.

Activity-dependent neurotrophic factor is a potent, neuroprotective protein released from astroglia by VIP and accounts in part for the neuroprotective properties of this neuropeptide. The growth-regulatory actions of VIP during embryogenesis may also occur indirectly through the release of activity-dependent neurotrophic factor. Whole cultured day-9 mouse embryos treated with activity-dependent neurotrophic factor (10(-13) M) for 4 hr grew 3.1 somites, compared with 1.6 somites in control embryos. Treated embryos appeared morphologically normal and exhibited significant increases in cross-sectional area, protein, and DNA content and bromodeoxyuridine incorporation. Anti-activity-dependent neurotrophic factor significantly inhibited growth. Co-treatment of embryos with anti-activity-dependent neurotrophic factor inhibited VIP-stimulated growth; however, anti-VIP did not inhibit activity-dependent neurotrophic factor-induced growth. These data indicate that an activity-dependent neurotrophic factor-like substance is an endogenous embryonic growth factor and that VIP-regulated growth occurs, at least in part, through activity-dependent neurotrophic factor.

A novel signaling molecule for neuropeptide action: activity-dependent neuroprotective protein.

The complete coding sequence of a novel protein (828 amino acids, pI 5.99), a potential new mediator of vasoactive intestinal peptide (VIP) activity was recently revealed. The expression of this molecule, activity-dependent neuroprotective protein (ADNP), was augmented in the presence of VIP, in cerebral cortical astrocytes. The mRNA transcripts encoding ADNP were enriched in the mouse hippocampus and cerebellum. The protein deduced sequence contained the following: (1) a unique peptide, NAPVSIPQ, sharing structural and immunological homologies with the previously reported, activity-dependent neurotrophic factor (ADNF) and exhibiting neuroprotection in vitro and in vivo; (2) a glutaredoxin active site; and (3) a classical zinc binding domain. Comparative studies suggested that the peptide, NAPVSIPQ (NAP), was more efficacious than peptides derived from ADNF. ADNP, a potential mediator of VIP-associated neuronal survival, and the new peptide, a potential lead compound for drug design, are discussed below.

Neuropeptide Y: behavioral effects in the golden hamster.

Neuropeptide Y (NPY) is found abundantly in nervous tissues of vertebrate species including the golden hamster. Centrally-administered NPY has been reported to elicit ingestive behaviors in the rat, squirrel, pig, mouse, and chick. To assess NPY's behavioral effects in a New World rodent that does not increase food intake after deprivation, NPY was injected intracerebroventricularly (10.0-0.04 micrograms/5 microliter) in home-caged golden hamsters with ad lib access to food, water and 5% w/v ethanol solution. Food and fluid intakes, and behavior displays were monitored after NPY injection. NPY promptly increased short-term food intake and observed feeding behaviors at 10.0, 3.3, 1.1, and 0.37 micrograms NPY, but there was no effect on 24 hr food intake. Water and ethanol intakes were increased only at 10.0 and 0.37 micrograms NPY, respectively. Resting behaviors decreased at NPY doses that increased feeding, but there were no consistent effects of NPY on any other category of behavior. Results demonstrate that NPY potently stimulates short-term food intake and decreases resting behavior in the golden hamster. The lack of compensatory food intake in deprived hamsters cannot be explained as an insensitivity to the putative orexigenic function of endogenous neuropeptide Y.

Bombesin-induced grooming in the golden hamster.

Lateral cerebroventricular injection of the peptide bombesin (0.01-1.0 micrograms) promptly elicited excessive grooming and scratching behaviors in home-caged male and female golden hamsters. Bombesin-induced grooming persisted throughout a 60-min observation period at doses of 0.1-1.0 micrograms. Grooming with forepaws and mouth was more consistently increased than hindleg scratching behaviors. Dependence of this neuropeptide effect on grooming on muscarinic cholinergic activity was assessed by injecting scopolamine (0.001-1 mg/kg) intraperitoneally 15 min prior to 0.1 microgram bombesin. Excessive grooming induced by centrally administered bombesin was abolished by 0.1 and 1 mg/kg scopolamine, although basal level of grooming was not significantly affected. The findings indicate a cross-species generality of the dependence of bombesin-induced grooming on muscarinic cholinergic activity, and species-specific differences among rodents in the components of excessive grooming elicited by bombesin.

Interleukin-1 alpha and vasoactive intestinal peptide: enigmatic regulation of neuronal survival.

A neurotrophic role for interleukin-1 alpha (IL-1 alpha) was investigated in dissociated spinal cord-dorsal root ganglion cultures. Three observations suggested a survival-promoting action for IL-1 alpha in nine-day-old cultures: (1) neutralizing antiserum to murine IL-1 alpha decreased neuronal survival; (2) treatment with IL-1 alpha in electrically blocked cultures increased neuronal survival; and (3) antiserum to the type I IL-1 receptor decreased neuronal survival. Treatment with VIP prevented neuronal cell death associated with the antiserum to IL-1 alpha. In contrast, treatment of one-month-old cultures with IL-1 alpha produced neuronal cell death and neutralizing antiserum to the IL-1 receptor had no effect on neuronal survival in these cultures. These experiments suggested that an IL-1-like substance was necessary for neuronal survival during a specific stage in development and that a relationship between VIP and IL-1 alpha might account in part for the neurotrophic properties of VIP. To test if VIP might be a secretagogue for IL-1, a neuron-free model system was utilized: astroglial cultures derived from cerebral cortex. VIP treatment produced a concentration-dependent (EC50: 50 pM) increase in the amount of IL-1 alpha in the medium and a decrease in cellular IL-1 alpha. Interleukin-1 beta (IL-1 beta) was also increased (EC 50: 1 nM) in the medium by VIP but without depleting IL-1 beta in the cytosol. Semi-quantitative measurements of the IL-1 alpha mRNA after VIP treatment indicated a significant but transient decrease. These data indicate that VIP produced an increase in the secretion of IL-1 alpha while depleting IL-1 alpha mRNA.

Cholinergic stimulation increases thrombin activity and gene expression in cultured mouse muscle.

Activity-dependent synapse reduction is a major determinant of neuromuscular innervation. Previous research has shown that nanomolar concentrations of hirudin, a specific thrombin antagonist, significantly attenuates this reduction, and protease nexin 1 (PN1), an endogenous thrombin inhibitor closely localized to the neuromuscular synapse, can inhibit synapse reduction at similar concentrations. Protease inhibitors which do not inhibit thrombin, including cystatin and aprotinin, had no effect on synapse reduction. We present a series of experiments examining whether prothrombin and/or PN1 gene expression, as well as thrombin activity, are regulated in muscle cultures by acetylcholine (ACh) receptor activation. We also studied the effect of exogenous thrombin on synapse elimination in co-cultures of muscle and cholinergic neurons. Cultured muscle cells were electrically blocked with tetrodotoxin (TTX), or co-treated with ACh in order to isolate ACh receptor activation. Electrical blockade resulted in a decrease in thrombin release to about two-thirds of control values. The application of ACh to electrically blocked muscle cultures resulted in a 2.5-fold increase in thrombin activity released into the medium and a 2-fold increase in prothrombin gene expression. In contrast, ACh treatment in the presence of TTX had no effect on PN1 gene expression compared to treatment with TTX alone. In addition, exogenous thrombin significantly increased synapse elimination in unstimulated muscle/cholinergic neuron co-cultures. These results suggest that thrombin or a thrombin-like molecule released from muscle is required for activity-dependent synapse elimination and is regulated by neuromuscular activity.

Activity-dependent neurotrophic factor: a potent regulator of embryonic growth and development.

Activity-dependent neurotrophic factor is a potent, neuroprotective molecule released from astroglia following stimulation by vasoactive intestinal peptide and, at least in part, accounts for the neuroprotective actions of vasoactive intestinal peptide. As well as enhancing neuronal survival, vasoactive intestinal peptide is known to regulate embryonic growth during the early postimplantation period of development. The current study was designed to assess activity-dependent neurotrophic factor's role in the growth-regulatory properties of vasoactive intestinal peptide. Treatment of whole cultured day-9 mouse embryos with activity-dependent neurotrophic factor (10(-13) M) resulted in a growth of 3.1 somites, compared with 1.6 somites in control embryos after a 4 h incubation period. Significant increases were also seen in cross-sectional area, protein and DNA content and bromodeoxyuridine incorporation. Activity-dependent neurotrophic factor-treated embryos were morphologically indistinguishable from control embryos of the same size. Anti-activity-dependent neurotrophic factor ascites significantly inhibited growth. In addition, co-treatment of embryos with anti-activity-dependent neurotrophic factor ascites inhibited vasoactive intestinal peptide-stimulated growth. Although anti-vasoactive intestinal peptide treatment inhibited growth, it did not inhibit activity-dependent neurotrophic factor-induced growth. These data indicate that an activity-dependent neurotrophic factor-like substance is an endogenous and potent growth-promoting factor in the early postimplantation embryo and that vasoactive intestinal peptide-regulated growth of embryos occurs, at least in part, through the action of activity-dependent neurotrophic factor.

Vasoactive intestinal peptide: behavioral effects in the rat and hamster.

The behavioral effects of intracerebroventricular (ICV) injection of the brain-gut peptide vasoactive intestinal peptide (VIP) were quantified with a behavioral sampling technique in home-caged, nondeprived, male and female albino rats and golden hamsters. ICV VIP sex-dependently decreased observed resting behavior during 1 hr after injections in both rats and hamsters at 0.1-10.0 micrograms. Grooming behavior was increased in hamsters, and rearing and standing behaviors were increased in rats, sex-dependently at VIP doses that decreased resting. Drinking behavior was suppressed in rats by VIP at 10.0 micrograms. Intraperitoneal (IP) VIP (100.0 micrograms/kg) increased 5% ethanol intake and decreased eating behavior in fluid-deprived male rats. The increase in ethanol intake produced by IP VIP was prevented by IP cholecystokinin octapeptide (CCK, 4.0 micrograms/kg). VIP potently controls resting and ingestive behaviors, suggesting a role for this neuropeptide, along with CCK, in the feedback regulation of rodent behavior.

Effect of bombesin on behaviors associated with ethanol satiation and blood ethanol levels.

The behavioral specificity and physiological significance of bombesin-induced inhibition of ethanol intake were assessed in water-deprived rats. The behavioral display accompanying suppression of 5% ethanol intake by bombesin tetradecapeptide (BBS-14, 1-4 micrograms/kg) was measured with an instantaneous time-sampling technique. Blood ethanol levels were measured after peripheral BBS-14 and bombesin nonapeptide (BBS-9) administration, and after either oral self-administration or peripheral injection of ethanol. The display accompanying BBS-14-reduced ethanol consumption differed from control in that less drinking and feeding behaviors were observed and resting increased, dose-dependently. The typical behavioral sequence of ethanol satiation was observed in all conditions. Both BBS-14 and -9 reduced blood ethanol levels when oral intake was suppressed, and BBS-14 did not affect blood ethanol levels or elimination rate when ethanol was injected. The results are compatible with an hypothesis of a functional role for endogenous bombesin-like peptides and receptors in a neuropeptide control of ethanol intake and energy balance.

Normalization of NF-κB activity in dorsal root ganglia neurons cultured from diabetic rats reverses neuropathy-linked markers of cellular pathology.

AIMS/HYPOTHESIS: Dorsal root ganglia (DRG) sensory neurons cultured from 3 to 5 month streptozotocin (STZ)-induced diabetic rats exhibit structural and biochemical changes seen in peripheral nerve fibers in vivo, including axonal swellings, oxidative damage, reduced axonal sprouting, and decreased NF-κB activity. NF-κB is a transcription factor required by DRG neurons for survival and plasticity, and regulates transcription of antioxidant proteins (e.g. MnSOD). We hypothesized that the diabetes-induced decrease in NF-κB activity in DRG contributes to pathological phenomena observed in cultured DRG neurons from diabetic rats. METHODS: NF-κB localization was assessed in intact DRG and neuron cultures using immunostaining. NF-κB activity was manipulated in sensory neuron cultures derived from age-matched normal or 3-5 month STZ-diabetic rats using pharmacological means and lentiviral expression of shRNA. The impact of diabetes and altered NF-κB activity on neuronal phenotype involved analysis of neurite outgrowth, neurite morphology, oxidative stress (lipid peroxidation) and expression of MnSOD. RESULTS: STZ-induced diabetes caused a significant decrease in nuclear localization of NF-κB subunits p50 and c-rel, but no change in p65 in intact DRG. Inhibition of NF-κB in normal neuron cultures significantly increased axonal swellings and oxidative stress, and reduced both neurite outgrowth and expression of MnSOD. These phenomena mimicked markers of pathology in cultured DRG neurons from diabetic rats. Enhancement of NF-κB activity in cultured diabetic DRG neurons ameliorated the sub-optimal neurite outgrowth and MnSOD levels triggered by diabetes. Exogenous insulin enhanced nuclear localization of p50 and c-rel but not p65 in diabetic neuronal cultures. CONCLUSION/INTERPRETATION: The diabetes-induced decrease of nuclear localization of NF-κB subunits p50 and c-rel in DRG contributes to development of in vitro markers of peripheral neuropathy, possibly through impaired mitochondrial ROS scavenging by deficient MnSOD.

Evidence for the involvement of calbindin D28k in the presenilin 1 model of Alzheimer's disease.

Pathological hallmarks of Alzheimer's disease include memory deficits, accumulation of amyloid beta (Abeta) plaques, the appearance of neurofibrillary tangles, and dysregulation of calcium homeostasis, which has been linked to mutations in the presenilin gene that code for presenilin (PS) proteins. PSs are a family of multi-pass transmembrane proteins where normal presenilins (PS1 and PS2) are highly localized in the endoplasmic reticulum (ER). Several past studies have explored alterations in long-term potentiation (LTP), a proposed molecular correlate of memory, and in behavioral tests of spatial memory in a variety of PS1 models. These reports suggest that calcium plays a role in these alterations, but mechanistic explanations for changes in LTP and in behavioral tests of memory are still lacking. To test the hypothesis that calcium-related mechanisms, such as changes in calcium buffering, are associated with alterations in LTP and memory, we utilized in vitro experimental paradigms of LTP in hippocampal slices obtained from the PS1-M146V transgenic mouse model of Alzheimer's disease (AD). We also used the in vivo Morris water maze (MWM), a test for hippocampal dependent spatial memory. In addition, we used cellular assays to explore molecular mechanisms. We confirm that PS1 mutations (M146V) enhance LTP. We also find increases in some parameters of the MWM, and alterations in other parameters, such as path length indicating impairment in cognitive functioning in PS1-M146V mice. In addition, these findings are observed in association with increased calbindin D28K expression in the CA1 hippocampus of PS1-M146V mice.