Adiponectin regulates functions of gingival fibroblasts and periodontal ligament cells

BACKGROUND AND OBJECTIVE

Adiponectin is a cytokine constitutively produced by adipocytes and exhibits multiple biological functions by targeting various cell types. However, the effects of adiponectin on primary gingival fibroblasts and periodontal ligament cells are still unexplored. Therefore, we investigated the effects of adiponectin on gingival fibroblasts and periodontal ligament cells.

MATERIAL AND METHODS

The expression of adiponectin receptors (AdipoR1 and AdipoR2) on human gingival fibroblasts (HGFs), mouse gingival fibroblasts (MGFs) and human periodontal ligament (HPDL) cells was examined using RT-PCR and western blotting. HGFs and MGFs were stimulated with interleukin (IL)-1β in the presence or absence of adiponectin, and the expression of IL-6 and IL-8 at both mRNA and protein levels was measured by real-time PCR and ELISA, respectively. Furthermore, small interfering RNAs (siRNAs) in MGFs were used to knock down the expression of mouse AdipoR1 and AdipoR2. The effects of adiponectin on the expression of alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2) genes were evaluated by real-time PCR. Mineralized nodule formation of adiponectin-treated HPDL cells was revealed by Alizarin Red staining.

RESULTS

AdipoR1 and AdipoR2 were expressed constitutively in HGFs, MGFs and HPDL cells. Adiponectin decreased the expression of IL-6 and IL-8 in IL-1β-stimulated HGFs and MGFs. AdipoR1 siRNA in MGFs revealed that the effect of adiponectin on reduction of IL-6 expression was potentially mediated via AdipoR1. Adiponectin-treated HPDL cells promoted the expression of ALP and Runx2 mRNAs and up-regulated ALP activity. Furthermore, adiponectin enhanced mineralized nodule formation of HPDL cells.

CONCLUSION

Our observations demonstrate that adiponectin exerts anti-inflammatory effects on HGFs and MGFs, and promotes the activities of osteoblastogenesis of HPDL cells. We conclude that adiponectin has potent beneficial functions to maintain the homeostasis of periodontal health, improve periodontal lesions, and contribute to wound healing and tissue regeneration.

Beneficial effect of risedronate for preventing recurrent hip fracture in the elderly Japanese women

SUMMARY

A 36-month observational study compared the incidence of unaffected side hip fracture in Japanese female osteoporosis patients with a history of hip fracture between 173 patients receiving risedronate and 356 risedronate-untreated controls. New hip fractures were significantly less frequent in the risedronate group, suggesting a preventive effect in high-risk patients.

INTRODUCTION

The purpose of this study was to investigate the preventive effect of risedronate on second hip fracture immediately following a first hip fracture in Japanese female osteoporosis patients with unilateral hip fracture.

METHODS

We conducted a prospective matched cohort study in 184 patients treated with risedronate and 445 patients not receiving risedronate after discharge from hospital. Both groups were followed-up for 36 months, and the incidence of unaffected side hip fracture and the frequency of adverse events were assessed.

RESULTS

Efficacy could be investigated in 173 patients from the risedronate group and 356 patients from the control group. Hip fracture was detected in 5 and 32 patients, respectively. Kaplan-Meier estimates of the 36-month fracture incidence were 4.3% in the risedronate group and 13.1% in the control group (P = 0.010, log-rank test). The hazard ratios (95% confidence intervals) obtained by univariate and multivariate analysis were 0.310 (0.121-0.796) and 0.218 (0.074-0.639), respectively, indicating a significantly lower incidence of unaffected side hip fracture in the risedronate group. Adverse events occurred in 38 patients (48 events) from the risedronate group and 94 patients (108 events) from the control group, with serious adverse events in 21 patients (26 events) and 78 patients (88 events), respectively.

CONCLUSIONS

No significant differences were observed between the two groups. The incidence of unaffected side hip fracture was significantly lower in the risedronate group. Accordingly, risedronate may have a preventive effect on hip fracture in high-risk Japanese female osteoporosis patients for fracture with a history of unilateral hip fracture.

De novo mutations of voltage-gated sodium channel alphaII gene SCN2A in intractable epilepsies

BACKGROUND

Mutations of voltage-gated sodium channel alpha(II) gene, SCN2A, have been described in a wide spectrum of epilepsies. While inherited SCN2A mutations have been identified in multiple mild epilepsy cases, a de novo SCN2A-R102X mutation, which we previously reported in a patient with sporadic intractable childhood localization-related epilepsy, remains unique. To validate the involvement of de novo SCN2A mutations in the etiology of intractable epilepsies, we sought to identify additional instances.

METHODS

We performed mutational analyses on SCN2A in 116 patients with severe myoclonic epilepsy in infancy, infantile spasms, and other types of intractable childhood partial and generalized epilepsies and did whole-cell patch-clamp recordings on Na(v)1.2 channels containing identified mutations.

RESULTS

We discovered 2 additional de novo SCN2A mutations. One mutation, SCN2A-E1211K, was identified in a patient with sporadic infantile spasms. SCN2A-E1211K produced channels with altered electrophysiologic properties compatible with both augmented (an approximately 18-mV hyperpolarizing shift in the voltage dependence of activation) and reduced (an approximately 22-mV hyperpolarizing shift in the voltage dependence of steady-state inactivation and a slowed recovery from inactivation) channel activities. The other de novo mutation, SCN2A-I1473M, was identified in a patient with sporadic neonatal epileptic encephalopathy. SCN2A-I1473M caused an approximately 14-mV hyperpolarizing shift in the voltage dependence of activation.

CONCLUSIONS

The identified de novo mutations SCN2A-E1211K, -I1473M, and -R102X indicate that SCN2A is an etiologic candidate underlying a variety of intractable childhood epilepsies. The phenotypic variations among patients might be due to the different electrophysiologic properties of mutant channels.

Activation of adenosine receptor on gingival fibroblasts

CD73 (ecto-5'-nucleotidase) on human gingival fibroblasts plays a role in the regulation of intracellular cAMP levels through the generation of adenosine, which subsequently activates adenosine receptors. In this study, we examined the involvement of ecto-adenosine deaminase, which can be anchored to CD26 on human gingival fibroblasts, in metabolizing adenosine generated by CD73, and thus attenuating adenosine receptor activation. Ecto-adenosine deaminase expression on fibroblasts could be increased by pre-treatment with a lysate of Jurkat cells, a cell line rich in cytoplasmic adenosine deaminase. Interestingly, the cAMP response to adenosine generated from 5'-AMP via CD73 and the ability of 5'-AMP to induce hyaluronan synthase 1 mRNA were significantly decreased by the pre-treatment of fibroblasts with Jurkat cell lysate. This inhibitory effect was reversed by the specific adenosine deaminase inhibitor. These results suggest that ecto-adenosine deaminase metabolizes CD73-generated adenosine and regulates adenosine receptor activation.

A voltage-gated potassium channel, Kv3.1b, is expressed by a subpopulation of large pyramidal neurons in layer 5 of the macaque monkey cortex

In the cerebral cortex, the voltage-gated potassium channel, Kv3.1b, a splicing variant of Kv3.1, has been associated with fast-firing interneurons. Here, we report strong expression of Kv3.1b-protein and mRNA in both Betz and Meynert pyramidal cells of the monkey, as shown by immunohistochemistry and in situ hybridization. Strong expression also occurs in large pyramidal neurons in layer 5 of several cortical areas. In addition, most of these Betz and layer 5 pyramids, and about 10% of the labeled Meynert cells weakly co-expressed the calcium binding protein parvalbumin. Electron microscopy shows that the expression of Kv3.1b is localized to the somal and proximal dendritic cytoplasmic membrane, as expected for a channel protein. These results suggest that some large pyramidal neurons may constitute a functional subpopulation, with a distinctive distribution of voltage-gated potassium channels capable of influencing their repetitive firing properties.

Mitochondrial protease Omi/HtrA2 enhances caspase activation through multiple pathways

Omi/HtrA2 is a mitochondrial serine protease that is released into the cytosol during apoptosis and promotes cytochrome c (Cyt c)dependent caspase activation by neutralizing inhibitor of apoptosis proteins (IAPs) via its IAP-binding motif. The protease activity of Omi/HtrA2 also contributes to the progression of both apoptosis and caspase-independent cell death. In this study, we found that wild-type Omi/HtrA2 is more effective at caspase activation than a catalytically inactive mutant of Omi/HtrA2 in response to apoptotic stimuli, such as UV irradiation or tumor necrosis factor. Although similar levels of Omi/HtrA2 expression, XIAP-binding activity, and Omi/HtrA2 mitochondrial release were observed among cells transfected with catalytically inactive and wild-type Omi/HtrA2 protein, XIAP protein expression after UV irradiation was significantly reduced in cells transfected with wild-type Omi/HtrA2. Recombinant Omi/HtrA2 was observed to catalytically cleave IAPs and to inactivate XIAP in vitro, suggesting that the protease activity of Omi/HtrA2 might be responsible for its IAP-inhibiting activity. Extramitochondrial expression of Omi/HtrA2 indirectly induced permeabilization of the outer mitochondrial membrane and subsequent Cyt c-dependent caspase activation in HeLa cells. These results indicate that protease activity of Omi/HtrA2 promotes caspase activation through multiple pathways.

A new cytochemical method for ultrastructural localization of Co2+ in rat hippocampal CA1 pyramidal neurons in vitro

This paper describes new cytochemical method for the ultrastructural localization of Co(2+) following blockade of synaptic transmission. In the CA1 region of rat hippocampal slices, electrical stimulation of the Schaffer collaterals elicited field excitatory postsynaptic potentials (fEPSPs). The fEPSPs were completely blocked within 2 min after the addition of Co(2+) (2 mM). The slice was then fixed and precipitated Co(2+) was examined by means of a solution containing 2.5% glutaraldehyde and 10 mM K(3)[Fe(3+)(CN)(6)] in 90 mM NaCl. Electron spectroscopic imaging confirmed Co in the precipitate. The precipitates were found as clusters on the membranes of the fine apical dendrites and their spine heads of CA1 pyramidal neurons. No clustered precipitate was found when slices were treated: (1) without Co(2+); (2) after recovery from the Co(2+)-induced blockade of fEPSPs; (3) without electrical stimulation of the Schaffer collaterals; and (4) with dl-2-amino-5-phosphonopentanoate and 6-cyano-7-nitroquinoxaline-2,3-dione. After administrating glutamate (5 mM) in the presence of tetrodotoxin (1 microM) and Co(2+), precipitates were found on dendritic membranes and spine heads. These results indicate that the Schaffer collaterals stimulation induces the binding of Co(2+) on CA1 pyramidal neuron membrane.

Induction of CD13 on T-lymphocytes by adhesive interaction with gingival fibroblasts

Lymphocytes in peripheral blood do not express CD13 (aminopeptidase N), a membrane alanyl metallopeptidase. However, it has been demonstrated that locally infiltrated lymphocytes in chronic inflammatory sites can be CD13-positive, and possible involvement of stromal cell adherence in the induction of CD13 has been suggested. In this study, we examined whether T-lymphocyte/gingival-fibroblast interaction can activate T-lymphocytes to express CD13. CD13 expression was induced on PMA-activated T-lymphocytes only when they adhered directly to human gingival fibroblasts (HGF) at 2 hrs after the co-culture began, while an increase in the enzyme activity of CD13 was also confirmed in activated T-lymphocytes that had been co-cultured with HGF. Furthermore, CD13-positive T-lymphocytes were detected in inflamed gingival tissues in vivo. Analysis of these results indicates that direct interaction with HGF is essential for the induction of CD13 expression on T-lymphocytes that was also observed in periodontitis lesions.

Involvement of CD73 (ecto-5'-nucleotidase) in adenosine generation by human gingival fibroblasts

Adenosine has various biological effects on human gingival fibroblasts (HGF) and epithelial cells closely associated with inflammation, such as cytokine production and cell adhesion. However, the mechanism of adenosine formation in periodontal tissues is not yet defined. In this study, we examined the involvement of CD73 (ecto-5'-nucleotidase) in adenosine generation by HGF. CD73 was detected on in vitro-maintained HGF by immunocytochemistry and flow cytometric analysis. Adenosine production was observed following the addition of 5'-AMP, the substrate of CD73-associated ecto-5'-nucleotidase. Moreover, the addition of 5'-AMP to cultured HGF resulted in the elevation of cyclic adenosine monophosphate (cAMP). The 5'-AMP-induced increase in intracellular cAMP level was inhibited markedly by xanthine amine congener, an adenosine receptor antagonist, and partially by alpha,beta-methylene adenosine 5'-diphosphate, an ecto-5'-nucleotidase inhibitor. These results suggest that CD73 on HGF is a critical enzyme responsible for the generation of adenosine, an immunomodulator that activates adenosine receptors.

Sast124, a novel splice variant of syntrophin-associated serine/threonine kinase (SAST), is specifically localized in the restricted brain regions

Syntrophin is an adaptor protein that binds signaling molecules to the dystrophin-associated protein complex, which connects extracellular matrix to intracellular cytoskeleton for construction and maintenance of the postsynaptic structures in the neuromuscular junction and the CNS. Among these signaling molecules, a family of microtubule-associated serine/threonine kinases has a unique structural feature with a serine/threonine kinase domain and a postsynaptic density protein-95/discs large/zona occludens-1 domain. In the present study, we identified syntrophin-associated serine/threonine kinase-124, a novel splice variant of the syntrophin-associated serine/threonine kinase which is a member of the microtubule-associated serine/threonine kinases family. Comparing to the original clone (syntrophin-associated serine/threonine kinase-170), syntrophin-associated serine/threonine kinase-124 is truncated just downstream of the postsynaptic density protein-95/discs large/zona occludens-1 domain. Using a monoclonal antibody specifically recognizing syntrophin-associated serine/threonine kinase-124, strong expression of the protein was observed in neurons of the subventricular zone and granule cells of the olfactory bulb, Islands of Calleja, hippocampal dentate gyrus and cerebellum. syntrophin-associated serine/threonine kinase-124 is selectively localized in the nuclei of neurons and distinct from syntrophin-associated serine/threonine kinase-170, which is interacting with syntrophin on the cell surface. Considering the tissue and subcellular distributions of syntrophin-associated serine/threonine kinase-124, it is suggested that syntrophin-associated serine/threonine kinase-124 may have functions in transcriptional regulation for the features commonly shared by these neurons. On the other hand, syntrophin-associated serine/threonine kinase-124 was also localized in glia-like cell bodies in the corpus callosum and fiber bundles in the spinal trigeminal and solitary tracts, suggesting syntrophin-associated serine/threonine kinase-124 may have other functions in these types of cells.

Activation of adenosine-receptor-enhanced iNOS mRNA expression by gingival epithelial cells

A series of reports has revealed that adenosine has a plethora of biological actions toward a large variety of cells. In this study, we investigated the influence of adenosine receptor activation on iNOS mRNA expression in human gingival epithelial cells (HGEC) and SV-40-transformed HGEC. HGEC expressed adenosine receptor subtypes A1, A2a, and A2b, but not A3 mRNA. Ligation of adenosine receptors by a receptor agonist, 2-chloroadenosine (2CADO), enhanced iNOS mRNA expression by both HGEC and transformed HGEC. In addition, the adenosine receptor agonist enhanced the production of NO(2)(-)/NO(3)(-), NO-derived stable end-products. An enhanced expression of iNOS mRNA and NO(2)(-)/NO(3)(-) was also observed when SV40-transformed HGEC were stimulated with CPA or CGS21680, A1- or A2a-selective adenosine receptor agonists, respectively. These results provide new evidence for the possible involvement of adenosine in the regulation of inflammatory responses by HGEC in periodontal tissues.

Roles of glutamate receptor delta 2 subunit (GluRdelta 2) and metabotropic glutamate receptor subtype 1 (mGluR1) in climbing fiber synapse elimination during postnatal cerebellar development

Climbing fiber (CF) synapse formation onto cerebellar Purkinje cells (PCs) is critically dependent on the synaptogenesis from parallel fibers (PFs), the other input to PCs. Previous studies revealed that deletion of the glutamate receptor delta2 subunit (GluRdelta2) gene results in persistent multiple CF innervation of PCs with impaired PF synaptogenesis, whereas mutation of the metabotropic glutamate receptor subtype 1 (mGluR1) gene causes multiple CF innervation with normal PF synaptogenesis. We demonstrate that atypical CF-mediated EPSCs (CF-EPSCs) with slow rise times and small amplitudes coexisted with typical CF-EPSCs with fast rise times and large amplitudes in PCs from GluRdelta2 mutant cerebellar slices. CF-EPSCs in mGluR1 mutant and wild-type PCs had fast rise times. Atypical slow CF responses of GluRdelta2 mutant PCs were associated with voltage-dependent Ca(2+) signals that were confined to PC distal dendrites. In the wild-type and mGluR1 mutant PCs, CF-induced Ca(2+) signals involved both proximal and distal dendrites. Morphologically, CFs of GluRdelta2 mutant mice extended to the superficial regions of the molecular layer, whereas those of wild-type and mGluR1 mutant mice did not innervate the superficial one-fifth of the molecular layer. It is therefore likely that surplus CFs of GluRdelta2 mutant mice form ectopic synapses onto distal dendrites, whereas those of wild-type and mGluR1 mutant mice innervate proximal dendrites. These findings suggest that GluRdelta2 is required for consolidating PF synapses and restricting CF synapses to the proximal dendrites, whereas the mGluR1-signaling pathway does not affect PF synaptogenesis but is involved in eliminating surplus CF synapses at the proximal dendrites.

Adenosine regulates the IL-1 beta-induced cellular functions of human gingival fibroblasts

In this study we examined the influence of adenosine on the cellular functions of human gingival fibroblasts (HGF), such as the production of inflammatory cytokines and extracellular matrices (ECM), and the expression and function of adhesion molecules. Concerning the expression of adenosine receptors, RT-PCR analysis revealed that HGF expressed adenosine receptor A1, A2a and A2b, but not A3 mRNA. Ligation of adenosine receptors by adenosine or its related analogue, 2-chloroadenosine (2-CADO), N(6)-cyclopentyladenosine (CPA) or CGS21680 synergistically increased IL-1beta-induced IL-6 and IL-8 production. In terms of ECM expression, adenosine and the adenosine receptor agonists, 2-CADO and CPA, enhanced constitutive and IL-1beta-induced expression of hyaluronate synthase mRNA, but not the mRNA levels of other ECM, such as collagen type I, III and fibronectin. Moreover, the adherence of IL-1beta-stimulated HGF to activated lymphocytes was also inhibited by adenosine, which is in part explained by the fact that adenosine down-regulated the IL-1beta-induced expression of ICAM-1 on HGF. These results provide new evidence for the possible involvement of adenosine in the regulation of inflammatory responses in periodontal tissues.

Formation of filamentous tau aggregations in transgenic mice expressing V337M human tau

Formation of neurofibrillary tangles (NFTs) is the most common feature in several neurodegenerative diseases, including Alzheimer's disease (AD). Here we report the formation of filamentous tau aggregations having a beta-sheet structure in transgenic mice expressing mutant human tau. These mice contain a tau gene with a mutation of the frontotemporal dementia parkinsonism (FTDP-17) type, in which valine is substituted with methionine residue 337. The aggregation of tau in these transgenic mice satisfies all histological criteria used to identify NFTs common to human neurodegenerative diseases. These mice, therefore, provide a preclinical model for the testing of therapeutic drugs for the treatment of neurodegenerative disorders that exhibit NFTs.

Molecular genetic analysis of revertants from a poliovirus mutant that is specifically adapted to the mouse spinal cord

SA virus, a mutant of the Mahoney strain of type 1 poliovirus (PV1/Mahoney), replicates specifically in the spinal cords of mice and causes paralysis, although the PV1/Mahoney strain does not show any mouse neurovirulence (Q. Jia, S. Ohka, K. Iwasaki, K. Tohyama, and A. Nomoto, J. Virol. 73:6041-6047, 1999). The key mutation site for the mouse neurovirulence of SA was mapped to nucleotide (nt) 928 of the genome (A to G), resulting in the amino acid substitution of Met for Ile at residue 62 within the capsid protein VP4 (VP4062). A small-plaque phenotype of SA appears to be indicative of its mouse-neurovirulent phenotype. To identify additional amino acid residues involved in the host range determination of PV, a total of 14 large-plaque (LP) variants were isolated from a single point mutant, Mah/I4062M, that showed the SA phenotype. All the LP variants no longer showed any mouse neurovirulence when delivered via an intraspinal inoculation route. Of these, 11 isolates had a back mutation at nt 928 (G to A) that restored the nucleotide of the PV1/Mahoney type. The reversions of the remaining three isolates (LP8, LP9, and LP14) were mediated by a second site mutation. Molecular genetic analysis involving recombinants between Mah/I4062M and the LP variants revealed that the mere substitution of an amino acid residue at position 107 in VP1 (Val to Leu) (LP9), position 33 in VP2 (Val to Ile) (LP14), or position 231 in VP3 (Ile to Thr) (LP8) was sufficient to restore the PV1/Mahoney phenotype. These amino acid residues are located either on the surface or inside of the virus particle. Our results indicate that the mouse neurovirulence of PV is determined by the virion surface structure, which is formed by all four capsid proteins.

Intra- and intermolecular beta-pleated sheet formation in glutamine-repeat inserted myoglobin as a model for polyglutamine diseases

An aberrant structure of the expanded polyglutamine might be involved in the formation of aggregates in CAG repeat diseases. To elucidate structural properties of the expanded polyglutamine, we prepared sperm whale myoglobin (Mb) mutants, in which 12, 28, 35, and 50 repeats of glutamine were inserted at the corner between the C and D helices (Gln(12), Gln(28), Gln(35), and Gln(50), respectively). Circular dichroism and IR spectroscopies showed that the expanded polyglutamine, which was recognized by the monoclonal antibody 1C2 in Gln(28), Gln(35), and Gln(50) Mb forms an antiparallel beta-pleated sheet structure. Gln(50) Mb aggregates were found to comprise an intermolecular antiparallel beta-pleated sheet. Fluorescence together with (1)H NMR spectra revealed partial unfolding of the protein surface in Gln(35) and Gln(50) Mb, although the structural changes in the protein core were rather small. The present results indicate that the fluctuating beta-pleated sheet of the expanded polyglutamine exposed on the protein surface facilitates the formation of aggregates through intermolecular interactions. The present study has first established and characterized structural properties of a molecular model for polyglutamine diseases in which various lengths of polyglutamine including a pathologically expanded glutamine repeat were inserted into a structurally known protein.

Dscam is associated with axonal and dendritic features of neuronal cells

Dscam, a novel cell-adhesion molecule belonging to the Ig-superfamily mediates homophilic intercellular adhesion and is expressed abundantly in the nervous system during development. To gain better understanding on the role of Dscam in neuronal differentiation, we raised an antibody and characterized its protein product. Anti-Dscam antibody detected an approximately 200-kDa protein band in human and mouse brain lysates. Immunohistochemical studies showed that during embryonic development of mice, mouse Dscam is expressed throughout the neuronal tissues and also in nonneuronal tissues such as lung, liver, and limb buds. In adult brain Dscam expression is predominant in the cerebellum, hippocampus, and olfactory bulb. Immunofluorescence double labeling of hippocampal and cerebellar primary cultures revealed that Dscam is associated with axonal and dendritic processes. In view of its cellular localization and spatiotemporal expression pattern, we suggest that Dscam is involved in cell-cell interactions during axonal-dendritic development, and maintenance of functional neuronal networks.

Early and progressive accumulation of reactive microglia in the Huntington disease brain

Microglia may contribute to cell death in neurodegenerative diseases. We studied the activation of microglia in affected regions of Huntington disease (HD) brain by localizing thymosin beta-4 (Tbeta4), which is increased in reactive microglia. Activated microglia appeared in the neostriatum, cortex, and globus pallidus and the adjoining white matter of the HD brain, but not in control brain. In the striatum and cortex, reactive microglia occurred in all grades of pathology, accumulated with increasing grade, and grew in density in relation to degree of neuronal loss. The predominant morphology of activated microglia differed in the striatum and cortex. Processes of reactive microglia were conspicuous in low-grade HD, suggesting an early microglia response to changes in neuropil and axons and in the grade 2 and grade 3 cortex, were aligned with the apical dendrites of pyramidal neurons. Some reactive microglia contacted pyramidal neurons with huntingtin-positive nuclear inclusions. The early and proximate association of activated microglia with degenerating neurons in the HD brain implicates a role for activated microglia in HD pathogenesis.

Differential subcellular localization of zinc in the rat retina

In the retina, zinc is believed to be a modulator of synaptic transmission and a constituent of metalloenzymes. To determine whether the intracellular localization of zinc correlates with function, we examined the localization of endogenous zinc in the rat retina using the silver amplification method. By light microscopy, reaction products were detected in the pigment epithelial cells (PE), the inner segment of photoreceptors (IS), the outer nuclear layer (ONL) and the inner nuclear layer (INL), the outer plexiform layer (OPL) and the inner plexiform layer (IPL), and the ganglion cell layer (GC). The heaviest accumulation of precipitate was observed in PE and IS, whereas only a little precipitate was found in GC. When the intracellular zinc was chelated with diethyldithiocarbamate, a small amount of precipitate was observed only in ONL. By electron microscopy, zinc was associated with three compartments. In OPL and IPL, zinc was associated with neural processes, while in PE, IS, INL, and GC it was associated with the Golgi apparatus. In ONL, zinc was associated with the nucleus. Zinc in the neural processes is believed to act as a modulator of synaptic transmission, and zinc associated with the Golgi apparatus is assumed to catalyze metalloenzyme reactions.

The occ1 gene is preferentially expressed in the primary visual cortex in an activity-dependent manner: a pattern of gene expression related to the cytoarchitectonic area in adult macaque neocortex

Marker molecules to visualize specific subsets of neurons are useful for studying the functional organization of the neocortex. One approach to identify such molecular markers is to examine the differences in molecular properties among morphologically and physiologically distinct neuronal cell types. We used differential display to compare mRNA expression in the anatomically and functionally distinct areas of the adult macaque neocortex. We found that a gene, designated occ1, was preferentially transcribed in the posterior region of the neocortex, especially in area 17. Complete sequence analysis revealed that occ1 encodes a macaque homolog of a secretable protein, TSC-36/follistatin-related protein (FRP). In situ hybridization histochemistry confirmed the characteristic neocortical expression pattern of occ1 and showed that occ1 transcription is high in layers II, III, IVA and IVC of area 17. In addition, occ1 transcription was observed selectively in cells of the magnocellular layers in the lateral geniculate nucleus (LGN). Dual labeling immunohistochemistry showed that the occ1-positive neurons in area 17 include both gamma-aminobutyric acid (GABA)-positive aspiny inhibitory cells and the alpha-subunit of type II calcium/calmodulin-dependent protein kinase (CaMKII alpha)-positive spiny excitatory cells. With brief periods of monocular deprivation, the occ1 mRNA level decreased markedly in deprived ocular dominance columns of area 17. From this we conclude that the expression of occ1 mRNA is present in a subset of neurons that are preferentially localized in particular laminae of area 17 and consist of various morphological and physiological neuronal types, and, furthermore, occ1 transcription is subject to visually driven activity-dependent regulation.

Laforin, defective in the progressive myoclonus epilepsy of Lafora type, is a dual-specificity phosphatase associated with polyribosomes

The progressive myoclonus epilepsy of Lafora type is an autosomal recessive disorder caused by mutations in the EPM2A gene. EPM2A is predicted to encode a putative tyrosine phosphatase protein, named laforin, whose full sequence has not yet been reported. In order to understand the function of the EPM2A gene, we isolated a full-length cDNA, raised an antibody and characterized its protein product. The full-length clone predicts a 38 kDa laforin that was very close to the size detected in transfected cells. Recombinant laforin was able to hydrolyze phosphotyrosine as well as phosphoserine/threonine substrates, demonstrating that laforin is an active dual-specificity phosphatase. Biochemical, immunofluorescence and electron microscopic studies on the full-length laforin expressed in HeLa cells revealed that laforin is a cytoplasmic protein associated with polyribosomes, possibly through a conformation-dependent protein-protein interaction. We analyzed the intracellular targeting of two laforin mutants with missense mutations. Expression of both mutants resulted in ubiquitin-positive perinuclear aggregates suggesting that they were misfolded proteins targeted for degradation. Our results suggest that laforin is involved in translational regulation and that protein misfolding may be one of the molecular bases of the Lafora disease phenotype caused by missense mutations in the EPM2A gene.

Connections between anterior inferotemporal cortex and superior temporal sulcus regions in the macaque monkey

We examined the connections between the anterior inferotemporal cortex and the superior temporal sulcus (STS) in the macaque monkey by injecting Phaseolus vulgaris leucoagglutinin (PHA-L) or wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the dorsoanterior and ventroanterior subdivisions of TE (TEad and TEav, respectively) and observing the labeled terminals and cell bodies in STS. We found a clear dichotomy in the connections of the rostral part of STS: the injections into TEad resulted in a dense distribution of labeled terminals and cell bodies in the upper bank of rostral STS, whereas labeling was confined to the lower bank and fundus of rostral STS after injections into TEav. The distribution of labeling in the rostral STS was discontinuous from the distribution of labeling surrounding the injection sites: the lower bank of the rostral STS was spared from labeling in the TEad injection cases, and TEad had only sparse distribution in the TEav injection cases. These results revise the classical view that the lower bank of rostral STS is connected with TE, whereas the upper bank of rostral STS is connected with the parietal, prefrontal, and superior temporal regions (Seltzer and Pandya, 1978, 1991, 1994). The upper bank of the rostral STS is called the superior temporal polysensory area (STP), because it was previously found that neurons there respond to auditory, somatosensory, and visual stimuli. The present results thus suggest that the polymodal representation in STP interacts more with information processing in TEad than TEav. It is also suggested that the information processing in the ventral bank of the rostral STS is distinct from that in TEad, and the former more directly interacts with TEav than TEad.

Adenosine regulates the production of interleukin-6 by human gingival fibroblasts via cyclic AMP/protein kinase A pathway

Adenosine has been reported to alter a variety functions of the cells that participate in inflammatory responses. However, the effect(s) of adenosine on human gingival fibroblasts (HGF), one of the immunomodulator cells in inflamed periodontal lesions, remains to be established. In this study, we examined the influence of adenosine on the production of interleukin (IL)-6 by HGF. Ligation of adenosine receptors with adenosine or its related analogue, 2-chloroadenosine (2-CADO), increased IL-6 production by HGF without any other stimuli. In addition, adenosine and 2-CADO enhanced the cyclic AMP (cAMP) level in HGF as did prostaglandin E1 (PGE1) and forskolin. Interestingly, these cAMP-arising reagents and the permeable cAMP analogue, dibutyryl cAMP (dbtcAMP), also increased IL-6 production by HGF. These results suggest that cAMP is involved in adenosine-induced IL-6 production by HGF. Adenosine-induced IL-6 production was suppressed by protein kinase A (PKA) inhibitor, H89, indicating that cAMP/PKA pathway is involved in the induction. Moreover, the experiments using antagonists specific for adenosine receptor subtypes revealed that the adenosine-induced IL-6 production by HGF was, at least in part, mediated by the adenosine A2b receptor. These results provide new evidence for the possible effects of adenosine or its related analogue as an immunomodulator in inflammatory periodontal lesions.

Roles of neuregulin in synaptogenesis between mossy fibers and cerebellar granule cells

Neuregulins (NRGs), a large group of structurally related signaling proteins, are likely to have important roles in the development, maintenance and repair of the nervous system and other selected tissues. We have demonstrated, by using the major form of NRG cloned from the mouse cerebellum that both the soluble form and the membrane anchored form of NRG may serve different functions in synaptogenesis. The soluble form of NRG was produced by proteolytic cleavage of the membrane anchored form of NRG. The proteolytic cleavage was promoted by protein kinase activation. The cleaved form of NRG trans-synaptically regulated the expression of the NMDA (N-methyl-D-aspartate) receptor subunit NR2C as neurally-derived factors, whereas the membrane anchored form of NRG showed a homophilic binding activity between NRGbeta1s. In adult mice the membrane anchored form of NRG was concentrated in neuro-terminals of both granule cells and pontocerebellar mossy fibers. The fact that NRG can be functionally viewed as cell recognition molecules as well as neurotrophic agents suggests new possibilities for the important class of molecules.

Differential expression of gamma-aminobutyric acid type B receptor-1a and -1b mRNA variants in GABA and non-GABAergic neurons of the rat brain

To understand the heterogeneity of gamma-aminobutyric acid type B receptor (GABABR)-mediated events, we investigated expression of GABABR1a and 1b mRNA variants in GABA and non-GABAergic neurons of the rat central nervous system (CNS), by using nonradioactive in situ hybridization histochemistry and, in combination with GABA immunocytochemistry, double labeling. In situ hybridization with a pan probe, which recognizes a common sequence of both GABABR1a and GABABR1b mRNA variants, demonstrated widespread expression of GABABR1 mRNA at various levels in the CNS. Both GABABR1a and GABABR1b were expressed in the neocortex, hippocampus, dorsal thalamus, habenula, and septum, but only GABABR1a was detected in cerebellar granule cells, in caudate putamen, and most hindbrain structures. A majority of GABA neurons in cerebral cortex showed hybridization signals for both GABABR1a and GABABR1b, whereas those in most subcortical structures expressed either or neither of the two. GABA neurons in thalamic reticular nucleus and caudate putamen hybridized primarily for GABABR1a. Purkinje cells in the cerebellar cortex expressed predominantly GABABR1b. GABA neurons in dorsal lateral geniculate nucleus did not display significant levels of either GABABR1a or GABABR1b mRNAs. These data suggested widespread availability of GABABR-mediated inhibition in the CNS. The differential but overlapping expression of GABABR1 mRNA variants in different neurons and brain structures may contribute to the heterogeneity of GABABR-mediated inhibition. Some GABA neurons possessed, but others might lack the molecular machinery for GABABR-mediated disinhibition, autoinhibition, or both.

Ultrastructural evidence for dendritic release of acetylcholinesterase in the rat substantia nigra

Morphological evidence for dendritic secretion of acetylcholinesterase (AChE) in rat substantia nigra--a physiologically known phenomenon--was searched by means of a modified cytochemical method devised for fine localization of AChE activity at the electron microscopic level. DAB precipitate was observed in cluster of small vesicles in contact with the plasma membrane and in the extracellular space in the vicinity of the vesicles. Single coated or uncoated large vesicles filled with stained material were found in the cytoplasm of the dendrites at distance from or in contact with the plasma membrane. Immunoperoxidase staining with specific anti-serum against rat AChE gave similar localization of AChE. These results suggest that AChE is released from the dendrites of the nigral neurons by a process of vesicular exocytosis and captured by endocytosis. The relation of this process to a putative release from the smooth endoplasmic reticulum remains to be elucidated.

Neurochemical gradients along monkey sensory cortical pathways: calbindin-immunoreactive pyramidal neurons in layers II and III

We examined the distribution of neurons containing immunoreactivity for three calcium-binding proteins, calbindin, parvalbumin and calretinin, as well as nonphosphorylated neurofilament protein, in cortical areas along the ventral and dorsal cortical visual pathways, and in ventrally-directed somatosensory and auditory cortical pathways. Calbindin-immunoreactive pyramidal neurons showed the most prominent regional differences. They were largely restricted to layers II and III and their number monotonically increased from the primary sensory areas to the anteroventral areas along the ventral visual pathway and along the ventrally-directed somatosensory and auditory pathways. The number of calbindin-immunoreactive pyramidal neurons in layers II and III also increased along the dorsal visual pathway, but the number in the last recognized stage of the dorsal visual pathway (area 7a) was significantly smaller than that at the corresponding stage in the ventral visual pathway (TE). The number of calbindin-immunoreactive pyramidal neurons was highest in layers II and III of areas 35/36, TG, and TF/TH, which represent terminal cortical regions of the pathways. These results show neurochemical differences between cortical areas located at early and late stages along serial corticocortical pathways, as well as confirming differences between pyramidal neurons in the supragranular and infragranular layers.

Connections of the dorsal zone of cat auditory cortex

The present study examined the anatomic connections of the dorsal zone of cat auditory cortex (DZ). The DZ was discriminated physiologically from the primary auditory field (AI) on the basis of neuronal responses with long latency and broad or multipeaked tuning curves. Wheat germ agglutinin-horseradish peroxidase was then injected either by pressure or iontophoretically. The thalamocortical and corticothalamic connections of the DZ were visualized by the presence of retrogradely labeled neurons and anterogradely labeled terminal fields in the thalamus; ipsilateral corticocortical projections from other cortical fields were visualized by the presence of retrogradely labeled cells. Injections of tracer into the DZ retrogradely labeled cells mainly in the lateral division of posterior complex (Po) and in the dorsal division (MGd) of the medial geniculate body (MGB); fewer labeled cells were found in the ventral (MGv) and medial (MGm) divisions of the MGB and in the suprageniculate nucleus. The DZ projection to Po, MGv, and MGd was heavy and was more diffuse than the reciprocal thalamocortical projection; the projection to MGm was light. The corticothalamic terminations and thalamocortical cells projecting to the same part of the DZ were not superimposed rigidly. The DZ received cortical projections from AI and from the second, anterior, and posterior auditory fields, and there were strong intra-DZ connections. Together with the physiological findings, the present results suggest that the DZ is a potentially separate auditory field from AI and is likely to be involved in both temporal and spectral integration of acoustic information.

Involvement of dendritic adhesion molecule telencephalin in hippocampal long-term potentiation

Telencephalin (TLCN) is a cell adhesion molecule belonging to the immunoglobulin superfamily whose expression is restricted to neurons within the most highly developed brain segment, telencephalon. Immunoelectronmicroscopic study revealed that in the hippocampal CA1 region, TLCN was localized at the surface membrane of postsynaptic spines of pyramidal cell dendrites but not at that of axonal terminals. Blocking of TLCN function using anti-TLCN antibody or recombinant soluble TLCN protein caused a striking suppression of the long-term potentiation (LTP) at the Schaffer collateral-CA1 synapses. The suppression was observed even when the blocking was initiated immediately after the tetanic stimuli. These observations suggest a role for TLCN-mediated cell-cell interactions as a key step in the development of LTP.

Cell- and lamina-specific expression and activity-dependent regulation of type II calcium/calmodulin-dependent protein kinase isoforms in monkey visual cortex

In situ hybridization histochemistry and immunocytochemistry were used to study localization and activity-dependent regulation of alpha, beta, gamma, and delta isoforms of type II calcium/calmodulin-dependent protein kinase (CaMKII) and their mRNAs in areas 17 and 18 of normal and monocularly deprived adult macaques. CaMKII-alpha is expressed overall at levels three to four times higher than that of CaMKII-beta and at least 15 times higher than that of CaMKII-gamma and -delta. All isoforms are expressed primarily in pyramidal cells of both areas, especially those of layers II-III, IVA (in area 17), and VI, but are also expressed in nonpyramidal, non-GABAergic cells of layer IV of both areas and in interstitial neurons of the white matter. CaMKII-alpha and -beta are colocalized, suggesting the formation of heteromers. There was no evidence of expression in neuroglial cells. Each isoform has a unique pattern of laminar and sublaminar distribution, but cortical layers or sublayers enriched for one isoform do not correlate with layers receiving inputs only from isoform-specific layers of the lateral geniculate nucleus. CaMKII-alpha and -beta mRNA and protein levels in layer IVC of area 17 are subject to activity-dependent regulation, with brief periods of monocular deprivation caused by intraocular injections of tetrodotoxin leading to a 30% increase in CaMKII-alpha mRNA and a comparable decrease in CaMKII-beta mRNA in deprived ocular dominance columns, especially of layer IVCbeta. Expression in other layers and expression of CaMKII-gamma and delta were unaffected. Changes occurring in layer IVC may influence the formation of heteromers and protect supragranular layers from CaMKII-dependent plasticity in the adult.

Cell-specific expression of type II calcium/calmodulin-dependent protein kinase isoforms and glutamate receptors in normal and visually deprived lateral geniculate nucleus of monkeys

In situ hybridization histochemistry and immunocytochemistry were used to map distributions of cells expressing mRNAs encoding alpha, beta, gamma, and delta isoforms of type II calcium/calmodulin-dependent protein kinase (CaMKII), alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate (AMPA)/ kainate receptor subunits, (GluR1-7), and N-methyl-D-aspartate (NMDA) receptor subunits, NR1 and NR2A-D, or stained by subunit-specific immunocytochemistry in the dorsal lateral geniculate nuclei of macaque monkeys. Relationships of specific isoforms with particular glutamate receptor types may be important elements in neural plasticity. CaMKII-alpha is expressed only by neurons in the S laminae and interlaminar plexuses of the dorsal lateral geniculate nucleus, but may form part of a more widely distributed matrix of similar cells extending from the geniculate into adjacent nuclei. CaMKII-beta, -gamma, and -delta isoforms are expressed by all neurons in principal and S laminae and interlaminar plexuses. In principal laminae, they are down-regulated by monocular deprivation lasting 8-21 days. All glutamate receptor subunits are expressed by neurons in principal and S laminae and interlaminar plexuses. The AMPA/kainate subunits, GluR1, 2, 5, and 7, are expressed at low levels, although GluR1 immunostaining appears selectively to stain interneurons. GluR3 is expressed at weak, GluR 6 at moderate and GluR 4 at high levels. NMDA subunits, NR1 and NR2A, B, and D, are expressed at moderate to low levels. GluR4, GluR6 and NMDA subunits are down-regulated by visual deprivation. CaMKII-alpha expression is unique in comparison with other CaMKII isoforms which may, therefore, have more generalized roles in cell function. The results demonstrate that all of the isoforms are associated with NMDA receptors and with AMPA receptors enriched with GluR4 subunits, which implies high calcium permeability and rapid gating.

Tonotopic organization of auditory cortical fields delineated by parvalbumin immunoreactivity in macaque monkeys

Tonotopic maps, obtained from single and multi-unit recordings in the primary and surrounding areas of the auditory cortex, were related to chemoarchitecture of the supratemporal plane, as delineated by immunoreactivity for parvalbumin. Neurons in the central core were sharply tuned and formed two complete tonotopic representations corresponding to the primary auditory area (AI) and the rostral (R) area. High frequencies were represented posteriorly in AI and anteriorly in R, the representation reversing in the anterior part of the core. Neurons in regions of less dense immunostaining previously described as lateral (L) and posteromedial (P-m) fields, showed broader frequency tuning. Two tonotopic representations were found in L: in an anterolateral (AL) field, corresponding to a field previously reported by others, high frequencies were represented anteriorly and low frequencies posteriorly; in a posterolateral field (PL) the trend reversed. There was a further reversal on entering P-m from the high frequency representation in PL and progressively lower frequencies tended to be represented more medially in P-m, but P-m may contain two representations reported by others. Neurons in the previously described anteromedial (A-m) and medial (M) fields of weaker immunostaining, were even more broadly tuned. A tonotopic progression from low frequency representation posteriorly to high frequency representation anteriorly was observed in the medial field. Frequency representation in A-m remains uncertain. No tonotopic representation could be demonstrated with the stimuli used in the zones of very weak parvalbumin immunostaining outside AL, PL, P-m, A-m, and M. The properties of neurons in the core and surrounding zones are likely to reflect inputs from the ventral and dorsal medial geniculate nuclei, respectively. The fields outside the core seem to be the starting points for separate streams of auditory corticocortical connections passing into association cortex.

Temporal integration and duration tuning in the dorsal zone of cat auditory cortex

The present study examined auditory cortical neurons, the responses of which depended on the duration of noise bursts. We recorded from 150 neurons with response latencies exceeding 30 msec and from 28 neurons with OFF responses to auditory stimuli in the dorsal zone of cat auditory cortex. Of 150 long-latency neurons, 132 displayed some form of duration selectivity. Seventy-eight were classified as selective for long durations. Among the long-duration-selective neurons, 30 responded only to noise burst stimuli with durations longer than a minimal threshold and were classified further as duration threshold neurons. Of 132 duration-selective neurons, 41 responded selectively to noise bursts of short duration; 13 showed maximal responses to noise bursts of a particular duration and could be regarded as duration-tuned neurons. OFF-response neurons included ones that were long-duration-selective, duration-tuned, and nonduration-selective. Duration tuning has been described previously only at the midbrain level in amphibians and bats. The present finding of sensitivity to sound duration in at least one region of cat auditory cortex indicates that this form of neural tuning may be important for hearing in all vertebrates, and for processing of sound at multiple levels in the auditory pathway. The duration tuning in the cat auditory cortex was much broader, and the best duration was distributed over a wider range than in the bat inferior colliculus. We suggest that the duration selectivity of the long-latency neurons results from integration along the time domain of a stimulus during the latent period.

Immunoregulatory roles of adhesive interactions between lymphocytes and gingival fibroblasts

Chronic adult periodontitis is usually characterized by inflammatory cell accumulation in the extravascular periodontal connective tissue. In order to reveal how the lymphocyte migration and retention in periodontal lesions is regulated, we have focused on the molecular basis for the adhesive interactions between lymphocytes and human gingival fibroblasts (HGF). In this study, we investigated the involvement of cell adhesion molecules in adhesive interactions between lymphocytes and HGF. We found that activated lymphocytes bound strongly to HGF and VLA integrins, extracellular matrix receptors, play crucial roles in the binding. Interestingly, we first revealed that CD44 molecules (hyaluronate receptor) on lymphocytes also participated in lymphocyte-HGF interactions and that hyaluronate anchored on the surface of HGF functioned as the ligand for CD44. In addition, when HGF were stimulated with inflammatory cytokines such as IL-1, TNF alpha and IFN gamma, the binding avidity between lymphocytes and HGF was significantly increased and the adhesion was mainly mediated by LFA-1/ICAM-1 pathway. We then examined the possibility whether lymphocyte-HGF interaction may cause activation of HGF. When HGF directly interacted with lymphocytes for 3 h, IL-1 beta mRNA expression was clearly increased in HGF. These findings suggested that the adhesive interactions between lymphocytes and HGF was mediated at least by VLA integrins, LFA-1/ICAM-1 and CD44/hyaluronate and that the heterotypic cell-cell interactions could mutually cause intracellular signal transduction.

Restricted occurrence of an unusual ganglioside GD1 alpha in rat brain and its possible involvement in dendritic growth of cerebellar Purkinje neurons

The spatial pattern of expression of a minor disialosyl ganglioside GD1 alpha in the rat brain was investigated immunohistochemically using a specific murine monoclonal antibody KA-17. The antibody shows noticeable immunoreactivity in the proximal dendrites and neuronal cell bodies of restricted populations of neurons including cerebral pyramidal neurons and cerebellar Purkinje neurons. Immunocytochemical analysis revealed that Purkinje neurons maintained in a dissociate culture condition also express GD1 alpha in the dendrites and cell bodies. We have examined the functional involvement of this ganglioside in the growth of brain neurons using KA-17 antibody. Addition of the antibody to cerebellar primary cultures caused perturbation of the dendritic development of Purkinje neurons in a dose-dependent manner. The length and branching of the dendrites were severely decreased by the antibody treatment. When other anti-glycoconjugate or sphingolipid monoclonal antibodies were tested, only HNK-1 monoclonal antibody that recognizes sulfoglucuronic residues in glycolipids and glycoproteins had similar but moderate inhibitory actions on the dendritic development of these neurons. In contrast to the morphological alterations observed in Purkinje cells, other cerebellar cells including granule neurons appear to be almost normal following the antibody treatment. These observations lead to the possibility that GD1 alpha ganglioside has a role in the development of Purkinje cell dendrites.

Patchy and laminar terminations of medial geniculate axons in monkey auditory cortex

The object of this study was to identify the terminal distributions of thalamocortical axons arising in chemically characterized subdivisions of the medial geniculate complex. Large injections of wheat germ agglutinin-conjugated horseradish peroxidase or small injections of Phaseolus vulgaris leucoagglutinin were made in the medial geniculate complex of Macaca fuscata. The terminal distributions of labeled axons in the cortex were correlated with auditory cortical fields demonstrable by different intensities of immunoreactivity for parvalbumin. Fibers from the ventral nucleus terminated mainly in layer IV and deep portion of layer III (IIIB), with additional terminations in layers I-IIIA and in layer VI. In layers IIIB-IV, a major terminal plexus was formed by a small number of dense patches, 300-500 microns in diameter, surrounded by smaller satellite patches. The patches conformed to a similarly lobulated pattern of parvalbumin fiber immunoreactivity. Terminations of some individually labeled thalamocortical fibers were restricted to a single patch, whereas others innervated more than one patch by collateral branches. Fibers from the dorsal nuclei ending in areas of less dense parvalbumin immunoreactivity surrounding the primary auditory cortex formed much larger terminal patches centered largely in layer IIIB. Fibers from the magnocellular nucleus had relatively few terminal branches but innervated extremely wide areas by collaterals of single axons. Two types of axons arose from the magnocellular nucleus, one terminating preferentially in middle cortical layers and the other exclusively in layer I. These may arise respectively from parvalbumin- and calbindin-immunoreactive cell populations in the magnocellular nucleus.

Subdivisions of macaque monkey auditory cortex revealed by calcium-binding protein immunoreactivity

The aim of this investigation was to characterize auditory areas of the primate cerebral cortex on the basis of chemoarchitecture. Cortical areas of the supratemporal plane were delineated in Macaca fuscata (M. fuscata) by immunocytochemical staining for parvalbumin, staining for cytochrome oxidase, examination of cyto- and myeloarchitecture, and retrograde tracing of corticocortical connections. Comparative observations were made on Macaca fascicularis (M. fascicularis). Differential staining of fiber plexuses, probably of thalamic origin, identifies a central core zone of dense immunostaining and a surrounding zone of moderate-to-dense immunostaining composed of anteromedial, lateral, and posteromedial fields. Outside the second zone, there is a third anterolateral zone of weaker immunoreactivity, and, outside that zone, there is a fourth zone in which immunoreactivity is virtually absent. Differences in parvalbumin immunostaining in the auditory fields may reflect differences in relative contributions of thalamic inputs from parvalbumin-immunoreactive cells in the medial geniculate complex. The central core zone and the surrounding three fields can be correlated with major auditory fields previously defined by multiunit mapping and thalamocortical connectivity. The core zone contains a large principal field and an anterior extension. The pattern of corticocortical connections between these and adjoining fields suggests that the anteromedial, lateral, and posteromedial fields represent first steps in three streams of connections passing outward from auditory into association cortex. M. fuscata has an unusually large auditory cortex that is more deeply placed in the lateral sulcus in comparison to that of M. fascicularis. A small annectant gyrus provides a guide to the position of the primary auditory area.

Auditory thalamocortical pathways defined in monkeys by calcium-binding protein immunoreactivity

This study investigated differentiation of Macaca fuscata auditory thalamus into chemically defined nuclei forming relays to auditory cortical areas. The thalamus was stained immunocytochemically for parvalbumin and 28 kDa calbindin in normals and in brains in which retrogradely transported tracers were injected into middle layers of auditory cortical areas or applied to the cortical surface. Parvalbumin- and calbindin-immunoreactive cells show a complementary distribution in ventral, anterodorsal, posterodorsal, and magnocellular medial geniculate nuclei. The ventral nucleus has a high density of parvalbumin cells and few calbindin cells, and the anterodorsal nucleus has a high density of parvalbumin cells and moderate numbers of calbindin cells. Both nuclei have a dense parvalbumin-immunoreactive neuropil formed by terminations of fibers ascending in the brachium of the inferior colliculus. The posterodorsal nucleus has approximately equal proportions of parvalbumin and calbindin cells; neuropil staining is weak but contains terminations of calbindin-immunoreactive fibers ascending in the midbrain tegmentum. The magnocellular nucleus contains domains of parvalbumin and calbindin cells. Parvalbumin cells in the ventral nucleus project to a central core of auditory cortex with densest parvalbumin immunoreactivity. Those in anterodorsal and posterodorsal nuclei project to surrounding auditory fields with less dense parvalbumin immunoreactivity; those in the magnocellular nucleus project widely to auditory and other fields. Injections of middle cortical layers label a large majority of parvalbumin cells in the ventral, anterodorsal, or posterodorsal nuclei and in the magnocellular nucleus. Superficial deposits label calbindin cells only, usually in more than one nucleus, implying a widespread projection system.

Transient and persistent phosphorylation of AMPA-type glutamate receptor subunits in cerebellar Purkinje cells

We generated a polyclonal antibody, 12P3, specifically recognizing rat AMPA-type glutamate receptor (GluR) subunits phosphorylated at Ser-696 of GluR2 or at the homologous sites in GluR1, GluR3, and GluR4. Using 12P3, we demonstrate that a brief exposure of a rat cerebellar slice to AMPA leads to transient phosphorylation of the GluR subunits in Purkinje cell dendrites. Persistent phosphorylation over 30 min was obtained when exposure to AMPA was preceded by a 15 min perfusion of the slice with 8-bromo-cGMP, dibutyryl-cGMP, or calyculin A but not phorbol 12,13-diacetate. These results indicate that Ser-696 of GluR2, or the corresponding sites in other AMPA receptor subunits, is a specific site at which phosphorylation takes place when AMPA-type GluRs are activated by agonists, especially under the influence of certain second messenger activities.

Neuronal expression of a minor monosialosyl ganglioside GM1b in rat brain: immunochemical characterization using a specific monoclonal antibody

Monoclonal antibodies (mAbs) against GM1b ganglioside were raised by immunizing NZB/n mice with the antigen purified from bovine brains, and the details of binding specificity of the mAbs were characterized. Anti-GM1b mAb, termed NA-6, reacted specifically with GM1b (NeuAc) and GM1b(NeuGc). NA-6 antibody did not react with other structurally related gangliosides, indicating that the antibody recognizes NeuAc or NeuGc alpha 2-3Gal beta 1-4GalNAc beta 1-4Gal structure. Using NA-6 antibody, GM1b ganglioside in developing rat brain was investigated by TLC/enzyme-immunostaining and detected first on gestational day 16. The specific content of brain GM1b increased until postnatal day 10, and then gradually decreased in later stage of development. Immunohistochemically GM1b was found in proximal dendrites and cell bodies of neurons in extensive regions of adult rat brain. The immunoreactivity tended to be confined in patch-like clusters on cell membranes, as typically found in the hippocampus and neocortex. The GM1b synthase activity, when assayed in the cerebellar microsome proteins, was significantly reduced in lurcher mutant mouse that is devoid of both cerebellar granule and Purkinje cells. These findings demonstrate that GM1b ganglioside exists in neurons and is actively synthesized during the development in rat brain.

Immunohistochemical localization of protein phosphatase isoforms in the rat cerebellum

Protein phosphatase isoforms, PP1 gamma 1, PP1 delta, PP1 alpha and PP2A (alpha and/or beta), were immunohistochemically localized in the rat cerebellum. Purkinje cell perikarya, dendrites and spines were very PP1 gamma 1 immunoreactive. PP1 delta and PP1 alpha were perinuclear in all neurons, PP1 alpha also revealed a new cell type and PP2A was homogeneous in Purkinje cell soma and large dendrites. PP1 gamma 1 seems to be dominant for dephosphorylation at the dendritic synapses of Purkinje cells.

Ganglioside GD1 alpha in cerebellar Purkinje cells. Its specific absence in mouse mutants with Purkinje cell abnormality and altered immunoreactivity in response to conjunctive stimuli causing long-term desensitization

The alpha-series ganglioside, IV3NeuAc,III6NeuAcGgOse4-Cer(GD1 alpha), was previously identified as a minor constituent in bovine brain gangliosides (Hirabayashi, Y., Hyogo, A., Nakao, T., Tsuchiya, K., Suzuki, Y., Matsumoto, M., Kon, K, and Ando, S. (1990) J. Biol. Chem. 265, 8144-8151). In the present study, we have generated a specific mouse monoclonal antibody against GD1 alpha and explored the distribution of GD1 alpha in murine central nervous system. In adult rat brain, GD1 alpha occurred as a minor constituent, and its expression was exclusively detected in the forebrain, the midbrain and the cerebellum. In the mouse cerebellum, the content of GD1 alpha was reduced significantly in the Purkinje cell-deficient mutants, lurcher (Lc/+), staggerer (sg/sg), and Purkinje cell degeneration (pcd/pcd), but were not reduced in the weaver (wv/wv) mutant, which loses mostly granule cells. The GD1 alpha synthase, assayed in cerebellar microsomes, was also reduced in Purkinje cell-deficient mutants. Immunohistochemistry showed that the staining for GD1 alpha in rat and mouse cerebella was mostly found in the proximal dendrites and cell bodies of Purkinje cells. Also, it appeared slightly in the processes of Bergmann glial cells. The immunoreactivity of GD1 alpha disappeared specifically from the Purkinje cell dendrites and the Bergmann glial processes after co-application of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and 8-bromo-guanosine 3':5'-cyclic monophosphate, which induced long-term desensitization of the AMPA-selective glutamate receptors in Purkinje cells. The present data provide suggestive evidence that GD1 alpha ganglioside is enriched in Purkinje cells and may have a role in Purkinje cell functions in the cerebellum.

Distribution of cholinergic neuron-specific gangliosides (GT1a alpha and GQ1b alpha) in the rat central nervous system

A newly developed mouse monoclonal antibody, GGR-41, was used to localize a novel species of gangliosides, GT1a alpha and GQ1b alpha, in the rat central nervous system. Intense immunoreactivity was found in the neuropil of the spinal cord dorsal horn, spinal trigeminal nucleus, solitary tract nucleus, superior colliculus, interpeduncular nucleus, hypothalamus and septal area. The results suggest that GT1a alpha and GQ1b alpha are expressed in the nerve terminals of a certain population of cholinergic fibers.

Nitric oxide synthase immunoreactivity colocalized with NADPH-diaphorase histochemistry in monkey cerebral cortex

The distributions of reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) and nitric oxide synthase (NOS) containing neurons and the extent of NADPH-d and NOS colocalization have been analyzed by histochemical and immunocytochemical techniques in the neocortex of Macaca fuscata monkeys. NADPH-d positive cells were consistently also NOS positive and presented a relatively uniform distribution from area to area, but area-specific differences were observed in the pattern of distribution of fiber plexuses.

Neurochemical gradient along the monkey occipito-temporal cortical pathway

We have examined the neuronal distribution of two calcium-binding proteins, calbindin (CB) and parvalbumin (PV), along the occipito-temporal cortical pathway, which sequentially connects visual areas V1, V2, V4, TEO, and TE, and then areas TG and 36 in monkeys. Immunohistochemical staining showed that CB-containing pyramidal cells, which were mostly limited to layers 2 and 3, gradually increased in population from the posterior to the anterior areas. PV-containing non-pyramidal cells were sparser in areas TG and 36 than in the other areas. The posterior and anterior areas of the occipito-temporal cortical pathway are different in the chemical characteristics of their neurones.