The Preventive Effect of Melatonin on Radiation-Induced Oral Mucositis

Melatonin exerts various physiological effects through melatonin receptors and their ability to scavenge free radicals. Radiotherapy is a common treatment for head and neck tumors, but stomatitis, a side effect affecting irradiated oral mucosa, can impact treatment outcomes. This study investigated the preventive effect of melatonin, a potent free radical scavenger, on radiation-induced oral mucositis. Mice were irradiated with 15 Gy of X-ray radiation to the head and neck, and the oral mucosa was histologically compared between a melatonin-administered group and a control group. The results showed that radiation-induced oral mucositis was suppressed in mice administered melatonin before and after irradiation. It was suggested that the mechanism involved the inhibition of apoptosis and the inhibition of DNA damage. From these findings, we confirmed that melatonin has a protective effect against radiation-induced oral mucositis.

Improved Method for Dental Pulp Stem Cell Preservation and Its Underlying Cell Biological Mechanism

Dental pulp stem cells (DPSCs) are considered a valuable cell source for regenerative medicine because of their high proliferative potential, multipotency, and availability. We established a new cryopreservation method (NCM) for collecting DPSCs, in which the tissue itself is cryopreserved and DPSCs are collected after thawing. We improved the NCM and developed a new method for collecting and preserving DPSCs more efficiently. Dental pulp tissue was collected from an extracted tooth, divided into two pieces, sandwiched from above and below using cell culture inserts, and cultured. As a result, the cells in the pulp tissue migrated vertically over time and localized near the upper and lower membranes over 2-3 days. With regard to the underlying molecular mechanism, SDF1 was predominantly involved in cell migration. This improved method is valuable and enables the more efficient collection and reliable preservation of DPSCs. It has the potential to procure a large number of DPSCs stably.

A New Induction Method for the Controlled Differentiation of Human-Induced Pluripotent Stem Cells Using Frozen Sections

Considering that every tissue/organ has the most suitable microenvironment for its functional cells, controlling induced pluripotent stem cell (iPSC) differentiation by culture on frozen sections having a suitable microenvironment is possible. Induced PSCs were cultured on frozen sections of the liver, the brain, the spinal cord, and cover glasses (control) for 9 days. The iPSCs cultured on the sections of the liver resembled hepatocytes, whereas those on sections of the brain and the spinal cord resembled neuronal cells. The percentage of hepatocytic marker-positive cells in the iPSCs cultured on the sections of the liver was statistically higher than that of those in the iPSCs cultured on the sections of the brain and the spinal cord or on cover glasses. In contrast, the iPSCs cultured on the sections of the brain and the spinal cord revealed a high percentage of neural marker-positive cells. Thus, iPSCs can be differentiated into a specific cell lineage in response to specific factors within frozen sections of tissues/organs. Differentiation efficacy of the frozen sections markedly differed between the iPSC clones. Therefore, our induction method could be simple and effective for evaluating the iPSC quality.

Leptin promotes wound healing in the oral mucosa

INTRODUCTION

Leptin, a 16 kDa circulating anti-obesity hormone, exhibits many physiological properties. Recently, leptin was isolated from saliva; however, its function in the oral cavity is still unclear. In this study, we investigated the physiological role of leptin in the oral cavity by focusing on its effect on wound healing in the oral mucosa.

METHODS

Immunohistochemical analysis was used to examine the expression of the leptin receptor (Ob-R) in human/rabbit oral mucosa. To investigate the effect of leptin on wound healing in the oral mucosa, chemical wounds were created in rabbit oral mucosa, and leptin was topically administered to the wound. The process of wound repair was histologically observed and quantitatively analyzed by measuring the area of ulceration and the duration required for complete healing. The effect of leptin on the proliferation, differentiation and migration of human oral mucosal epithelial cells (RT7 cells) was investigated using crystal violet staining, reverse transcription polymerase chain reaction (RT-PCR) and a wound healing assay, respectively.

RESULTS

Ob-R was expressed in spinous/granular cells in the epithelial tissue and vascular endothelial cells in the subepithelial connective tissue of the oral mucosa. Topical administration of leptin significantly promoted wound healing and shortened the duration required for complete healing. Histological analysis of gingival tissue beneath the ulceration showed a denser distribution of blood vessels in the leptin-treated group. Although the proliferation and differentiation of RT7 cells were not affected by leptin, the migration of these cells was accelerated in the presence of leptin.

CONCLUSION

Topically administered leptin was shown to promote wound healing in the oral mucosa by accelerating epithelial cell migration and enhancing angiogenesis around the wounded area. These results strongly suggest that topical administration of leptin may be useful as a treatment to promote wound healing in the oral mucosa.

Virtual Active Touch: Perception of Virtual Gratings Wavelength through Pointing-Stick Interface

Tactile feedback enhances the usability and enjoyment of human-computer interfaces. Many feedback techniques have been devised to present tactile stimuli corresponding to a user's hand movements taking account of the concept of active touch. However, hand movements may not necessarily be required for achieving natural tactile feedback. Here, we propose a virtual-active-touch method that achieves haptic perception without actual/direct hand movements. In this method, a cursor manipulated by a force-input device is regarded as a virtual finger of the operator on the screen. Tactile feedback is provided to the operator in accordance with cursor movements. To validate the translation of virtual roughness gratings, we compare the virtual-active-touch interface with an interface that involves actual hand movements. By using the appropriate force-to-velocity gain for the pointing-stick interface, we show that the virtual-active-touch method presents the surface wavelengths of the gratings, which is a fundamental property for texture roughness, and that the gain significantly influences the textures experienced by the operators. Furthermore, we find that the perceived wavelengths of objects scaled and viewed on a small screen are skewed. We conclude that although some unique problems remain to be solved, we may be able to perceive the surface wavelengths solely with the intentions of active touch through virtual-active-touch interfaces.

Vibrotactile Stimuli Applied to Finger Pads as Biases for Perceived Inertial and Viscous Loads

The perception of the mass and viscosity of an object is based on the dynamic forces applied to our hands when we jiggle or lift the object [1], [2], [3]. This force is commonly assumed to be sensed by kinetic receptors [4] in our muscles or tendons. When jiggling objects, we also experience the cutaneous deformation of our finger pads. In this study, we show that the dynamic vibration on the finger pad influences our perception of mass and viscosity. We experimentally confirm that the vibration on the finger pad, that synchronizes with the hand's accelerations or velocities, enhances the perceived changes in the mass or viscosity when the vibrotactile stimuli and the changes in the mass and viscosity are in the same perceptual direction. For example, when the increased mass and an acceleration-synchronized tactile stimulus-which is a positive bias for the mass-are simultaneously presented to the experiment participants, they respond that the perceived increase in the mass is enhanced. In contrast, when the tactile and proprioceptive stimuli are in perceptually opposite directions, the vibrotactile stimuli cancel the perceived changes in the mass and viscosity. In particular, the effect of the velocity-synchronized vibration on perception is stronger than the effect of the actual viscosity.

Bleeding tendency and impaired platelet function in a patient carrying a heterozygous mutation in the thromboxane A2 receptor

BACKGROUND

Thromboxane A(2) receptor (TXA(2)R) abnormality appears to dominantly disturb platelet function.

OBJECTIVES

To reveal a molecular genetic defect in a patient with TXA(2)R abnormality and investigate the mechanism for the impaired response to TXA(2).

PATIENT

The proband (OSP-2, PT) was a 7-year-old Japanese girl, suffering from repeated mucocutaneous bleeding.

METHODS AND RESULTS

U46619 (2.5 and 10 μm)-induced platelet aggregation was remarkably impaired in the proband and her father. Immunoblots showed that TXA(2)R expression levels in their platelets were approximately 50% of controls, and nucleotide sequence analysis revealed that they were heterozygous for a novel mutation, c.167dupG in the TXA(2)R cDNA. Expression studies using Chinese hamster ovary (CHO) cells indicated that the mutation is responsible for the expression defect in TXA(2)R. We then examined α(IIb)β(3) activation by employing an initial velocity analysis and revealed that U46619 failed to induce a sustained α(IIb)β(3) and Rap1B activation in the proband. In addition, platelet secretion as monitored by P-selectin expression was markedly impaired in response to U46619 but not to ADP. The interaction between secreted ADP and P2Y(12) has been shown to play a critical role in the sustained α(IIb)β(3) activation (Kamae et al. J Thromb Haemost 2006; 4: 1379). As expected, small amounts of exogenous ADP (0.5 μm) partially restored the sustained α(IIb)β(3) activation induced by U46619.

CONCLUSION

Our present data strongly suggest that the impaired platelet activation in response to U46619 in the heterozygous subject for the TXA(2)R mutation is, at least in part, as a result of the decrease in ADP secretion.

Challenges to the Transition to the Practical Application of IPMC as Artificial-Muscle Actuators

In recent years, electroactive polymers (EAP) materials have gained recognition as potential actuators with unique capabilities having the closest performance resemblance to biological muscles. Ion-exchange membrane metallic composites (IPMC) are one of the EAP materials with such a potential. The strong bending that is induced by IPMC offers attractive actuation for the construction of various mechanisms. Examples of applications that were conceived and investigated for planetary tasks include a gripper and wiper. The development of the wiper for dust removal from the window of a miniature rover, planned for launch to an asteroid, is the subject of this reported study. The application of EAP in space conditions is posing great challenge due to the harsh operating conditions that are involved and the critical need for robustness and durability. The various issues that can affect the application of IPMC were examined including operation in vacuum, low temperatures, and the effect of the electromechanical and ionic characteristics of IPMC on its actuation capability. The authors introduced highly efficient IPMC materials, mechanical modeling, unique elements and protective coatings in an effort to enhance the applicability of IPMC as an actuator of a planetary dust-wiper. Results showed that the IPMC technology is not ready yet for practical implementation due to residual deformation that is introduced under DC activation and the difficulty to protect the material ionic content over the needed 3-years durability. Further studies are under way to overcome these obstacles and other EAP materials are also being considered as alternative bending actuators.

Possible involvement of maspin in tooth development

Maspin is a 42 kDa serine protease inhibitor that possesses tumor suppressive and anti-angiogenic activities. Despite of a huge amount of data concerning the expression pattern of maspin in various tissues and its relevance to the biological properties of a variety of human cancer cells, little is known on the maspin expression in skeletal and tooth tissues. Recently, we reported that maspin may play an important role in extracellular matrix formation in bone by enhancing the accumulation of latent TGF-β in the extracellular matrix. This study was performed to elucidate the possible role of maspin in tooth development. First, an immunohistochemical analysis for human tooth germs at the late bell stage showed the expression of maspin by active ameloblasts and odontoblasts that were forming enamel and dentin, respectively. During rat tooth development, maspin expression was observed for the first time in inner and outer enamel epithelial cells and dental papilla cells at early bell stage. The neutralizing anti-maspin antibody inhibited the proper dental tissue formation in organ cultures of mandibular first molars obtained from 21-day-old rat embryos. In addition, the proliferation of HAT-7 cells, a rat odontogenic epithelial cell line, and human dental papilla cells were suppressed in a dose-dependent manner with anti-maspin antibody. Moreover, RT-PCR analysis showed that the expression of mRNA for tooth-related genes including dentin matrix protein 1, dentin sialophosphoprotein and osteopontin in human dental papilla cells was inhibited when treated with anti-maspin antibody. These findings suggest that maspin expressed in ameloblasts and odontoblasts plays an important physiological role in tooth development through the regulation of matrix formation in dental tissues.

Detectability and Perceptual Consequences of Delayed Feedback in a Vibrotactile Texture Display

This study estimated the maximum allowable system latency for haptic displays that produce tactile stimuli in response to the hand movements of users. In Experiment 1, two types of detection thresholds were estimated for the time delay of stimuli through psychophysical experiments involving 13 participants. One was a threshold for the users to notice the existence of a time delay. The other was a threshold for the users to experience changes in the perceived textures in comparison with stimuli with no time delay. The estimated thresholds were approximately 60 and 40 ms, respectively. In interviews, the participants reported that they experienced various types of subjective changes due to the time delay. In Experiment 2, the types of subjective sensations that might be altered by the time delay were investigated. The time delays were controlled based on the acceleration of the hand motions of the participants. The participants evaluated the differences in the perceived textures between the stimuli with a controlled time delay and ones with no delay. The results indicated that the participants associated the time-delayed stimuli with changes in mechanical parameters such as kinetic friction coefficient in addition to changes in the perceived roughness of the textures.

Critical role of ADP interaction with P2Y12 receptor in the maintenance of alpha(IIb)beta3 activation: association with Rap1B activation

OBJECTIVE

Platelet integrin alpha(IIb)beta3 plays a crucial role in platelet aggregation, and the affinity of alpha(IIb)beta3 for fibrinogen is dynamically regulated. Employing modified ligand-binding assays, we analyzed the mechanism by which alpha(IIb)beta3 maintains its high-affinity state.

METHODS AND RESULTS

Washed platelets adjusted to 50 x 10(3) microL(-1) were stimulated with 0.2 U mL(-1) thrombin or 5 microm U46619 under static conditions. After the completion of alpha(IIb)beta3 activation and granule secretion, different kinds of antagonists were added to the activated platelets. The activated alpha(IIb)beta3 was then detected by fluorescein isothiocyanate (FITC)-labeled PAC1. The addition of 1 mum AR-C69931MX (a P2Y12 antagonist) or 1 mm A3P5P (a P2Y1 antagonist) disrupted the sustained alpha(IIb)beta3 activation by approximately 92% and approximately 38%, respectively, without inhibiting CD62P or CD63 expression. Dilution of the platelet preparation to 500 microL(-1) also disrupted the sustained alpha(IIb)beta3 activation, and the disruption by such dilution was abrogated by the addition of exogenous adenosine 5'-diphosphate (ADP) in a dose-dependent fashion. The amounts of ADP released from activated platelets determined by high-performance liquid chromatography were compatible with the amounts of exogenous ADP required for the restoration. We next examined the effects of antagonists on protein kinase C (PKC) and Rap1B activation induced by 0.2 U mL(-1) thrombin. Thrombin induced long-lasting PKC and Rap1B activation. AR-C69931MX markedly inhibited Rap1B activation without inhibiting PKC activation.

CONCLUSIONS

Our data indicate that the continuous interaction between released ADP and P2Y12 is critical for the maintenance of alpha(IIb)beta3 activation.

Analyses of genetic abnormalities in type I CD36 deficiency in Japan: identification and cell biological characterization of two novel mutations that cause CD36 deficiency in man

To elucidate genetic abnormalities in type I CD36 deficiency, we analyzed 28 Japanese subjects whose platelets and monocytes/macrophages lacked CD36 on their surface. We identified two novel mutations in the CD36 gene. One was a complex deletion/insertion mutation, in which 3 bp, GAG, were deleted at nucleotide (nt) 839-841, and 5 bp, AAAAC, were inserted at the same position (839-841del-->insAAAAC). Mutation 839-841del-->insAAAAC led to a frameshift and appearance of a premature stop codon; it was also accompanied with a marked reduction in the amount of CD36 mRNA. The other was a 12-bp deletion at nt 1438-1449 (1438-1449del) accompanied with or without skipping of exon 9 (nt 959-1028). Mutation 1438-1449del led to an inframe 4-amino-acid deletion, whereas exon 9 skipping led to a frameshift and the appearance of a premature stop codon. Expression assay revealed that both 1438-1449del and exon 9 skipping directly caused impairment of the surface expression of CD36. A survey of the five known mutations including 839-841del-->insAAAAC and 1438-1449del in type I CD36-deficient subjects demonstrated that the five mutations covered more than 90% of genetic defects among them and that the substitution of T for C at nt 478 (478C-->T) was the most common mutation with more than 50% frequency. However, none of the four subjects that possessed isoantibodies against CD36 had 478C-->T, suggesting that 478C-->T prevents the production of isoantibodies against CD36.

Ligand binding to integrin alpha(v)beta(3) requires tyrosine 178 in the alpha(v) subunit

Integrin alpha(v)beta(3) has been implicated in angiogenesis and other biological processes. However, the ligand-binding sites in alpha(v), a non-I-domain alpha subunit, remain to be identified. Recently in alpha(IIb), the other partner of the beta(3) subunit, several discontinuous residues important for ligand binding were identified in the predicted loops between repeats 2 and 3 (W3 4-1 loop) and within repeat 3 (W3 2-3 loop). Based on these findings, alanine-scanning mutagenesis in 293 cells was used to investigate the role of these loops (cysteine [C]142-C155 and glycine [G]172-G181) of alpha(v) in ligand binding. Wild-type alpha(v)beta(3) was able to bind soluble fibrinogen following integrin activation either by 0.5 mM manganese dichloride (MnCl(2)) or a mutation of beta(3) threonine (T)562 to asparagine. However, mutation of tyrosine (Y)178 to alanine in the predicted G172-G181 loop of alpha(v) abolished fibrinogen binding, and alanine (A) substitutions at adjacent residues phenylalanine (F)177 and tryptophan (W)179 had a similar effect. Cells expressing Y178Aalpha(v) also failed to bind to immobilized fibrinogen. Moreover, the Y178A mutation abolished the binding of WOW-1 Fab, a monovalent ligand-mimetic anti-alpha(v)beta(3) antibody, and the expression of beta(3) ligand-induced binding sites (LIBS) induced by arginine-glycine-aspartic acid-tryptophan (RGDW). In sharp contrast to the data obtained with alpha(IIb), none of the mutations in the predicted W3 4-1 loop in alpha(v) impaired ligand binding. These results implicate alpha(v) Y178 in ligand binding to alpha(v)beta(3), and they suggest that there are key structural differences in the adhesive ligand-binding sites of alpha(v)beta(3) and alpha(IIb)beta(3).

Anti-alphavbeta3 antibodies in chronic immune thrombocytopenic purpura

In chronic immune thrombocytopenic purpura (ITP), anti-GPIIb-IIIa (alphaIIbbeta3) autoantibodies have been detected in serum and/or platelet-associated IgG (PAIgG) and considered as one of the major causes. We examined whether anti-alphavbeta3 antibodies might be present in ITP cases because of the similarity between alphavbeta3 and GPIIb-IIIa (alphaIIbbeta3). Modified antigen capture ELISA (MACE) using human umbilical vein endothelial cells (HUVEC) showed the presence of serum anti-alphavbeta3 antibodies in 23 of 80 ITP patients (29%). Cross-adsorption studies between platelets and HUVEC demonstrated that most of anti-alphavbeta3 and anti-GPIIb-IIIa antibodies exclusively reacted with alphavbeta3 and GPIIb-IIIa, respectively. Platelet-associated anti-GPIIb-IIIa antibodies did not react with alphavbeta3, either. Interestingly, patients having anti-alphavbeta3 antibodies showed significantly lower platelet counts than negative patients. These results indicate the serum anti-alphavbeta3 antibodies are different ones from the classical anti-GPIIb-IIIa (alphaIIbbeta3) antibodies and would provide a new insight into the pathophysiology of ITP as well as the autoantigenic epitopes on beta3 integrins.

[Comparison of reticulated platelet count with plasma glycocalicin concentration as a marker of platelet turnover in patients with thrombocytopenic disorders]

Measurements of plasma glycocalicin (GC) and reticulated platelets (RP) have been reported to be useful for classifying thrombocytopenic disorders. However, there have been no reports comparing the clinical usefulness of the two methods. We measured GC and RP levels simultaneously in 39 patients with idiopathic thrombocytopenic purpura (ITP), 15 patients with aplastic anemia (AA), and 17 patients with hypoplastic thrombocytopenia (HypoT) due to chemotherapy. The GC index (GC level normalized for the individual platelet count) and the percentage of RP (%RP), a parameter of platelet life span, were very high (7.5 +/- 11.4 and 20.8 +/- 13.0%, respectively) in patients with ITP as compared with those of healthy subjects (1.3 +/- 0.5 and 7.9 +/- 2.5%, respectively). However, 6 AA patients and 14 HypoT patients, in whom platelet life span is thought to be normal, also had an elevated GC index, suggestive of a false positive result. The RP, a parameter of platelet production, was low in all AA and HypoT patients except for one in each case. However, the GC level, an additional parameter of platelet production, was normal in 4 AA and 8 HypoT patients, indicating that it is not a sensitive indicator. We conclude that the RP and %RP are more feasible markers of thrombopoiesis and platelet life span, respectively, than the GC level and GC index.

The 2-phenylbenzotriazole-type water pollutant PBTA-2 has cytochalasin B-mimetic activity

The 2-phenylbenzotriazole (PBTA)-type water pollutant, 2-[2-(acetylamino)-4-[N-(2-cyanoethyl)ethylamino]-5-methoxyphenyl]-5- amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2), has been recently identified in samples from the Nishitakase River in Kyoto, Japan, and shows potent mutagenic activities in Salmonella typhimurium in the presence of a microsomal metabolizing system (S9 mix). In the present study, we conducted the in vitro micronucleus (MN) test on PBTA-2 in the absence and presence of S9 mix in two Chinese hamster cell lines, CHL and V79-MZ. In the MN test, PBTA-2 was weakly positive in CHL cells and strongly positive in V79-MZ cells. Because the positive results were accompanied by a statistically significant increase in the number of polynuclear (PN) and/or mitotic (M) cells, we examined treated cells in metaphase to see if numerical chromosome aberrations were being induced. We found that PBTA-2 induces polyploidy in both CHL and V79-MZ cells. A detailed analysis of MN preparations showed that in CHL cells, PBTA-2 predominantly induces equal-sized binucleated cells. Rhodamine phalloidin staining revealed that PBTA-2 causes actin filament abnormalities in both cell lines similar to those caused by cytochalasin B. Cytochalasin B induced PN cells predominantly and dose dependently, and almost all the cells were equal-sized and binucleate. The results suggest that PBTA-2 has cytochalasin B-mimetic activity, although agents affecting actin filaments, such as cytochalasins, phallotoxins and chloropeptide, have been derived only from molds so far. This study also suggests that our MN test protocol may be used to identify chemicals that have cytochalasin B-mimetic activity as well as those that induce numerical aberrations.

Involvement of unique leucine-zipper motif of PSD-Zip45 (Homer 1c/vesl-1L) in group 1 metabotropic glutamate receptor clustering

Several scaffold proteins for neurotransmitter receptors have been identified as candidates for receptor targeting. However, the molecular mechanism underlying such receptor clustering and targeting to postsynaptic specializations remains unknown. PSD-Zip45 (also named Homer 1c/vesl-1L) consists of the NH(2) terminus containing the enabled/VASP homology 1 domain and the COOH terminus containing the leucine zipper. Here, we demonstrate immunohistochemically that metabotropic glutamate receptor 1alpha (mGluR1alpha) and PSD-Zip45/Homer 1c are colocalized to synapses in the cerebellar molecular layer but not in the hippocampus. In cultured hippocampal neurons, PSD-Zip45/Homer1c and N-methyl-D-aspartate receptors are preferentially colocalized to dendritic spines. Cotransfection of mGluR1alpha or mGluR5 and PSD-Zip45/Homer 1c into COS-7 cells results in mGluR clustering induced by PSD-Zip45/Homer 1c. An in vitro multimerization assay shows that the extreme COOH-terminal leucine zipper is involved in self-multimerization of PSD-Zip45/Homer 1c. A clustering assay of mGluRs in COS-7 cells also reveals a critical role of this leucine-zipper motif of PSD-Zip45/Homer 1c in mGluR clustering. These results suggest that the leucine zipper of subsynaptic scaffold protein is a candidate motif involved in neurotransmitter receptor clustering at the central synapse.

[The sensitivity, specificity and predictive value of PAIgG, reticulated platelets, thrombopoietin levels, and platelet size for the differential diagnosis of thrombocytopenia]

We evaluated measurements of PAIgG, reticulated platelets (RP), plasma thrombopoietin (TPO) levels, and platelet size to determine whether these parameters were useful for the differential diagnosis of idiopathic thrombocytopenic purpura (ITP), aplastic anemia (AA), and hypoplastic thrombocytopenia (HypoT). The percentage of RP (%RP) in patients with ITP was significantly higher (25.2 +/- 11.0%, P < 0.001) than in normal subjects (7.9 +/- 2.8), and the sensitivity, specificity, and predictive value of %RP in diagnosing ITP were 82%, 95%, 96%, respectively. On the other hand, TPO levels in patients with AA and HypoT were significantly higher (355.5 +/- 218.7 pg/ml, P < 0.001, and 376.4 +/- 347.2, P < 0.001, respectively) than in normal subjects (36.7 +/- 23.0). The sensitivity, specificity, and predictive value of TPO in diagnosing AA and HypoT were 88%, 89% and 86%, respectively. We also sought to determine whether the simultaneous measurement of %RP and TPO improved their value in the differential diagnosis of ITP, AA, and HypoT. However, simultaneous measurement did not yield significant improvements in sensitivty, specificity, or predictive value. These results indicated that measurements of %RP will suffice for the diagnosis of ITP, and that measurements of TPO are adequate for the diagnosis of AA and HypoT.

A mutation in the extracellular cysteine-rich repeat region of the beta3 subunit activates integrins alphaIIbbeta3 and alphaVbeta3

Inside-out signaling regulates the ligand-binding function of integrins through changes in receptor affinity and/or avidity. For example, alphaIIbbeta3 is in a low-affinity/avidity state in resting platelets, and activation of the receptor by platelet agonists enables fibrinogen to bind. In addition, certain mutations and truncations of the integrin cytoplasmic tails are associated with a high-affinity/avidity receptor. To further evaluate the structural basis of integrin activation, stable Chinese hamster ovary (CHO) cell transfectants were screened for high-affinity/avidity variants of alphaIIbbeta3. One clone (AM-1) expressed constitutively active alphaIIbbeta3, as evidenced by (1) binding of soluble fibrinogen and PAC1, a ligand-mimetic antialphaIIbbeta3 antibody; and (2) fibrinogen-dependent cell aggregation. Sequence analysis and mutant expression in 293 cells proved that a single amino acid substitution in the cysteine-rich, extracellular portion of beta3(T562N) was responsible for receptor activation. In fact, T562N also activated alphaVbeta3, leading to spontaneous binding of soluble fibrinogen to 293 cells. In contrast, neither T562A nor T562Q activated alphaIIbbeta3, suggesting that acquisition of asparagine at residue 562 was the relevant variable. T562N also led to aberrant glycosylation of beta3, but this was not responsible for the receptor activation. The binding of soluble fibrinogen to alphaIIbbeta3(T562N) was not sufficient to trigger tyrosine phosphorylation of pp125(FAK), indicating that additional post-ligand binding events are required to activate this protein tyrosine kinase during integrin signaling. These studies have uncovered a novel gain-of-function mutation in a region of beta3 intermediate between the ligand-binding region and the cytoplasmic tail, and they suggest that this region is involved in integrin structural changes during inside-out signaling.

[Reticulated platelet determination: methodologies and applications for the evaluation of thrombocytopenic disorders]

Reticulated platelets retain some residual mRNA in their cytoplasm and are thought to be newly produced platelets. In recent years, it has been reported that the reticulated platelet count (RP) correlates well with platelet production. For that reason, the measurement of RP (%) is considered useful for analyses of platelet kinetics and differential diagnoses of thrombocytopenic disorders. However, certain technical difficulties exist because fluorochrome thiazole orange (TO), which is used for staining purposes, stains platelet granules nonspecifically, and so far, only a few reports have documented the study of precision staining techniques. We evaluated staining criteria precisely in an effort to solve the issue of nonspecific staining by TO, and concluded that the important points for effective staining were (1) fixation of platelets, (2) 1:8 dilution of TO (ReticCount), (3) incubation for 1 to 2 hours, and (4) the capture of platelets using anti-CD42b monoclonal antibody. We stained reticulated platelet samples by the above method and achieved intra-assay reproducibility of 3.4-5.1% RP (%) in normal subjects was 8.7 +/- 2.2%. It was significantly higher (23.6 +/- 13.3%) in patients with idiopathic thrombocytopenic purpura (ITP), and elevated in 87% of all evaluated ITP patients. Our method is sensitive, provides reproducible results, and can be effectively utilized for the analysis of platelet kinetics and differential diagnosis of thrombocytopenia.

Phenotype-dependent expression of alpha-smooth muscle actin in visceral smooth muscle cells

Alpha-Smooth muscle actin is one of the molecular markers for a phenotype of vascular smooth muscle cells, because the actin is a major isoform expressed in vascular smooth muscle cells and its expression is upregulated during differentiation. Here, we first demonstrate that the phenotype-dependent expression of this actin in visceral smooth muscles is quite opposite to that in vascular smooth muscles. This actin isoform is not expressed in adult chicken visceral smooth muscles including gizzard, trachea, and intestine except for the inner layer of intestinal muscle layers, whereas its expression is clearly detected in these visceral smooth muscles at early stages of the embryo (10-day-old embryo) and is developmentally downregulated. In cultured gizzard smooth muscle cells maintaining a differentiated phenotype, alpha-smooth muscle actin is not detected while its expression dramatically increases during serum-induced dedifferentiation. Promoter analysis reveals that a sequence (-238 to -219) in the promoter region of this actin gene acts as a novel negative cis-element. In conclusion, the phenotype-dependent expression of alpha-smooth muscle actin would be regulated by the sum of the cooperative contributions of the negative element and well-characterized positive elements, purine-rich motif, and CArG boxes and their respective transacting factors.

CD36 mediates long-chain fatty acid transport in human myocardium: complete myocardial accumulation defect of radiolabeled long-chain fatty acid analog in subjects with CD36 deficiency

Long-chain fatty acids (LCFA) are the major energy substrate for heart and their oxidation is important for achieving maximal cardiac work. However, the mechanism of uptake of LCFA by myocardium has not been clarified. We previously reported that bovine myocardial LCFA transporter has a sequence homology to human CD36. Clinically, total defect of myocardial uptake of radiolabeled long-chain fatty acid analog [123I-BMIPP: Iodine-123 15-(p-iodophenyl)-(R,S)-methylpentadecanoic acid] has been reported in some restricted cases, but the etiology has not been clarified. In the present study, we analyzed CD36 expression and CD36 gene in subjects who showed total lack of myocardial 123I-BMIPP accumulation, and, vice versa, evaluated myocardial 123I-BMIPP uptake in subjects with CD36 deficiency. Four unrelated subjects were evaluated, Two were found to have negative myocardial LCFA accumulation by 123I-BMIPP scintigraphy, after which the expression of CD36 on their platelets and monocytes was analyzed. Remaining two subjects were identified as CD36 deficiency by screening, then 123I-BMIPP scintigraphy was performed. Expression of CD36 on platelets and monocytes was measured by flow cytometric analysis. The molecular defects responsible for CD36 deficiency was detected by allele-specific restriction enzyme analysis. CD36 expression was totally deficient in all 4 subjects on both platelets and monocytes. Two subjects were homozygous for a 478C-->T mutation. One was heterozygous for the dinucleotide deletion of exon V and single nucleotide insertion of exon X, and remaining one was considered to be heterozygous for the dinucleotide deletion of exon V and an unknown gene abnormality. All cases demonstrated a completely negative accumulation of myocardial LCFA despite of normal myocardial perfusion, which was evaluated by thallium scintigraphy. In addition, all cases demonstrated apparently normal hepatic LCFA accumulation Thus, these findings suggested that CD36 acts as a major myocardial specific LCFA transporter in humans.

Involvement of Na+/Ca2+ exchanger in inside-out signaling through the platelet integrin IIbbeta3

The platelet integrin IIbbeta3 has become a new target for the treatment of pathological thrombosis. It becomes apparent that the affinity of IIbbeta3 for its ligands is dynamically regulated by inside-out signaling. However, the components that couple diverse intracellular signals to the cytoplasmic domains of IIbbeta3 remain obscure. Employing a chymotrypsin-induced IIbbeta3 activation model, we previously proposed the hypothesis that Na+/Ca2 + exchanger (NCX) may be involved in inside-out signaling (Shiraga et al: Blood 88:2594, 1996). In the present study, employing two unrelated Na+/Ca2+ exchange inhibitors, 3',4'-dichlorobenzamil (DCB) and bepridil, we investigated the role of NCX in platelet activation induced by various agonists in detail. Both inhibitors abolished platelet aggregation induced by all agonists examined via the inhibition of IIbbeta3 activation. Moreover, these inhibitors abolished IIbbeta3 activation induced by phorbol 12-myristate 13-acetate or A23187. On the other hand, neither of these inhibitors showed apparent inhibitory effects on protein phosphorylation of pleckstrin or myosin light chain, or an increase in intracellular calcium ion concentrations evoked by 0.1 U/mL thrombin. These effects of the NCX inhibitors are in striking contrast to those of protein kinase C inhibitor, Ro31-8220. Biochemical and ultrastructural analyses showed that NCX inhibitors, particularly DCB, made platelets "thrombasthenic". These findings suggest that the NCX is involved in the common steps of inside-out signaling through integrin IIbbeta3.

Isolation of PSD-Zip45, a novel Homer/vesl family protein containing leucine zipper motifs, from rat brain

Using monoclonal antibody against the 45 kDa postsynaptic density protein, we isolated a novel isoform of Homer/vesl. The NH2-terminal region containing a PDZ domain of this protein is identical to that of Homer/vesl, and the COOH-terminal region containing unique leucine zippers shows self-multimerization. We named this protein PSD-Zip45. In addition to specific binding of PSD-Zip45 mediated by a PDZ domain to the metabotropic glutamate receptors 1alpha or 5, the distribution of PSD-Zip45 transcripts is highly consistent with that of metabotropic glutamate receptor transcripts. The PSD-Zip45 is, therefore, the first candidate as receptor anchoring proteins containing leucine zipper motifs in the central nervous system.

A Gln747-->Pro substitution in the IIb subunit is responsible for a moderate IIbbeta3 deficiency in Glanzmann thrombasthenia

To clarify a molecular defect responsible for moderate alphaIIb beta3 deficiency, we examined two unrelated patients, MT and MS, suffering from type II and type I Glanzmann thrombasthenia (GT), respectively. Sequence analysis of polymerase chain reaction (PCR) fragments derived from platelet mRNA showed a single A-->C substitution at nucleotide (nt) 2334 leading to a Gln747--> Pro in alphaIIb in both patients. Allele-specific restriction enzyme analysis (ASRA) of genomic DNA demonstrated that patient MT was homozygous for the Gln747-->Pro substitution and patient MS was compound heterozygous for this substitution and for an RNA splice mutation at the consensus sequence of the splice acceptor site of exon 18 (AG-->AA). Furthermore, ASRA showed that, among 17 unrelated Japanese GT patients, this Gln747-->Pro substitution was detected in 4 patients, including MT and MS (homozygous, 2 patients; heterozygous, 2 patients). Cotransfection of Pro747alphaIIb and beta3 constructs into 293 cells resulted in moderate reduction in the amount of alphaIIb beta3 within the transfected cells as well as on the cell surface. However, Pro747alphaIIb beta3 bound the ligand mimetic monoclonal antibody (MoAb) PAC-1 after activation of alphaIIb beta3 by the MoAb PT25-2, suggesting that the mutant alphaIIb beta3 possesses the ligand-binding function. The association between the mutant proalphaIIb and beta3 was not disturbed. Surface labeling and pulse chase study showed that the Gln747-->Pro substitution moderately impaired both intracellular transport of the alphaIIb beta3 heterodimers to the Golgi apparatus and endoproteolytic cleavage of proalphaIIb into heavy and light chains. By contrast, replacement of Gln747 with Ala by mutagenesis did not impair alphaIIbbeta3 expression on the cell surface. These results suggest that the presence of Pro, rather than the absence of Gln, at amino acid residue 747 on alphaIIb is responsible for moderate alphaIIbbeta3 deficiency.

A two-amino acid insertion in the Cys146- Cys167 loop of the alphaIIb subunit is associated with a variant of Glanzmann thrombasthenia. Critical role of Asp163 in ligand binding

The ligand binding site(s) of the alpha subunit of integrin alphaIIb beta3 (GPIIb-IIIa), a prototypic non-I domain integrin, remains elusive. In this study, we have characterized a Japanese variant of Glanzmann thrombasthenia, KO, whose platelets express normal amounts of alphaIIb beta3. KO platelets failed to bind the activation-independent ligand-mimetic mAb OP-G2 and did not bind fibrinogen or the activation-dependent ligand-mimetic mAb PAC-1 following activation of alphaIIb beta3 under any condition examined. Sequence analysis of PCR fragments derived from KO platelet mRNA revealed a 6-bp insertion leading to a 2-amino-acid insertion (Arg-Thr) between residues 160 and 161 of the alphaIIb subunit. Introduction of the insertion into wild-type recombinant alphaIIb beta3 expressed in 293 cells led to the normal expression of alphaIIb beta3 having the defect in ligand binding function. The insertion is located within the small loop (Cys146-Cys167) in the third NH2-terminal repeat of the alphaIIb subunit. Alanine substitution of each of the oxygenated residues within the loop (Thr150, Ser152, Glu157, Asp159, Ser161, and Asp163) did not significantly affect expression of alphaIIbbeta3, and only Asp163AlaalphaIIb beta3 abolished the ligand binding function. In addition, Asp163AlaalphaIIb beta3 as well as KO mutant alphaIIb beta3 constitutively expressed the PMI-1 epitope. Our present data suggest that Asp163 of the alphaIIb subunit is one of the critical residues for ligand binding.

Markedly reduced expression of platelet c-mpl receptor in essential thrombocythemia

Thrombopoietin (TPO) is implicated as a primary regulator of megakaryopoiesis and thrombopoiesis through binding to the cytokine receptor c-Mpl (the product of the c-mpl proto-oncogene). In an effort to determine the pathophysiological role of TPO-c-Mpl system in essential thrombocythemia (ET), we have examined the levels of serum TPO and the expression and function of platelet c-Mpl in 17 patients with ET. In spite of extreme thrombocytosis, serum TPO levels were slightly elevated or within normal range in most, if not all, patients with ET (mean +/- SD, 1.31 +/- 1.64 fmol/mL), as compared with normal subjects (0.76 +/- 0.21 fmol/mL). Flow cytometric and Western blot analyses revealed that the expression of platelet c-Mpl was strikingly reduced in all patients with ET. Furthermore, the expression of platelet c-mpl mRNA was found to be significantly decreased in the ET patients tested. In contrast, almost identical levels of GPIIb/IIIa protein and mRNA were expressed in platelets from ET patients and normal controls. In addition to expression level, activation state of platelet c-Mpl was investigated in ET patients. Immunoblotting with anti-phosphotyrosine antibody showed that no aberrant protein-tyrosine phosphorylation was observed in platelets of ET patients before treatment with TPO, and the levels of TPO-induced protein-tyrosine phosphorylation, including c-Mpl-tyrosyl phosphorylation, roughly paralleled those of c-Mpl expression, suggesting that c-Mpl-mediated signaling pathway was not constitutively activated in platelets of ET patients. These results suggested that the TPO-c-Mpl system may not be directly linked to pathogenesis of ET, and that gene(s) mutated in ET may be important in regulating the levels of c-mpl gene expression in addition to the growth and differentiation of multipotential hematopoietic stem cells.

Circulating thrombopoietin level in chronic immune thrombocytopenic purpura

The circulating thrombopoietin (TPO) level in 43 patients with chronic immune thrombocytopenic purpura (ITP) was examined by an ELISA system. The TPO level (mean +/- SD) in ITP patients was mildly elevated (1.86 +/- 1.17 fmol/ml) compared to that in normal subjects (0.76 +/- 0.21), and was within the normal range in 30% of ITP patients. In contrast, the TPO level in patients with aplastic anaemia was very high, 12.35 +/- 6.42 fmol/ml. There was no correlation between TPO level and platelet count in ITP patients. Splenectomy was performed in two ITP patients, after which platelet counts increased to normal levels and TPO levels showed a transient increase. These data suggest that reactive TPO production against thrombocytopenia in ITP is small when compared to that in aplastic anaemia. Relative endogenous TPO deficiency may play some role in the pathophysiology of thrombocytopenia in ITP patients.

Long-continuous observation of the effects of methamphetamine on wheel-running and drinking in mice

1. Effects of methamphetamine (MAP) on wheel-running and drinking in mice, housed under 12-hr light-dark schedule (light period; 06:00-18:00), were investigated through long-continuous observation. 2. MAP (1, 2 and 4 mg/kg, s.c.) acutely increased the wheel-running and drinking for 2-4 hr in a dose-dependent manner after the administration at 11:00, midpoint of light period. 3. MAP administered at 11:00 sub-acutely suppressed the spontaneous increment during dark period (18:00-06:00) in both the behaviors. 4. Many factors, such as the time-of-day and interval of the administration as well as the dose administered, affected the behavioral suppression induced by MAP. 5. In addition to these findings, the wheel-running and drinking during the light period increased even on the days without MAP administration. 6. These results suggest that MAP have not only acute stimulant and sub-acute depressant effects, but also long-lasting effects.

Effect of OM-853, a cerebral metabolic ameliorator, on ambulatory activity and passive and active avoidance responses in mice and Mongolian gerbils

Behavioral effects of OM-853 were investigated in both mice and Mongolian gerbils. In mice, OM-853 alone produced no marked change in the ambulatory activity, although it tended to lower it at 100 mg/kg, and this drug (5-100 mg/kg, p.o.) reduced the ambulation-increasing effect of scopolamine (0.5 mg/kg, s.c.) in a dose-dependent manner. Moreover, OM-853 (50 and 100 mg/kg, p.o.) prolonged the latency times shortened by scopolamine under the passive avoidance. On the other hand, in the discrete avoidance situation, OM-853 facilitated the acquisition of shuttle avoidance at 10 and 25 mg/kg, p.o. and lever-press avoidance at 25 and 50 mg/kg, p.o. in the pre-training administration schedule, and the former at 25-100 mg/kg, p.o. and the latter at 10 and 25 mg/kg, p.o. in the post-training administration schedule. In gerbils, OM-853 (50 mg/kg, i.p.) ameliorated the learning deficit of the lever-press avoidance response induced by forebrain ischemia. The present results suggest that OM-853 has beneficial actions on some types of learning and memory in normal, scopolamine-treated and ischemic animals. The possible mechanisms involved are discussed.

Effect of chlorpromazine on mouse ambulatory activity sensitization caused by (+)-amphetamine

The development of sensitization to the ambulation-increasing effect of (+)-amphetamine (2.5 mg kg-1) was found to be dose-dependently inhibited when 1 or 2 mg kg-1 chlorpromazine was administered concomitantly, and the sensitization to (+)-amphetamine was almost completely suppressed when co-administered with 4 mg kg-1 chlorpromazine. Following a challenge dose of 2.5 mg kg-1 (+)-amphetamine, mice pretreated with (+)-amphetamine alone or with (+)-amphetamine plus 1 or 2 mg kg-1 chlorpromazine showed similar marked enhancement of the sensitization. However, mice that had been given (+)-amphetamine plus 4 mg kg-1 chlorpromazine displayed only slight enhancement of the effect compared with the activity level in saline-pretreated mice.

Circadian variation in R-THBP-induced enhancement of the ambulation-increasing effect of methamphetamine on mice

6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP), a co-factor for tyrosine hydroxylase and tryptophan hydroxylase, induces the enhancement of ambulation-increasing effect of methamphetamine on mice. In this study, we investigated the circadian variation in the interaction between R-THBP and methamphetamine by changing the time-of-day of both methamphetamine administration and pretreatment with R-THBP. The mouse's ambulatory activity was measured by a tilting-type activity cage for 4 hr. In the daytime, but not in the nighttime, the ambulation-increasing effect of methamphetamine (1 and 2 mg/kg, s.c.) was significantly enhanced by the pretreatment with R-THBP (100 mg/kg, s.c., 2 or 6 hr before). These data indicate the possibility that peripherally administered R-THBP increases the biosynthesis of catecholamine especially in the daytime.

Assessment of the ambulation-increasing effect of ketamine by coadministration with central-acting drugs in mice

The coadministration of ketamine (12.5 mg/kg, but not 3.1 mg/kg, s.c.) with methamphetamine (2 mg/kg, s.c.), cocaine (10 mg/kg, s.c.), scopolamine (0.5 mg/kg, s.c.), caffeine (10 mg/kg, s.c.) and MK-801 (0.1 mg/kg, i.p.) significantly enhanced the ambulation-increasing effects. Furthermore, in the coadministration with morphine (10 mg/kg, s.c.) and GBR-12909 (10 mg/kg, i.p.), not only 12.5 mg/kg but also 3.1 mg/kg of ketamine produced a significant enhancement. On the other hand, the ambulation-increasing effect of ketamine (12.5 mg/kg, s.c.) was significantly suppressed by ceruletide (0.01 mg/kg, i.p.), alpha-methyl-p-tyrosine (100 and 300 mg/kg, i.p. x 2), nimodipine (1 and 3 mg/kg, i.p.), haloperidol (0.03 and 0.1 mg/kg, s.c.), a low dose of apomorphine (0.1 mg/kg, s.c.), physostigmine (0.1 mg/kg, s.c.) and N6-(L-2-phenylisopropyl)-adenosine (0.1 mg/kg, s.c.). However, imipramine (20 mg/kg, i.p.), 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (100 mg/kg, s.c.), a high dose of apomorphine (0.5 mg/kg), reserpine (0.3 and 1 mg/kg, s.c.), propranolol (0.3 and 1 mg/kg, s.c.), phenoxybenzamine (3 and 10 mg/kg, s.c.) and naloxone (0.3 and 1 mg/kg, s.c.) scarcely interacted with ketamine. These results suggest that ketamine increases the ambulatory activity in mice by facilitating dopamine release from a newly synthesized pool at the presynaptic level, which is affected by a calcium-dependent mechanism.

Caffeine does not effectively ameliorate, but rather may worsen the ethanol intoxication when assessed by discrete avoidance in mice

Ethanol disrupted the discrete lever-press and shuttle avoidances in mice at doses over 1.6 and 2.4 g/kg, p.o., respectively, eliciting a dose-dependent decrease in the % of avoidance with no significant change or slight increase in the response rate. Caffeine increased the response rate of both the avoidances at the doses of 1-30 mg/kg, p.o., but disrupted the avoidance at 100 mg/kg. Caffeine (10 mg/kg) reduced the decreased % of avoidance by ethanol (1.6 and 2.4 g/kg) with a significant increase in the response rate. In contrast, the % of avoidance was significantly lower after the combined administration of ethanol (3.2 g/kg) with caffeine than after ethanol (3.2 g/kg) alone. Unlike ethanol, diazepam (2 mg/kg, s.c.) and pentobarbital (10 mg/kg, s.c.) significantly decreased both the response rate and the % of avoidance. Caffeine (10 mg/kg) ameliorated the decreased response rate and the % of avoidance produced by diazepam and pentobarbital. The present results suggest that caffeine does not effectively ameliorate, but rather may worsen the ethanol intoxication.

[Effects of nicotine on circadian rhythm of ambulatory activity and drinking in rats]

Effects of the intake of nicotine solution and/or forced administration of nicotine at a fixed time-of-day on circadian rhythm of ambulatory activity and drinking in rats were observed under various conditions. Rats showed nocturnal pattern under the light-dark cycle (L: D = 12:12, light period 6:00-18:00), and the patterns scarcely altered while the rats were given 150 micrograms/ml of nicotine solution. When a restricted feeding only for 1 h per day (10:00-11:00) was loaded to the rats, the ambulatory activity and drinking appeared in the light period, especially around the feeding time. While rats were given 15-150 micrograms/ml of nicotine solution under the restricted feeding condition, they demonstrated a marked phase-shift in the circadian rhythm in the concentration-dependent manner. Rats showed free-running rhythms with tau value of longer than 24 h under the constant red dim light condition (CRDL), and such rhythm was scarcely modified by the intake of nicotine solution of 50-150 micrograms/ml. However, when nicotine (1.5 mg/kg po), but not tap water, was administered at 10:00 every day under the CRDL condition, it also produced phase-shift which was similar to that induced by the nicotine ingestion under the redose of nicotine is administered or taken at a fixed time-of-day.

Aspects of animal experiments for evaluation of cognitive enhancers: in particular, the behavioral characteristics of Mongolian gerbils

1. The step-through passive avoidance response and discrete lever-press avoidance response of Mongolian gerbils were evaluated to point out the basic problems in the learning and memory tests in this species. 2. Mongolian gerbils exhibited extremely poor acquisition and maintenance of the passive avoidance response. 3. In contrast to the result under the passive avoidance situation, Mongolian gerbils demonstrated an excellent performance under the discrete lever-press avoidance situation. 4. A 5-min brain ischemia elicited a severe morphological damage of the pyramidal cells in hippocampal CA1 region. 5. A small part of such ischemic animals showed a deficit of acquisition of the discrete lever-press avoidance. 6. These results suggest that there is merit and demerit of the acquisition dependent on the type of tasks, and that the brain function of Mongolian gerbils may be maintained even after the ischemic operation.

Behavioral evaluation of psycho-pharmacological and psychotoxic actions of methylxanthines by ambulatory activity and discrete avoidance in mice

The behavioral effects of methylxanthines, caffeine, theophylline and theobromine, were compared by means of ambulatory activity and discrete lever-press avoidance response in mice. The single oral administration of 10-100 mg/kg of caffeine, 30-300 mg/kg of theophylline, and 10 mg/kg of theobromine significantly increased the mouse's ambulatory activity. However, 1000 mg/kg of theobromine decreased the activity. The ambulation-increasing effect of methamphetamine (2 mg/kg s.c.) was enhanced by coadministration with caffeine (3-100 mg/kg), theophylline (10-300 mg/kg), and theobromine (10-100 mg/kg). On the other hand, comparatively higher doses of caffeine (up to 30 mg/kg) slightly but significantly decreased the avoidance rate without eliciting any significant change in the response rate. Theobromine significantly decreased the response rate at higher than 300 mg/kg, and the avoidance rate at higher than 100 mg/kg. Furthermore, 1000 mg/kg of theobromine was much toxic for mice, i.e., half mice died within a few hr after the end of the 1-hr avoidance session. Theophylline did not produce any significant change in the avoidance response at the dose range of 3-300 mg/kg. These results may indicate the relative order of the centrally stimulant and/or behavioral toxic actions of methylxanthines in human.

[Behavioral study on reduction of psychotic and behavioral disorders induced by antitussive and expectorant]

Previously, we reported that psychotic and behavioral disorders induced by repeated abuse of a commercial preparation of antitussive and expectorant (BRON-W Solution, SS Pharmaceut.) was mainly due to caffeine (CAF). In order to reduce such problem, we assessed effects of a preparation containing theophylline (THEO) as the substitution of CAF, and dihydrocodeine (2HCOD), methylephedrine (MEPH) and chlorpheniramine (CPA) on ambulatory activity and discrete lever-press avoidance response in mice. It is well known that THEO is less potent in the central action than CAF, but its relaxant action on smooth muscle is about 2 times as potent as that of CAF. Therefore, the dose of THEO administered was half of that of CAF. A significant increase in the ambulatory activity was produced by the administration of CAF and/or mixed preparations, in which CAF was contained with 2HCOD, MEPH and CPA at the same doses with those in BRON 10 ml/kg. The ambulation-increasing effects of THEO and THEO-containing preparations were less potent than those of CAP and CAF-containing preparations. Furthermore, repeated 5 times administration of CAF-containing 4-drug preparation (CAF + 2HCOD+MEPH+CPA) elicited a progressive enhancement of the ambulation-increasing effect. Whereas, almost the same effect was reproduced throughout the 5 times administration of THEO-containing 4-drug preparation (THEO + 2HCOD+MEPH+CPA). The discrete lever-press avoidance response was disrupted (i.e., decrease in the avoidance rate) by CAF-containing preparations. However, THEO-containing preparations did not induce such disruption of the avoidance response, but rather improved the avoidance response (i.e., increase in the avoidance rate).(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral effects of cocoa and its main active compound theobromine: evaluation by ambulatory activity and discrete avoidance in mice

Effects of cocoa and its main CNS active constituent methylxanthine theobromine as well as caffeine were evaluated by ambulatory activity, and discrete lever-press and shuttle avoidance in mice. Cocoa (1 g/kg p.o.) and theobromine (10 mg/kg p.o.) significantly increased ambulatory activity. However, the other doses of cocoa and theobromine had no effect on the ambulatory activity. Caffeine increased ambulatory activity with the maximum action at 30 mg/kg p.o. Furthermore, cocoa (0.1, 0.3 and 1 g/kg), theobromine (3, 10, 30 and 100 mg/kg) and caffeine (3, 10, 30 and 100 mg/kg) enhanced the ambulation-increasing effect of methamphetamine (2 mg/kg s.c.). The ambulation-increasing effect of cocaine (20 mg/kg s.c.) was also enhanced by cocoa (1 g/kg), theobromine (10, 30 and 100 mg/kg) and caffeine (10, 30 and 100 mg/kg). On the other hand, comparatively higher doses of theobromine and caffeine disrupted the well established avoidance response. Thus, the avoidance rate was significantly decreased by theobromine (100 mg/kg and more) and caffeine (30 mg/kg and more) under the lever-press situation, and by theobromine (100 mg/kg and more) and caffeine (100 mg/kg) under the shuttle situation. These dose effect relationships revealed that cocoa contains about 1% theobromine. The present results indicate that we may receive the CNS action of theobromine through consumption of theobromine-containing foodstuffs or beverages in our every day life.

Sensitization to ambulation-increasing effects of cocaine after repeated administration in mice--roles of dose and interval of administration as well as experimental environments

Effects of 5 subcutaneous injections of cocaine (COC) at 10, 20 or 40 mg/kg at intervals of 1 to 7 days were investigated by placing mice individually into tilting activity cages (20cm in diameter and 18 cm height). A progressive enhancement of the ambulation-increasing effect was noted for 3 to 4 hrs after each administration, showing marked sensitization (reverse tolerance). The enhancement of the effect progressed rapidly and the maximum sensitization was observed after the 3rd to 4th administration of 10 to 20 mg/kg at intervals of 3 to 7 days. The peak effect of the enhancement was of short duration. Sensitization lasted for at least one month. However, 40 mg/kg of COC produced stereotyped behaviors concurrent with preconvulsive signs which were also enhanced by serial administration. In contrast, pretreatment with COC in a narrow environment (glass jar, 5.5 cm in diameter and 15 cm height) did not cause the enhancement to the ambulation-increasing effect of the drug. Cross-sensitization was observed from COC to methamphetamine.

[Changes in rhythmicity of ambulatory and drinking activities produced by presentation of short time lightings during dark period in rats]

It is well known that the lighting conditions affect many physiological phenomenon of laboratory animals. However, lighting conditions are frequently disturbed by investigators themselves. In this study, behavioral (ambulation and drinking) rhythmicities of rats were investigated after irregular lighting; i. e. presentation of short time lighting at 21:00, 24:00 and 3:00 for 12 min during dark period (18:00-6:00). Vaginal smear was taken and sexual cycle was observed everyday. Ambulatory and drinking activities were measured by Gundai type Ambulo-drinkometer. The irregular lighting produced the following changes in the rhythmicities: 1) increase in the ambulatory activity during 15:00-18:00 immediately before dark period 2) decrease in ambulatory activity before ovulation 3) disappearance of inhibitory phenomenon of drinking activity which was usually observed before ovulation 4) increase in the drinking activity during 6:00-9:00 immediately after dark period 5) the changes in rhythmicities of the behavioral activities lasted for more than 1 month after replacement to the regular lighting condition.

Changes in rhythmicities of ambulatory and drinking activities after hypophysectomy in rats

Effects of hypophysectomy on circadian rhythms of ambulatory and drinking activities in adult male rats were automatically recorded and investigated with a Gundai-type ambulodrinkometer. The rats were maintained under LL conditions following an LD condition. When free-running rhythms had stabilized, the rats were hypophysectomized. The rhythmicities of both activities became indistinct over the 2-4 weeks following surgery, and then gradually recovered. At this time phase shifts (phase advance) were observed in the hypophysectomized rats, while these changes were not observed in sham-operated rats. All rats entrained to lighting when kept under LD conditions again. These results suggest that the pituitary does not play an essential role in maintaining circadian rhythms, but does function as an important subordinal oscillator.

Effects of repeated MK-801 on ambulation in mice and in sensitization following methamphetamine

The noncompetitive NMDA receptor antagonist MK-801, (+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]-cyclohepten-5,10-imine , increased ambulatory activity in the mouse at doses over 0.1 mg/kg (IP). The effect was enhanced when 0.3 mg/kg MK-801 was repeatedly administered at intervals of 3-4 days. In contrast, a reduction of the effect was induced with repeated doses of 0.1 and 1 mg/kg. The mice that had repeatedly experienced 1 mg/kg MK-801 exhibited a decrease in the sensitivity to methamphetamine (2 mg/kg SC). In addition, the repeated co-administration of 1 mg/kg MK-801 with methamphetamine induced a decrease in the sensitivity to methamphetamine. No modification of methamphetamine sensitivity was elicited by 0.1 and 0.3 mg/kg MK-801 in both the single and co-administration schedules. On the other hand, established sensitization to methamphetamine was hardly affected by repeated treatment with 0.1-1 mg/kg MK-801. These results indicate that the mechanism of the inhibitory action of MK-801 on the development of methamphetamine sensitization is different from that of dopamine D2 antagonists, which may act to decrease the effective unit dose of methamphetamine and reduce ambulation-increasing effect of methamphetamine.

Characteristics of the ambulation-increasing effect of the noncompetitive NMDA antagonist MK-801 in mice: assessment by the coadministration with central-acting drugs

Characteristics of the ambulation-increasing effect of MK-801, a non-competitive NMDA antagonist, were assessed through the coadministration of MK-801 with various central-acting drugs in mice. The MK-801 (0.3 mg/kg, i.p.)-induced ambulation-increment with a slight ataxia was maximum at around 50 min, and ambulation returned to the control level at about 3 hr after the administration. At 1 mg/kg, the mouse's activity transiently increased, followed by a decrease due to a marked ataxia, which was due to neither stereotypy nor convulsion, for 20-50 min, and then increased again; the ambulation-increment continued even at 4 hr after the administration. Coadministration of MK-801 (0.3 mg/kg, i.p.) with either methamphetamine (2 mg/kg, s.c.), cocaine (20 mg/kg, s.c.), GBR-12909 (10 mg/kg, i.p.), scopolamine (0.5 mg/kg, s.c.), caffeine (10 mg/kg, s.c.) or morphine (10 mg/kg, s.c.) produced a significant enhancement of the effect. However, 0.1 mg/kg of MK-801 had no effect on the interaction with these drugs. On the other hand, the ambulation-increasing effect of MK-801 (0.3 mg/kg) was significantly reduced by haloperidol (0.3 and 0.1 mg/kg, s.c.), ceruletide (0.01 and 0.1 mg/kg, i.p.), reserpine (0.05 and 2 mg/kg, s.c., pretreatment 4 hr before) and nimodipine (1 and 3 mg/kg, i.p.), but it was scarcely modified by alpha-methyl-p-tyrosine (100 and 200 mg/kg, i.p., pretreatment 24 hr and 4 hr before), imipramine (20 mg/kg, i.p.), 6R-L-erythro-5,6,7,8-tetrahydro-biopterin (100 mg/kg, i.p.), pilocarpine (1 and 4 mg/kg, s.c.), N6-(L-2-phenylisopropyl)-adenosine (0.03 and 0.1 mg/kg, s.c.) and naloxone (1 and 5 mg/kg, s.c.).(ABSTRACT TRUNCATED AT 250 WORDS)