Baseline and changes in serum uric acid independently predict 11-year incidence of metabolic syndrome among community-dwelling women

INTRODUCTION

Metabolic syndrome (MetS) is associated with an increased risk of major cardiovascular events. In women, increased serum uric acid (SUA) levels are associated with MetS and its components. However, whether baseline and changes in SUA predict incidence of MetS and its components remains unclear.

METHODS

The subjects comprised 407 women aged 71 ± 8 years from a rural village. We have identified participants who underwent a similar examination 11 years ago, and examined the relationship between baseline and changes in SUA, and MetS based on the modified criteria of the National Cholesterol Education Program's Adult Treatment Panel (NCEP-ATP) III report.

RESULTS

Of these subjects, 83 (20.4%) women at baseline and 190 (46.7%) women at follow-up had MetS. Multiple linear regression analysis was performed to evaluate the contribution of each confounding factor for MetS; both baseline and changes in SUA as well as history of cardiovascular disease, low-density lipoprotein cholesterol, and estimated glomerular filtration ratio (eGFR) were independently and significantly associated with the number of MetS components during an 11-year follow-up. The adjusted odds ratios (ORs) (95% confidence interval) for incident MetS across tertiles of baseline SUA and changes in SUA were 1.00, 1.47 (0.82-2.65), and 3.11 (1.66-5.83), and 1.00, 1.88 (1.03-3.40), and 2.49 (1.38-4.47), respectively. In addition, the combined effect between increased baseline and changes in SUA was also a significant and independent determinant for the accumulation of MetS components (F = 20.29, p < 0.001). The ORs for incident MetS were significant only in subjects with age ≥ 55 years, decline in eGFR, and no baseline MetS.

CONCLUSIONS

These results suggested that combined assessment of baseline and changes in SUA levels provides increased information for incident MetS, independent of other confounding factors in community-dwelling women.

Interaction between gender and uric acid on hemoglobin A1c in community-dwelling persons

INTRODUCTION

Higher glycated hemoglobin (Hb) (HbA1c) is significantly associated with an increased risk of cardiovascular disease (CVD). Serum uric acid (SUA) levels are associated with glucose intolerance and type 2 diabetes. Whether gender-specific differences regarding the relationship between SUA levels and HbA1c exist is unknown.

AIM

We recruited 1636 (men, 696 aged of 70 ± 10 years; women, 940 aged of 70 ± 9 years) participants and enrolled in the study during their annual health examination from a single community. We investigated the association between SUA levels and HbA1c within each gender.

RESULTS

Multiple linear regression analysis showed that in men, SUA (β = -0.091, p = 0.014) with prevalence of antidiabetic medication (β = 0.428, p < 0.001) and eGFR (β = 0.112, p = 0.016) were significantly and negatively associated with HbA1c, and in women, SUA (β = 0.101, p = 0.002) with prevalence of antidiabetic medication (β = 0.458, p < 0.001) were significantly and positively associated with HbA1c. Moreover, the interaction between gender and SUA (β = 0.445, p < 0.001) as well as gender (β = -0.465, p < 0.001), prevalence of antidiabetic medication (β = 0.444, p < 0.001), eGFR_CKDEPI (β = 0.074, p = 0.014), and SUA (β = -0.356, p < 0.001) was a significant and independent determinant of HbA1c. A significant interactive effect of gender and SUA on determinants of HbA1c was noted in patients not on antidiabetic medications, regardless of age, HbA1c, and renal function.

CONCLUSIONS

The interaction between gender and SUA was associated with HbA1c independent of other metabolic factors in community-dwelling persons.

Contribution of the Runx1 transcription factor to axonal pathfinding and muscle innervation by hypoglossal motoneurons

The runt-related transcription factor Runx1 contributes to cell type specification and axonal targeting projections of the nociceptive dorsal root ganglion neurons. Runx1 is also expressed in the central nervous system, but little is known of its functions in brain development. At mouse embryonic day (E) 17.5, Runx1-positive neurons were detected in the ventrocaudal subdivision of the hypoglossal nucleus. Runx1-positive neurons lacked calcitonin gene-related peptide (CGRP) expression, whereas Runx1-negative neurons expressed CGRP. Expression of CGRP was not changed in Runx1-deficient mice at E17.5, suggesting that Runx1 alone does not suppress CGRP expression. Hypoglossal axon projections to the intrinsic vertical (V) and transverse (T) tongue muscles were sparser in Runx1-deficient mice at E17.5 compared to age-matched wild-type littermates. Concomitantly, vesicular acetylcholine transporter-positive axon terminals and acetylcholine receptor clusters were less dense in the V and T tongue muscles of Runx1-deficient mice. These abnormalities in axonal projection were not caused by a reduction in the total number hypoglossal neurons, failed synaptogenesis, or tongue muscles deficits. Our results implicate Runx1 in the targeting of ventrocaudal hypoglossal axons to specific tongue muscles. However, Runx1 deficiency did not alter neuronal survival or the expression of multiple motoneuron markers as in other neuronal populations. Thus, Runx1 appears to have distinct developmental functions in different brain regions.

Serotonin 2A receptor regulates microtubule assembly and induces dynamics of dendritic growth cones in rat cortical neurons in vitro

Serotonin (5-HT) regulates the development of cerebral cortex, but 5-HT receptors mediating the effects are poorly understood. We investigated roles of 5-HT2A receptor in dendritic growth cones using dissociation culture of rat cerebral cortex. Neurons at embryonic day 16 were cultured for 4 days and treated with 5-HT2A/2C receptor agonist (DOI) for 4h. DOI increased the size of growth cone periphery which was actin-rich and microtubule-associated protein 2-negative at the dendritic tip. The length increase of the growth cone periphery may be mediated by 5-HT2A receptor, because the 5-HT2A receptor antagonist reversed the effects of DOI. Moreover, the time-lapse analysis demonstrated the increase of morphological dynamics in dendritic growth cones by DOI. Next, to elucidate the mechanisms underlying the actions of 5-HT2A receptor in dendritic growth cones, we examined the cytoskeletal proteins, tyrosinated α-tubulin (Tyr-T; dynamic tubulin) and acetylated α-tubulin (Ace-T; stable tubulin). DOI increased the fluorescence intensity of Tyr-T, while decreased that of Ace-T in the dendritic growth cone periphery. These effects were reversed by the 5-HT2A receptor antagonist, suggesting that 5-HT2A receptor promotes microtubule dynamics. In summary, it was suggested that 5-HT2A receptor induces morphological changes and dynamics of dendritic growth cones through regulation of microtubule assembly.

Coexpression of Runx1 and Runx3 in mechanoreceptive dorsal root ganglion neurons

Runt-related transcription factors (Runx) regulate the development of various cells. It has been reported that Runx1 and Runx3 are expressed in distinct subpopulations of primary sensory neurons in the dorsal root ganglion (DRG), and play important roles in the differentiation of nociceptive and proprioceptive neurons, respectively. In the present study, we examined the developmental changes of the expression of Runx1 and Runx3 in the mouse DRG during embryonic and postnatal stages. We found that the expression of Runx3 preceded that of Runx1, but dramatically decreased before birth, whereas the Runx1 expression was maintained during postnatal periods. These results suggest that roles of Runx1 and Runx3 may change dynamically in the differentiation and maturation of DRG neurons. In addition, several DRG neurons expressed both Runx1 and Runx3 throughout embryonic and postnatal stages and many Runx3-expressing DRG neurons coexpressed Runx1 at postnatal day 28. Double and triple labeling studies suggest that some of the Runx1/Runx3-double expressing neurons coexpressed TrkB, c-ret, and TrkC, which have been shown in the mechanoreceptive DRG neurons. These results suggest that Runx1/Runx3-double expressing neurons may represent mechanoreceptive properties in the DRG.

Receptor-dependent regulation of dendrite formation of noradrenaline and dopamine in non-GABAergic cerebral cortical neurons

The present study characterized the receptor-dependent regulation of dendrite formation of noradrenaline (NA) and dopamine (DA) in cultured neurons obtained from embryonic day 16 rat cerebral cortex. Morphological diversity of cortical dendrites was analyzed on various features: dendrite initiation, dendrite outgrowth, and dendrite branching. Using a combination of immunocytochemical markers of dendrites and GABAergic neurons, we focused on the dendrite morphology of non-GABAergic neurons. Our results showed that (1) NA inhibited the dendrite branching, (2) β adrenergic receptor (β-AR) agonist inhibited the dendrite initiation, while promoted the dendrite outgrowth, (3) β1-AR and β2-AR were present in all the cultured neurons, and both agonists inhibited the dendrite initiation, while only β1-AR agonist induced the dendrite branching; (4) DA inhibited the dendrite outgrowth, (5) D1 receptor agonist inhibited the dendrite initiation, while promoted the dendrite branching. In conclusion, this study compared the effects of NA, DA and their receptors and showed that NA and DA regulate different features on the dendrite formation of non-GABAergic cortical neurons, depending on the receptors.

Differential roles of calcitonin family peptides in the dendrite formation and spinogenesis of the cerebral cortex in vitro

We examined roles of calcitonin family peptides in the initial stages of dendrite formation and the maturation of dendritic spines in the rat cerebral cortex in vitro. Embryonic day 18 cortical neurons were dissociated and cultured for 2-3days in the presence of calcitonin gene-related peptide (CGRP), calcitonin, amylin or adrenomedullin. The treatment of cortical neurons with CGRP promoted the formation of primary dendrites of non-GABAergic neurons. In contrast, the treatment with amylin and adrenomedullin for 3days inhibited the dendritic elongation of non-GABAergic neurons. Calcitonin had no effect on the initial dendrite formation. Next, we examined roles of the peptides in the spine formation. Embryonic day 16 cortical neurons were cultured for 14days and then treated acutely with CGRP, amylin or adrenomedullin for 24h. The density of filopodia, puncta/stubby spines and spines were increased by the CGRP treatment, whereas decreased by amylin. Therefore, CGRP and amylin showed opposite effects on the formation of dendritic filopodia, puncta and spines. Adrenomedullin had no effects on the spine formation. In conclusion, the present study showed that calcitonin family peptides have differential effects both in the dendrite formation during the initial stages and the spine formation of cortical neurons in vitro.

Subtype specific roles of serotonin receptors in the spine formation of cortical neurons in vitro

Dendritic spines are postsynaptic structures which are formed from filopodia. We examined roles of serotonin (5-HT) receptors in the spine formation. Embryonic rat cortical neurons were cultured for 10 or 14 days and treated by 5-HT receptor agonists for 24 h. At 11 days in vitro, 5-HT(1A) agonist increased filopodia density, whereas 5-HT(2A/2C) agonist increased the density of puncta and spines. At 15 days in vitro, 5-HT(1A) agonist decreased the density of puncta and spines, whereas 5-HT(2A/2C) agonist decreased filopodia density with increase of spines. In conclusion, the present study shows 5-HT receptors have subtype-specific effects on the spine formation.

Characterization of sensory neurons in the dorsal root ganglia of Bax-deficient mice

During development, the rescue of spinal motoneurons as well as sensory neurons in the dorsal root ganglion (DRG) from programmed cell death (PCD) depends on the integrity of peripheral target innervation. Following deletion of the pro-apoptotic gene Bax, both motoneurons and DRG neurons are rescued from PCD. In the present paper, we asked whether different cell types in the DRG exhibit distinct responses to Bax deletion. In 1-month-old Bax-deficient (Bax-/-) mice, distinct subsets of DRG neurons that were immunopositive for TrkA, CGRP, TRPV1 or TrkC, were all increased in number and exhibited cell atrophy compared to wild type DRG neurons. In addition there was hyperinnervation of the epidermis by CGRP immunopositive processes and a correlated functional hypersensitivity of mechanical nociception in Bax-/- mice. By contrast, the functional properties of populations of rescued thermoreceptor and mechanoreceptor DRG neurons were unchanged. These data indicate that although Bax deletion rescues all of the DRG cell types examined here from PCD, the functional consequences of having excess cells differ between sensory phenotypes.

Runx3 is required for the specification of TrkC-expressing mechanoreceptive trigeminal ganglion neurons

Sensory neurons project axons to specific peripheral and central targets according to their sensory modality. Runx3 is crucially involved in proprioceptive dorsal root ganglion neuron development. Runx3 is also expressed in trigeminal ganglion (TG) neurons. The role of Runx3 in the TG, however, is largely unknown because the TG does not contain proprioceptive neurons. In Runx3-deficient (Runx3(-/-)) mice, TrkB-expressing TG neurons were increased, whereas TrkC-expressing TG neurons were decreased during TG neuron development. In Runx3(-/-) neonatal mice, TrkC-expressing TG neurons did not project to the Merkel cells in the outer root sheath (ORS) of whisker vibrissae peripherally and the spinal trigeminal nucleus pars interpolaris (Sp5I) centrally. These findings suggest that Runx3 is required for the specification of TrkC-expressing TG neurons, conveying mechanoreceptive signals from the Merkel cells in the ORS of the whisker vibrissae to the Sp5I.

Validation of a single-channel airflow monitor for screening of sleep-disordered breathing

A simple screening method for sleep-disordered breathing (SDB) is desirable for primary care practices. In the present study, a simple monitor, which utilises a new type of flow sensor and a novel algorithm, was prospectively validated. Home recording for 2 nights with the monitor only, followed by in-laboratory recording with the monitor together with polysomnography, were carried out in consecutive patients (n = 100) suspected of SDB. A subjective sleep log was also recorded. The signal was analysed using power spectral analysis, which yielded the flow respiratory disturbance index (flow-RDI). There was no recording failure at home. The reproducibility of the flow-RDI between the 2 nights at home was high (intraclass correlation coefficient = 0.92). The sensitivity and specificity of the in-laboratory flow-RDI to diagnose SDB were 0.96 and 0.82, 0.91 and 0.82, and 0.89 and 0.96, for apnoea/hypopnoea index (AHI) > or =5, > or =15 and > or =30 events x h(-1), respectively. The diagnostic ability in low-severity subgroups (female, normal weight, AHI <15 events x h(-1)) was almost comparable to that in the entire group. Excluding subjective waking time on the sleep log from the recording time had no significant effect on the flow-RDI. The single-channel monitor is considered feasible for ambulatory sleep disordered breathing monitoring because of its easy applicability, high reproducibility and relatively high agreement with polysomnography results.

Dynamic regulation of the expression of neurotrophin receptors by Runx3

Sensory neurons in the dorsal root ganglion (DRG) specifically project axons to central and peripheral targets according to their sensory modality. However, the molecular mechanisms that govern sensory neuron differentiation and the axonal projections remain unclear. The Runt-related transcription factors, Runx1 and Runx3, are expressed in DRG neuronal subpopulations, suggesting that they might regulate the cell specification and the trajectories of specific axons. Here, we show that parvalbumin-positive DRG neurons fail to differentiate from the onset in Runx3(-/-) mice. By contrast, TrkC-positive DRG neurons differentiate normally at embryonic day (E) 11.5, but disappear by E13.5 in Runx3(-/-) mice. Subsequently, TrkC-positive DRG neurons reappear but in smaller numbers than in the wild type. In Runx3(-/-) mice, central axons of the TrkC-positive DRG neurons project to the dorsal spinal cord but not to the ventral and intermediate spinal cord, whereas the peripheral axons project to skin but not to muscle. These results suggest that Runx3 controls the acquisition of distinct proprioceptive DRG neuron identities, and that TrkC-positive DRG neurons consist of two subpopulations: Runx3-dependent early-appearing proprioceptive neurons that project to the ventral and intermediate spinal cord and muscle; and Runx3-independent late-appearing cutaneous neurons that project to the dorsal spinal cord and skin. Moreover, we show that the number of TrkA-positive DRG neurons is reduced in Runx3(-/-) mice, as compared with the wild type. These results suggest that Runx3 positively regulates the expression of TrkC and TrkA in DRG neurons.

Runx1 selectively regulates cell fate specification and axonal projections of dorsal root ganglion neurons

Runx1-deficient mice die around embryonic day 11.5 due to impaired hematopoiesis. This early death prevents the analysis of the role of Runx1 in the development of sensory ganglia. To overcome the early embryonic lethality, we adopted a new approach to utilize transgenic Runx1-deficient mice in which hematopoietic cells are selectively rescued by Runx1 expression under the control of GATA-1 promoter. In Runx1-deficient mice, the total number of dorsal root ganglion (DRG) neurons was increased, probably because of an increased proliferative activity of DRG progenitor cells and decreased apoptosis. In the mutant DRG, TrkA-positive neurons and peptidergic neurons were increased, while c-ret-positive neurons were decreased. Axonal projections were also altered, in that both central and peripheral projections of CGRP-positive axons were increased. In the dorsal horn of the spinal cord, projections of CGRP-positive axons expanded to the deeper layer, IIi, from the normal terminal area, I/IIo. Our results suggest that Runx1 is involved in the cell fate specification of cutaneous neurons, as well as their projections to central and peripheral targets.

[Infection control in neutropenia induced by high-dose cytarabine chemotherapy]

A high-dose cytarabine (Cylocide; Ara-C: HDAC) chemotherapy has been successfully used as a postremission consolidation therapy for acute myeloid leukemia (AML). Although this chemotherapy has been estimated to cause severe myelosuppression, there has been no report about infection risk relating to HDAC chemotherapy. The purpose of this retrospective study is to evaluate the infection risk in AML patients treated with HDAC (n = 18) compared to those treated with standard-dose Ara-C (SDAC, n = 18). The mean duration of severe neutropenia (neutrophils < 500/microl) in HDAC group and SDAC was 14.8 days and 10.4 days, respectively, indicating a significant prolongation in the HDAC group (p < 0.05). The frequency of febrile neutropenia in the HDAC group tended to increase compared to that in the SDAC group (p = 0.093). The average days of usage of quinolone antimicrobial prophylaxis and aminoglycoside antibiotic injection in febrile neutropenia in the HDAC group were significantly longer than those of the SDAC group (quinolone; p < 0.01, aminoglycoside; p < 0.05). The frequency of Streptococcus infection isolated from pharyngeal mucus in the HDAC group was significantly higher than that in the SDAC group (100% versus 75%; p < 0.05). These results suggest that HDAC chemotherapy increased the infection risk compared to SDAC, and especially patients who received HDAC need a further prevention plan against gram-positive bacteria.

Genomic organization and transcripts of the zebrafish Protocadherin genes

We have examined the protocadherin (Pcdh) gene clusters of the zebrafish (Danio rerio). At least three sets of the Pcdh gene cluster were found in the zebrafish genome. Here, we describe the complete organization of the DrPcdh2 gene clusters. Classification by phylogenetic and transcript analyses revealed 7 DrPcdh2omicron, 20 DrPcdh2alphaa, 12 DrPcdh2alphab, and 1 DrPcdh2alphac variable exons upstream of the DrPcdh2alpha constant region exons in the DrPcdh2 gene cluster. The constant regions of the DrPcdh1alpha and DrPcdh2alpha genes in zebrafish were orthologs of those of the mammalian Pcdhalpha. These exons all encoded plural PXXP motifs in their cytoplasmic tails. The sequences of the variable exons were highly conserved within each family: DrPcdh2omicron, DrPcdh2alphaa, and DrPcdh2alphab. Transcript analysis revealed that zebrafish Pcdhs had alternatively spliced variants in the constant region that were not found in mammals. More gene clusters, more variable exons, and more alternative splicing variants were found in zebrafish than in mammals. Thus, although the Pcdhalpha families were common to diverse vertebrates, their gene number, structure, and transcripts were different between teleosts and mammals.

Cadherin-related neuronal receptor 1 (CNR1) has cell adhesion activity with β1 integrin mediated through the RGD site of CNR1

Cadherin-related neuronal receptor (CNR) proteins are a diverse set of synaptic protocadherins, but little is known about its adhesive properties. We found that overexpressed CNR1 protein localized on the cell surface of HEK293T cells and increased the calcium-dependent cell aggregation potential. However, we could not detect the strong homophilic binding activity of CNR1 EC-Fc fusion protein in vitro. Parental HEK293T cells adhered to Arg-Gly-Asp (RGD) motif of EC1 domain of CNR1-Fc fusion protein. The fusion protein that the Asp73 of EC1 point-mutated to Glu (RGE-Fc) lost the adhesive activity. The adhesion activity of HEK293T cells to CNR1 EC-Fc fusion protein was completely blocked by inhibitors of integrins, including RGDS peptide and anti-beta1 integrin antibodies. The increased cell-aggregative property of CNR1 transfectants was also blocked by RGDS peptides. At cell-cell junctions of the CNR1 transfectants, co-localization between CNR1 and HEK293T endogenous beta1 integrin was observed. Furthermore, the spatiotemporal expression patterns of CNR and beta1 integrin nearly overlapped in the molecular layer of the developing mouse cerebellum in the main stage of synaptogenesis. These results indicate that CNR1 has a heterophilic, calcium-dependent cell adhesion activity with the beta1 integrin subfamily, and raise the possibility of CNR-beta1 integrin association in synaptogenesis.

Two novel CNRs from the CNR gene cluster have molecular features distinct from those of CNR1 to 8

Cadherin-related neuronal receptor (CNR) family proteins are known as synaptic cadherins and Reelin receptors. Here we have identified two novel mouse CNR genes, CNRc1 and CNRc2, orthologues of human protocadherin (Pcdh) alpha-c1 and Pcdhalpha-c2, respectively. While the variable large exons of CNRc1 and c2 contain six conserved extracellular cadherin repeats (EC1-6) and are linked to the constant exons, both contain several molecular features distinct from CNR1-8. CNRc1 and c2 lack the Arg-Gly-Asp (RGD) sequence that is conserved in the EC1 of CNR1-8, which is necessary for binding to Reelin. The present studies confirm that CNRc1 and c2 failed to immunoprecipitate with Reelin. In addition, the regulation of novel CNR expression patterns during brain development is slightly different from that of CNR1. The identification of these new CNR genes characterized by their distinct extracellular function and expression is indicative of the novel diversity of the processes of brain structuring and synapse regulation.

Involvement of nitric oxide in pentylenetetrazole-induced kindling in rats

We investigated the role of nitric oxide (NO) and brain-derived neurotrophic factor (BDNF) in the pentylenetetrazole (PTZ)-induced kindling in rats. Seizures were induced by single administration of PTZ, which was associated with an increase in levels of NO metabolites (NOx) in the hippocampus. Pretreatment with a neuronal NO synthase inhibitor, 7-nitroindazole (7-NI), diminished the PTZ-induced increase in NOx levels without affecting the seizure intensity. Repeated administration of PTZ produced a gradual increase in the seizure intensity, leading to the development of kindling. In the kindled rats, PTZ at a dose of 40 mg/kg increased NOx levels in the hippocampus, whereas it had no effect in control animals. Cotreatment of 7-NI with PTZ blocked the development of kindling and attenuated the PTZ-induced increase in NOx levels. A significant increase in BDNF levels was observed in the hippocampus of the kindled rats, which returned to the control levels following seizures induced by PTZ. 7-NI reduced the hippocampal BDNF levels in control rats and suppressed the increase of BDNF levels in the kindled rats. Our findings suggest that NO plays a role in the development of PTZ-induced kindling and that BDNF may contribute to the NO-dependent plastic changes in neuronal excitability.

Proteins of the CNR family are multiple receptors for Reelin

Layering and positioning of neurons require Reelin- and Src family-associated mammalian Disabled (mDab1). Cadherin-related neuronal receptor (CNR) genes are expressed in neurons of the cortical layer, but not in Cajal-Retzius cells expressing Reelin. This leads us to hypothesize that CNRs bound to Fyn of the Src family are receptors for Reelin. Herein we confirm the association and colocalization of CNR proteins with Reelin. This binding is blocked by CR-50 antibody against Reelin, as well as by monoclonal antibodies produced against CNRs. Both disturb the signaling pathway from Reelin to mDab1 and the positioning of cortical neurons in vitro. These results strongly suggest that the CNR family proteins are multiple Reelin receptors. In addition, differential conservation of the Reelin-binding domain among terrestrial vertebrates may be pertinent to the diversity or complexity of brains.

Long-term deprivation of oestrogens by ovariectomy potentiates beta-amyloid-induced working memory deficits in rats

1 In the present study, we examined whether deprivation of oestrogens by ovariectomy could modify learning and memory deficits caused by a continuous intracerebroventricular (i.c.v.) infusion of amyloid beta-peptide (Abeta), the major constituent of senile plaques in AD. 2 Neither long-term (3 months) nor short-term (1 month), deprivation of oestrogens by ovariectomy caused a significant impairment in spatial learning and memory in a water maze and spontaneous alternation behaviour in a Y-maze. 3 A continuous i.c.v. infusion of Abeta-(1-42) caused spatial learning and memory deficits in both ovariectomized and sham-operated rats. 4 The Abeta-induced working memory deficits were significantly potentiated in ovariectomized rats compared with sham-operated rats when mnemonic ability was examined 3 months after ovariectomy. 5 These results suggest that long-term deprivation of oestrogens induced by ovariectomy increases susceptibility to memory deficits produced by Abeta-(1-42) in rats.

Protective effects of idebenone and alpha-tocopherol on beta-amyloid-(1-42)-induced learning and memory deficits in rats: implication of oxidative stress in beta-amyloid-induced neurotoxicity in vivo

Amyloid beta-peptide (A beta), the major constituent of the senile plaques in the brains of patients with Alzheimer's disease, is cytotoxic to neurons and has a central role in the pathogenesis of the disease. Previous studies have suggested that oxidative stress is involved in the mechanisms of A beta-induced neurotoxicity in vitro. In the present study, we examined whether oxidative stress contributes to learning and memory deficits caused by continuous intracerebroventricular infusion of A beta-(1-42). In the A beta-(1-42)-infused rats, spontaneous alternation behaviour in a Y-maze and spatial memory in a water maze task were significantly impaired, as compared with A beta-(40-1)-infused control rats. The retention of passive avoidance learning was also significantly impaired by treatment with A beta-(1-42). Potent antioxidants idebenone and alpha-tocopherol prevented the behavioural deficits in Y-maze and water maze, but not passive avoidance, tasks in A beta-(1-42)-infused rats when they were repeatedly administered by mouth once a day from 3 days before the start of A beta infusion to the end of behavioural experiments. Lipid peroxide levels in the hippocampus and cerebral cortex of A beta-(1-42)-infused rats did not differ from those in control animals, and neither idebenone nor alpha-tocopherol affected the lipid peroxide levels. These results suggest that treatment with antioxidants such as idebenone and alpha-tocopherol prevents learning and memory deficits caused by A beta.

Brain dysfunction associated with an induction of nitric oxide synthase following an intracerebral injection of lipopolysaccharide in rats

We investigated the pathophysiological role of nitric oxide synthesized by inducible nitric oxide synthase in the brain, by injecting lipopolysaccharide directly into the rat cerebral cortex/hippocampus. The levels of nitric oxide metabolites, nitrite and nitrate, began to increase in a dose-dependent manner with a 3-h lag, and reached approximately seven-fold the basal levels 8 h after the direct injection of lipopolysaccharide (5 microg). The lipopolysaccharide-induced increase in nitrite and nitrate levels was inhibited by treatment with the specific inducible nitric oxide synthase inhibitor aminoguanidine. The protein synthesis inhibitor cycloheximide delayed the onset of the increase in nitric oxide metabolite levels, and reduced the peak levels. Lipopolysaccharide increased Ca2+-independent, but not Ca2+-dependent, nitric oxide synthase activity in the brain. Intense nicotinamide adenine dinucleotide phosphate-diaphorase activity was observed in round cells in the vicinity of the site of injection of lipopolysaccharide 8 h after the injection. Neuronal death was observed seven days after the injection of lipopolysaccharide. Spatial memory, as assessed by performance in a water maze task and spontaneous alternation behavior in a Y-maze, was significantly impaired in rats which had had previous bilateral injections of lipopolysaccharide into the hippocampus. The lipopolysaccharide-induced neuronal death and spatial memory impairments were prevented by aminoguanidine. These results suggest that direct injection of lipopolysaccharide into the brain causes an induction of inducible nitric oxide synthase in vivo. Furthermore, it is suggested that nitric oxide produced by inducible nitric oxide synthase is responsible for the lipopolysaccharide-induced brain dysfunction.

Serotonin2A receptor-like immunoreactivity in rat cerebellar Purkinje cells

In the present study we examined the distribution pattern of serotonin2A (5-HT2A) receptors in the rat cerebellum. A strong immunoreaction against 5-HT2A receptor protein was observed in Purkinje cells. A dense cluster of immunopositive dendritic profiles of Purkinje cells was located beneath the pia matter of cerebellar cortex. Somal profiles in the cerebellar nuclei had weak to moderate immunoreactions.

NC-1900, an active fragment analog of arginine vasopressin, improves learning and memory deficits induced by beta-amyloid protein in rats

We have reported that the continuous infusion of beta-amyloid protein-(1-40) into the rat cerebral ventricle produces learning and memory deficits accompanied by dysfunction in the cholinergic and dopaminergic systems. L-Pyroglutamyl-L-asparaginyl-L-seryl-L-prolyl-L-arginylglycinamide (NC-1900), an active fragment analog of arginine vasopressin in the rat brain, is a stable peptide with a five-fold longer half-life than that of arginine vasopressin-(4-9). In the present study, we examined the effects of NC-1900 on learning and memory deficits in beta-amyloid protein-(1-40)-infused rats. The rats were injected subcutaneously with NC-1900 (0.1 and 1 ng kg(-1)) once a day throughout the period of behavioral examination. In the beta-amyloid protein-infused rats, learning and memory in water maze and passive avoidance tasks were impaired compared with these in the control rats. NC-1900 prevented the learning and memory deficits in beta-amyloid protein-infused rats. Moreover, NC-1900 tended to increase the choline acetyltransferase activity in the frontal cortex of the beta-amyloid protein-infused rats. These results suggested that NC-1900 could be useful for the treatment of patients with Alzheimer's disease.

The cellular localization of 5-HT2A receptors in the spinal cord and spinal ganglia of the adult rat

The localization of serotonin2A (5-HT2A) receptors in the adult rat spinal cord and dorsal root ganglia was examined by using a polyclonal antibody that recognizes the C-terminus peptides of the mouse 5-HT2A receptor. Positive cell bodies of 5-HT2A receptor were found in several regions of the spinal cord. Generally, large-to-intermediate sized neuronal cell bodies were intensely immunolabeled. Motoneurons in the ventral horn were the most intensely labeled. Dot-like immunoreactive profiles were located beneath the cell membrane of motoneurons. Neuronal somata in the intermediolateral nucleus of the thoracic spinal cord were moderately labeled. The immunoreactivity in the dorsal horn was weak. A considerable number of glial cell bodies in the white matter were immunostained. The majority of both small and large sized neurons were 5-HT2A immunopositive in the dorsal root ganglion.

Difference of (Ca2+)i movements in platelets stimulated by thrombin and TRAP: the involvement of alpha(IIb)beta3-mediated TXA2 synthesis

This study investigated the difference of [Ca2+]i movement in platelets in response to thrombin and TRAP. The involvement of alpha(IIb)beta3 in this signaling was also studied. Stimulation of platelets with thrombin at 0.03 U/ml caused platelet aggregation and a two-peak increase in [Ca2+]i. The second peak of [Ca2+]i, but not the first peak was abolished by the inhibition of platelet aggregation with alpha(IIb)beta3 antagonists or by scavenging endogenous ADP with apyrase. A cyclooxygenase inhibitor, aspirin, and a TXA2 receptor antagonist, BM 13505, also abolished the second peak of [Ca2+]i but not the first peak, although these regents did not inhibit aggregation. Under the same assay conditions, measurement of TXB2 demonstrated that alpha(IIb)beta3 antagonists and aspirin almost completely inhibited the production of TXB2. In contrast to thrombin-stimulation, TRAP caused only a single peak of [Ca2+]i even in the presence of platelet aggregation, and a high level of [Ca2+]i increase was needed for the induction of platelet aggregation. The inhibition of aggregation with alpha(IIb)beta3 antagonists had no effect on [Ca2+]i change and TXB2 production induced by TRAP. Inhibition studies using anti-GPIb antibodies suggested that GPIb may be involved in the thrombin response, but not in the TRAP. Our findings suggest that low dose thrombin causes a different [Ca2+]i response and TXA2 producing signal from TRAP. Endogenous ADP release and fibrinogen binding to alpha(IIb)beta3 are responsible for the synthesis of TXA2 which results in the induction of the second peak of [Ca2+]i in low thrombin- but not TRAP-stimulated platelets.

Diversity revealed by a novel family of cadherins expressed in neurons at a synaptic complex

In mammals, neurons are highly differentiated and play distinctive functions even in the same brain region. We found a novel cadherin-related neuronal receptor (Cnr) gene family by studying Fyn-binding activity in mouse brain. CNR1 protein is located in the synaptic junction and forms a complex with Fyn. Sequence analysis of eight Cnr products of approximately 20 genes indicates that these comprise a novel cadherin family of the cadherin superfamily. The expression patterns of each member of this novel family were grossly similar to each other but restricted to subpopulations of neurons of the same type. The diversity of the Cnr family genes suggests that there are molecular mechanisms that govern highly differentiated neural networks in the mammalian CNS.

Propentofylline improves learning and memory deficits in rats induced by beta-amyloid protein-(1-40)

We have reported that continuous infusion of beta-amyloid protein-(1-40) into the cerebral ventricle produces learning and memory deficits in rats. Propentofylline has potent stimulatory effects on nerve growth factor (NGF) synthesis/secretion in mouse astrocytes in vitro and increases cerebral NGF content in aged rats. In the present study, we examined the effects of propentofylline on learning and memory deficits in beta-amyloid protein-infused rats. The rats were given propentofylline orally once a day throughout the period of behavioral examination. In the beta-amyloid protein-infused rats, spontaneous alternation behavior in a Y-maze, and performance in water maze and passive avoidance tasks were significantly impaired compared to sham-operated rats. Propentofylline prevented these behavioral deficits, but did not change the reduction of the activity of choline acetyltransferase in the hippocampus in the beta-amyloid protein-infused rats. These results suggest that propentofylline is useful for the treatment of patients with Alzheimer's disease.

Localization of 5-HT2A receptor in rat cerebral cortex and olfactory system revealed by immunohistochemistry using two antibodies raised in rabbit and chicken

Serotonin 2A receptor (5-HT2A receptor) is widely distributed in the central nervous system, and has been suggested to be involved in a variety of behavioral conditions and neuropsychiatric disorders. Two polyclonal antibodies were raised against the N-terminus peptide of rat 5-HT2A receptor in chickens (5-HT2A-N) and a glutathione S-transferase fusion protein that contained the C-terminus of the mouse 5-HT2A receptor in rabbits (5-HT2A-C). Affinity-purified 5-HT2A-N and -C antibodies reacted strongly with a single band of 77-78 kDa in postsynaptic density proteins prepared from the rat cortex. The distribution pattern of immunoreactive structures in the rat brain was virtually the same for the two antibodies. The highest levels of immunoreactivity were observed in the olfactory bulb, neocortex, claustrum, piriform cortex, mamillary bodies, pontine nuclei, red nucleus and cranial motor nuclei. In the olfactory bulb, mitral cells were intensely labeled. In the neocortex, many immunoreactive neurons were found in layers II-VI. In layer IV of the neocortex, strong neuropil labeling was observed. In a double-labeling study using chicken 5-HT2A-N and rabbit anti-glial fibrillary acidic protein (GFAP) antibody, a considerable number of GFAP positive cells also showed 5-HT2A immunoreactivity. By using an immunoelectron microscopic technique, 5-HT2A receptor immunoreaction was shown to be localized just beneath the postsynaptic membrane thickening of asymmetric synapses.

No changes in cerebrospinal fluid levels of nitrite, nitrate and cyclic GMP with aging. Short communication

Nitric oxide (NO) is a free radical gas that plays a role in various signal transduction processes. NO has been proposed to have a function in the mechanism of synaptic plasticity, including long-term potentiation and memory formation in vivo. Because a failure in synaptic plasticity is considered to be involved in aging-associated brain dysfunction, NO production in the brain may be altered by aging. In the present study, we measured the levels of NO metabolites, nitrite and nitrate, and cyclic GMP in the cerebrospinal fluid (CSF) of human subjects without neurological or psychiatric disorders. There were no age-related changes in the CSF levels of either nitrite, nitrate or cyclic GMP. These results suggest that NO production in the brain may be maintained during the aging process.

Comparison of the antithrombotic effects of FK633, GPIIb/IIIa antagonist, and aspirin in a guinea pig thrombosis model

Antiplatelet and antithrombotic effects of FK633 (a GPIIb/IIIa antagonist) and aspirin were compared. FK633 at 0.32 mg/kg i.v. or aspirin at 10 mg/ kg i.v. inhibited ex vivo collagen-induced aggregation by >50% for 1 hour in guinea pigs. However, aspirin was very weak in inhibiting ADP-induced aggregation. In vivo antithrombotic effects of FK633 and aspirin were compared using a FeCl3-induced carotid artery thrombosis model in guinea pigs. Pretreatment with 0.32 mg/kg i.v. of FK633 significantly prevented occlusive thrombus formation, but aspirin at 10 mg/kg i.v. did not. In thrombolysis experiments, adjunctive use of FK633 (0.32 mg/kg i.v.) with rt-PA (0.3 mg/kg bolus+1.0 mg/kg/hr) achieved reperfusion in five of five animals without reocclusion. Aspirin (10O mg/kg i.v.) with rt-PA also achieved reperfusion in three of five animals with high incidence of reocclusion. These results suggest that FK633 may be a more effective antithrombotic agent than aspirin due to its agonist-independent antiplatelet effects.

Changes in extracellular nitrite and nitrate levels after inhibition of glial metabolism with fluorocitrate

The role of glial cells in nitric oxide production in the cerebellum of conscious rats was investigated with a glial selective metabolic inhibitor, fluorocitrate. The levels of nitric oxide metabolites (nitrite plus nitrate) in the dialysate following in vivo microdialysis progressively increased to more than 2-fold the basal levels during a 2-h infusion of fluorocitrate (1 mM), and the increase persisted for more than 2 h after the treatment. Pretreatment with N(G)-nitro-L-arginine methyl ester attenuated the fluorocitrate-induced increase in nitric oxide metabolite levels. None of the glutamate receptor antagonists, including D(-)-2-amino-5-phosphonopentanoic acid, 6,7-dinitroquinoxaline-2,3-dione, and (+/-)-alpha-methyl-4-carboxyphenylglycine, inhibited the fluorocitrate-induced increase. The L-arginine-induced increase was significantly reduced by fluorocitrate treatment, while N-methyl-D-aspartate, (+)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, and trans-(+/-)-1-amino-(1S,3R)-cyclopentane-dicarboxylic acid increased nitric oxide metabolites levels in the fluorocitrate-treated rats, as much as in control animals. These results suggest that glial cells play an important role in modulating nitric oxide production in the cerebellum by regulating L-arginine availability.

The anti-platelet and anti-thrombotic effects of FK633, a peptide-mimetic GPIIB/IIIA antagonist

The anti-platelet and anti-thrombotic properties of FK633, a peptide mimetic GPIIb/IIIa antagonist were studied. In human platelet rich plasma, FK633 inhibited ADP-, collagen-, thrombin-, and PAF-induced platelet aggregation with IC50 values of 103, 87, 98, and 239 nM, respectively. RGDS acted similarly, but it's potency was about 1,000 times weaker than FK633, FK633 inhibited 125I-fibrinogen binding to human washed platelet with an IC50 of 88 nM. FK633 did not inhibit alphavbeta3, alpha5beta1, and alphavbeta1 integrin-mediated cellular adhesion up to 1.0mM, while RGDS inhibited all these interactions. In dogs, bolus injection of FK633 at 0.1 mg/kg significantly suppressed ex vivo ADP-induced platelet aggregation (>40% inhibition) and thrombus formation at stenosed and injured coronary artery, but did not prolong template bleeding time. However, FK633 inhibited >90% ADP-induced aggregation at 0.32 mg/kg, causing significant prolongation of the bleeding time. Thus, FK633 is a specific GPIIb/IIIa antagonist with potent anti-thrombotic effect in vivo, but careful dosing study might be necessary to avoid the bleeding complications in the clinic.