Time-dependent potentiation of the beta-cell is a Ca2+-independent phenomenon

When isolated rat pancreatic islets are treated with 16.7 mM glucose, a time-dependent potentiation (TDP) of insulin release occurs that can be detected by subsequent treatment with 50 mM KCl. It has been thought that TDP by glucose is a Ca2+-dependent phenomenon and only occurs when exposure to glucose is carried out in the presence of Ca2+. In contrast to this, we now demonstrate TDP under stringent Ca2+-free conditions (Ca2+-free buffer containing 1 mM EGTA). In fact, under these Ca2+-free conditions glucose caused an even stronger TDP than in the presence of Ca2+. TDP induced by glucose in the absence of extracellular Ca2+ was unaffected by inhibitors of protein kinase C (PKC). However, cerulenin or tunicamycin, two inhibitors of protein acylation, eradicated TDP without affecting glucose metabolism. The TDP by glucose was not associated with an increase in the cytosolic free Ca2+ concentration ([Ca2+]i) during subsequent treatment with high K+. Exposure of islets to forskolin under Ca(2+)-free conditions did not cause TDP despite a large increase in the cellular cAMP levels. In conclusion, glucose alone induces TDP under stringent Ca2+-free conditions when [Ca2+]i was significantly lowered. Protein acylation is implicated in the underlying mechanism of TDP.

Size-related and size-unrelated functional heterogeneity among pancreatic islets

Functional heterogeneity of pancreatic islets was systematically analyzed for the first time using freshly isolated single rat pancreatic islets. First, 60 islets were sequentially exposed to 3, 9.4, 15.6, and 24.1 mM glucose for 30 min each in incubation experiments: 36 (60%) responded in a concentration-dependent and 19 (32%) in an all-or-none manner, and 5 (8%) islets did not respond to high glucose. As a group, the larger the islet, the higher the beta cell glucose sensitivity. However, glucose-stimulated elevation of [Ca2+]i in the beta cell. insulin/glucagon ratio in the islet, and expression of glucose transporter 2, glucokinase, and pancreatic duodenal homeobox factor-1 in the beta cell were not significantly related to islet size. Second, 50 islets were stimulated with 16.7 mM glucose in perifusion. A biphasic insulin release was found in 39 (78%), and no or little first phase response in 11 (22%) islets, irrespective of the islet size. Nevertheless, when the response was plotted as a group, it was clearly biphasic. Islet size, insulin content and the amount of insulin release were positively correlated with each other. In conclusion, there are size-related and size-unrelated functional diversity among pancreatic islets. The reason for such heterogeneity remained to be determined.

Differential display analysis of mutants for the transcription factor Pdr1p regulating multidrug resistance in the budding yeast

The transcription factor Pdr1p recognizes Pdr1p/Pdr3p-response element (PDRE) to activate genes involved in multidrug resistance of the budding yeast. To identify novel targets of Pdr1p, we compared transcriptomes among the yeast cells bearing wild, disrupted and gain-of-function alleles of PDR1 using a high-throughput fluorescent differential display PCR. Consequently, we identified 20 transcripts apparently regulated by Pdr1p, which are derived from well-known target genes as well as those that have never been described in the context of drug resistance. Intriguingly, among the latter, a previously unrecognized gene bearing a small putative open reading frame preceded by a functional PDRE was found.

Lowering glucose concentrations increases cytosolic Ca2+ in orexin neurons of the rat lateral hypothalamus

Orexin neurons are specifically localized in and around the lateral hypothalamus (LH), a feeding center. Intracerebroventricular administration of orexin-A and -B stimulates feeding as well as arousal. However, little is known regarding the regulators of the orexin neuron activity. The neurons that are activated under low glucose conditions, glucose-sensitive neurons, are located in the LH and have been implicated in the control of feeding. The present study investigated the effect of glucose on the single orexin neurons isolated from the rat LH, by measuring cytosolic Ca(2+) concentration ([Ca(2+)](i)) by fura-2 microfluorometry followed by immunocytochemical staining with anti-orexin antiserum. A shift of glucose concentration form 8.3 to 2.8 mM in the superfusion solution increased [Ca(2+)](i) in 13 out of 32 orexin-immunoreactive LH neurons. The results demonstrate that glucose-sensitive orexin neurons are present in the LH and that these neurons may play a role in linking the metabolic state in the body to the orexigenic, and could also, awakening signaling in the brain.

Orexin-a activates phospholipase C- and protein kinase C-mediated Ca2+ signaling in dopamine neurons of the ventral tegmental area

The orexin-orexin receptor system has been implicated in the regulation of wakefulness/sleep states. Behavioral and psycho-stimulant effects of orexins have also been shown. Mesolimbic dopamine neurons in the ventral tegmental area (VTA) are implicated in the regulation of reward and wakefulness/sleep, In the present study, we examined the effect of orexin-A on cytosolic [Ca2+]i concentration ([Ca2+]) in the isolated rat VTA dopamine neurons. Orexin-A (10-12-10-8 M) concentration dependently increased [Ca2+]i in dopamine-containing neurons. The [Ca2+]i responses to orexin-A were inhibited under Ca2+-free conditions and by blockers of voltage-gated L- and N-type [Ca2+]i channels, nitrendipine and omega-conotoxin, respectively. The [Ca2+]i responses were also abolished by a phosphatidylcholine-specific phospholipase C inhibitor, D609, and a protein kinase C (PKC) inhibitor, calphostin C. A PKC activator, TPA, mimicked orexin-A in increasing [Ca2+]i. These results indicate that orexin-A increases [Ca2+]i in VTA dopamine neurons via phosphatidylcholine-specific PLC- and PKC-mediated activation of L- and N-type Ca2+ channels. This effect may serve as the mechanism by which orexin regulates wakefulness/sleep states and exerts its behavioral and psychostimulant effects.

PACAP activates PKA, PKC and Ca(2+) signaling cascades in rat neuroepithelial cells

Several studies have reported that the PAC(1) receptor (PAC1-R), the specific receptor for PACAP, is expressed at early developmental stages. Here, we describe that the cytosolic Ca(2+) concentration ([Ca(2+)](i)) was increased by PACAP, but not VIP, in a concentration range from 10(-12) to 10(-8) M via the PAC(1)-R in isolated single cells from the rat neural fold. This activation of the cells by PACAP was mimicked by agonists and inhibited by antagonists of the cAMP/PKA and PLC/PKC cascades. These data indicate that PACAP/PAC(1)-R is linked to [Ca(2+)](i) signaling via two G-protein-coupled protein kinase pathways and may thereby play an important role in early neurodevelopment.

A novel bacterial gene-finding system with improved accuracy in locating start codons

Although a number of bacterial gene-finding programs have been developed, there is still room for improvement especially in the area of correctly detecting translation start sites. We developed a novel bacterial gene-finding program named GeneHacker Plus. Like many others, it is based on a hidden Markov model (HMM) with duration. However, it is a 'local' model in the sense that the model starts from the translation control region and ends at the stop codon of a coding region. Multiple coding regions are identified as partial paths, like local alignments in the Smith-Waterman algorithm, regardless of how they overlap. Moreover, our semiautomatic procedure for constructing the model of the translation control region allows the inclusion of an additional conserved element as well as the ribosome-binding site. We confirmed that GeneHacker Plus is one of the most accurate programs in terms of both finding potential coding regions and precisely locating translation start sites. GeneHacker Plus is also equipped with an option where the results from database homology searches are directly embedded in the HMM. Although this option does not raise the overall predictability, labeled similarity information can be of practical use. GeneHacker Plus can be accessed freely at http://elmo.ims.u-tokyo.ac.jp/GH/.

Free radical-mediated tolbutamide desensitization of K+ATP channels in rat pancreatic beta-cells

To study the effects of hydroxyl radicals on the sensitivity of the ATP-sensitive K+ (K+ ATP) channel to tolbutamide, we used patch clamp and microfluorometric techniques in pancreatic beta-cells isolated from rats. cell-attached membrane patches, exposure of the cells to 0.3 mM H2O2 increased the probability of opening of K+ATP channels in the presence of 2.8 mM glucose. Tolbutamide dose-dependently inhibited the K+ATP channel with half-maximal inhibition (IC50) at 0.8 microM before and immediately after exposure to H2O2. After prolonged exposure (>20 min) to H2O2, the IC50 was increased to 15 microM. The presence of both ATP and ADP at concentrations ranging from 0.01 to 0.1 mM in the inside-out bath solution significantly enhanced the inhibition of the channels by 10 microM tolbutamide. Addition of 0.3 mM H2O2 induced a transient minute increase in the cytoplasmic Ca2+ concentration ([Ca2+]i) within 10 min, followed by a sustained pronounced increase in [Ca2]i. After more than 20 min of exposure of cells to 0.3mM H2O2, [Ca2]i was increased to above 2 microM. Treatment of the cytoplasmic face of inside-out membrane patches with 1 microM Ca2+ attenuated the tolbutamide-sensitivity of the K+ATP channel, but not the ATP-sensitivity of the channel. These findings indicate that H2O2 reduces tolbutamide sensitivity by inducing a sustained increase in [Ca2+]i.

Hormonal control of osmoregulation in the channel catfish Ictalurus punctatus

Prolactin (PRL) is an important hormone for freshwater adaptation in many teleost species. In some euryhaline fishes, growth hormone (GH) and cortisol are involved in seawater adaptation by stimulating ion extrusion. When channel catfish (Ictalurus punctatus) were transferred from fresh water to dilute seawater (300-400 mOsm), their plasma osmolality was always higher than the environmental salinity. In correlation with the increase in plasma osmolality, significant increases in plasma cortisol were observed. However, no effect of ovine GH or cortisol was seen in plasma osmolality or gill Na, K-ATPase activity when the hormones were given during the course of acclimation to dilute seawater. When catfish in fresh water were hypophysectomized, plasma osmolality was significantly decreased by 24 h, reaching a minimum level after 2 days. When they were transferred to dilute seawater, the plasma osmolality of the sham-operated fish was consistently higher than that of environmental water, whereas the osmolality of the hypophysectomized fish was equivalent to the environmental salinity. Ovine PRL restored the plasma osmolality of the hypophysectomized fish in fresh water to the level of sham-operated fish. Cortisol was also effective, but the effect was less pronounced than the effect of PRL. Injection of PRL in combination with cortisol resulted in a marked additive increase in plasma osmolality to a level even above that of the sham-operated fish. Ovine GH was without effect. These treatments in hypophysectomized fish transferred to dilute seawater produced essentially the same results as those in fish in fresh water. Plasma osmolality was also increased after PRL treatment of the intact fish in fresh water. There was a synergistic effect between PRL and cortisol in hypophysectomized fish in dilute seawater as well as in intact fish in fresh water. PRL did not stimulate cortisol secretion either in hypophysectomized fish or in intact fish. In the stenohaline catfish, both PRL and cortisol seem to be involved importantly in ion uptake from the environment not only in fresh water but also in brackish water.

Stimulation of non-specific immune functions in seawater-acclimated rainbow trout, Oncorhynchus mykiss, with reference to the role of growth hormone

The influence of acclimation to seawater (SW) and growth hormone (GH) administration on immune functions was examined in the rainbow trout (Oncorhynchus mykiss). After 3 days acclimation to dilute SW (12 parts per thousand, ppt), an increase in plasma lysozyme activity was observed compared to the fish kept in fresh water (FW). No change was seen in plasma immunoglobulin M (IgM) levels. When they were transferred from dilute SW to full-strength SW (29 ppt) after a single intra-peritoneal injection of ovine or salmon GH, plasma sodium levels of GH-treated fish were significantly lower than those of the control fish injected with Ringer's solution 24 h after the transfer. The plasma level of IgM was not influenced by GH injection in the fish kept in FW nor in those transferred to SW. The administration of GH increased plasma lysozyme activity in the fish in FW, but no further increase was seen after SW transfer. The production of superoxide anions in peripheral blood leucocytes was stimulated by GH in both FW and SW. These results suggest that GH is involved in the stimulation of the non-specific immune functions in SW-acclimated salmonids.

Its8, a fission yeast homolog of Mcd4 and Pig-n, is involved in GPI anchor synthesis and shares an essential function with calcineurin in cytokinesis

In fission yeast, calcineurin is required for cytokinesis and ion homeostasis; however, most of its physiological roles remain obscure. To identify genes that share an essential function with calcineurin, we screened for mutations that confer sensitivity to the calcineurin inhibitor FK506 and high temperature and isolated the mutant its8-1. its8(+) encodes a homolog of the budding yeast MCD4 and human Pig-n that are involved in glycosylphosphatidylinositol (GPI) anchor synthesis. Consistently, reduced inositol labeling of proteins suggested impaired GPI anchor synthesis in its8-1 mutants. The temperature upshift induced a further decrease in inositol labeling and caused dramatic increases in the frequency of septation in its8-1 mutants. BE49385A, an inhibitor of MCD4 and Pig-n, also increased the septation index of the wild-type cell. Osmotic stabilization suppressed these morphological defects, indicating that cell wall weakness caused by impaired GPI anchor synthesis resulted in abnormal cytokinesis. Furthermore, calcineurin-deleted cells exhibited hypersensitivity to BE49385A, and FK506 exacerbated the cytokinesis defects of the its8-1 mutant. Thus, calcineurin and Its8 may share an essential function in cytokinesis and cell viability through the regulation of cell wall integrity.

Functional significance of colocalization of PACAP and catecholamine in nerve terminals

Medullary neurons containing pituitary adenylate cyclase-activating polypeptide (PACAP) and noradrenalin (NA) project to the hypothalamus and they are involved in the regulation of arginine vasopressin (AVP) neurons. At the ultrastructural level, PACAP immunoreactivity was detected in the granular vesicles in catecholaminergic nerve terminals that made synaptic contact with AVP neurons. Both PACAP (at least 1 nM) and NA (at least 1 microM) induced large increases in the cytosolic Ca2+ concentration ([Ca2+]i) in isolated AVP cells. PACAP at 0.1 nM and NA at 0.1 microM had little effects, if any, on [Ca2+]i. However, when 0.1 nM PACAP and 0.1 microM NA were combined, they evoked large increase in [Ca2+]i in AVP neurons. An inhibitor of protein kinase A (PKA) completely inhibited the PACAP-induced increase in [Ca2+]i, but only partly inhibited the NA-induced increase in [Ca2+]i. In AVP cells that were prelabeled with quinacrine, PACAP and NA acted synergistically to induce a loss of quinacrine fluorescence, indicating secretion of neurosecretory granules in AVP neurons. The results suggest that PACAP and NA, coreleased from the same nerve terminals, act in synergy to evoke calcium signaling and secretion in AVP neurons, and that the synergism is mediated by the interaction between cAMP-PKA pathway an as yet unidentified factor "X" linked to L-type Ca2+ channels. The synergism between PACAP and NA may contribute to the regulation of AVP secretion under physiological conditions.

Intraperitoneal PACAP administration decreases blood glucose in GK rats, and in normal and high fat diet mice

PACAP is an islet peptide that serves as an endogenous amplifier of glucose induced insulin secretion. Furthermore, we has recently found that PACAP also potentiates insulin stimulated glucose uptake in adipocytes. Therefore, an antidiabetic action of PACAP is possible. In the present study, we examined the effect of PACAP treatment of the hyperglycemia in GK rats, an animal model of type 2 diabetes, and in high fat fed C47BL/6J mice, an animal model for glucose intolerance. GK rats housed with normal diet exhibited a normal level of blood glucose until three weeks old but significant hyperglycemia at eight weeks. When GK rats were treated with daily PACAP38 (i.p. injection, 6 pmol/kg) from age three weeks, development of hyperglycemia was prevented. In high fat fed mice, i.p. administration of PACAP27 for five (25 nmol/kg twice daily) reduced plasma glucose levels to 6.9 +/- 0.2 mmol/l compared to 8.1 +/- 0.2 mmol/l in saline injected animals (p < 0.001) without altering baseline insulin levels. We conclude that PACAP reduces circulating glucose in animal models of type 2 diabetes and glucose intolerance. The mechanism of this action needs to be established.

Insulinotropin PACAP potentiates insulin action. Stimulation of glucose uptake in 3T3-LI adipocytes

PAC1 receptor was expressed in the rat fat tissue and 3T3-L1 adipocytes. PACAP-38 (10 nM) significantly enhanced insulin induced 2-deoxyglucose uptake by 3T3-L1 adipocytes. GLP-1 has a similar effect. PACAP-38 further increased insulin stimulated phosphatidylinositol (PI) 3-kinase activity, but has not effect on tyrosine phosphorylation of insulin receptor beta-subunit or IRS-1. These results reveal that PACAP-38 enhances insulin induced glucose uptake, an effect probably mediated by PI 3-kinase. In conclusion, PACAP potentiates not only insulin secretion but also insulin action in adipocytes, thereby exhibiting antidiabetic actions at two important steps of glucose metabolism (Fig. 2).

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

A physical map of the human genome

The human genome is by far the largest genome to be sequenced, and its size and complexity present many challenges for sequence assembly. The International Human Genome Sequencing Consortium constructed a map of the whole genome to enable the selection of clones for sequencing and for the accurate assembly of the genome sequence. Here we report the construction of the whole-genome bacterial artificial chromosome (BAC) map and its integration with previous landmark maps and information from mapping efforts focused on specific chromosomal regions. We also describe the integration of sequence data with the map.

Production of biologically active recombinant bovine interferon-gamma by two different baculovirus gene expression systems using insect cells and silkworm larvae

The full-length bovine interferon-gamma (bIFN-gamma) cDNA, including the secretion signal peptide coding region was recloned into baculovirus transfer vectors pAcYM1 and pBm050. These vectors were co-transfected with Autographa californica nuclear polyhedrosis virus (AcNPV) or Bombyx mori nuclear polyhedrosis virus (BmNPV) DNA into Spodoptera frugiperda cells (SF21AE) and Bombyx mori cells (BmN), respectively. The recombinant viruses, named AcBIFN-gamma and BmBIFN-gamma, were then recovered. Recombinant bIFN-gamma (rbIFN-gamma) was accumulated in the culture fluid of AcBIFN-gamma-infected Trichoplusia ni cells and BmBIFN-gamma-infected silkworm larvae. These rbIFN-gamma forms were shown to be glycosylated 20 and 22 kDa proteins as confirmed by SDS-PAGE and tunicamycin treatment. These products were sensitive to cystein proteinase. Both rbIFN-gamma proteins, showed high-level biological activities by plaque reduction assay using vesicular stomatitis virus, and MHC class II antigen induction on bovine macrophage cells.

A new hypoglycemic agent, JTT-608, evokes protein kinase A-mediated Ca(2+) signaling in rat islet beta-cells: strict regulation by glucose, link to insulin release, and cooperation with glucagon-like peptide-1(7-36)amide and pituitary adenylate cyclase-activating polypeptide

A new nonsulfonylurea oral hypoglycemic agent, JTT-608, has been reported to stimulate insulin release at elevated, but not low, glucose concentrations and consequently not to induce hypoglycemia in rats. Accordingly, this drug is potentially a safer antidiabetic agent than sulfonylureas. To explore the mechanisms underlying this glucose-dependent insulinotropism, the present study investigated the effects of JTT-608 on cytosolic free Ca(2+) concentration ([Ca(2+)](i)) and protein kinase A (PKA) activity in rat islet beta-cells by microfluorometry using, respectively, fura-2 and a fluorescence PKA substrate, DR II. In the presence of glucose at normal and elevated concentrations (5.0-16.7 mM) JTT-608 (30-1000 microM) concentration dependently increased [Ca(2+)](i) in up to 88% of single beta-cells, whereas at lower glucose concentrations (2.8 and 4.2 mM) it had little effect. The [Ca(2+)](i) responses were inhibited under Ca(2+)-free conditions and by nitrendipine, an L-type Ca(2+) channel blocker. JTT-608 rapidly activated PKA and a PKA inhibitor, H89, inhibited [Ca(2+)](i) responses to JTT-608. JTT-608 also stimulated insulin release from rat islets in a glucose- and Ca(2+)-dependent manner. The glucose-unresponsive beta-cells, which failed to respond to 8.3 mM glucose with increases in [Ca(2+)](i), were frequently recruited to [Ca(2+)](i) increases by JTT-608. JTT-608 also induced oscillations of [Ca(2+)](i). Glucagon-like peptide-1(7-36)amide (GLP-1), pituitary adenylate cyclase-activating polypeptide (PACAP), and acetylcholine (ACh) enhanced the action of JTT-608 on [Ca(2+)](i). In conclusion, JTT-608 evokes PKA-mediated Ca(2+) influx and Ca(2+) signaling in rat islet beta-cells in a glucose-regulated manner, which may account for its glucose-dependent insulinotropism. JTT-608 and neurohormones may cooperatively activate islet beta-cells under physiological conditions.

PIP2 and ATP cooperatively prevent cytosolic Ca2+-induced modification of ATP-sensitive K+ channels in rat pancreatic beta-cells

The factors that influence functional coupling between the sulfonylurea receptor (SUR1) and Kir6.2 subunits of ATP-sensitive K+ (K+(ATP)) channels were studied in rat pancreatic beta-cells using patch clamp and microfluorometric techniques. Tolbutamide at 10 micromol/l inhibited K+(ATP) channels in association with occurrence of action currents, but further exposure of beta-cells to the drug for 30 min or longer resulted in reappearance of K+(ATP) channel events. Half-maximal inhibition concentration (IC50) for tolbutamide was 1.5 microl/mol in 2.8 mmol/l glucose, and it was increased to 13.3 micromol/l when the cellular metabolism was inhibited by 0.5 mmol/l 2,4-dinitrophenol (DNP) for 5 min. Tolbutamide at 10 micromol/l induced an increase in cytosolic Ca2+ concentration ([Ca2+]i), and its amplitude was markedly reduced following exposure to 0.5 mmol/l DNP or long-term (30 min) exposure to 10 micromol/l tolbutamide. This tolbutamide insensitivity, as assessed by the [Ca2+]i response, was not observed when the external Ca2+ was omitted during the long-term exposure to tolbutamide. In cell-attached membrane patches, the tolbutamide insensitivity was also produced by treatment of cells with 150 micromol/l diazoxide and 25 mmol/l KCl in the presence, but not absence, of 2 mmol/l Ca2+ in the external solution. When the cytoplasmic face of inside-out membrane patches was treated with higher Ca2+ concentrations (2 micromol/l), both ADP-evoked activation and tolbutamide-induced inhibition of K+ ATP channels were attenuated with retaining ATP-induced inhibition, indicating the modification of K+(ATP) channels. The Ca2+-induced channel modification was prevented partially by phosphatidylinositol 4,5-bisphosphate (PIP2) and completely by ATP and PIP2 together, but not by ATP alone. Treatment of the channel with cytochalasin D, a disrupter of F-actin, evoked channel modification similar to that induced by Ca2+. The modification was prevented completely by phalloidin, a stabilizer of F-actin. In conclusion, long-term exposure to tolbutamide or metabolic inhibition causes modification of K+ ATP channels via mechanisms involving Ca2+-dependent reaction. The modification, which may reflect functional disconnection between SUR1 and Kir6.2, is prevented by ATP and PIP2, which may act cooperatively to stabilize membrane cytoskeletons (F-actin structures).

Ca2+ oscillations in response to methamphetamine in dopamine neurons of the ventral tegmental area in rats subchronically treated with this drug

Mesolimbic dopamine neurons in the ventral tegmental area (VTA), which project to the nucleus accumbens and prefrontal cortex, play an important role in the regulation of emotion, rewarding, and cognition. The dopamine neurons in the VTA have also been implicated in schizophrenia and drug abuse. Methamphetamine (METH) can induce a schizophrenia-like psychosis. Thus, the VTA is a likely effector site for the action of METH. However, effects of METH on the mesolimbic dopamine neurons are largely unknown. We treated adult SD rats with METH (5 mg/kg/day) or saline for 7 days, isolated single VTA neurons from these treated rats, and monitored the neuronal activities by measuring cytosolic Ca2+ concentration ([Ca2+]i), which was followed by immunocytochemical identification of dopamine neurons. Acute administration of METH under superfusion conditions concentration-dependently increased [Ca2+]i in VTA dopamine neurons isolated from METH- and saline-treated rats. Furthermore, acutely administered METH induced oscillations of [Ca2+]i only in the dopamine neurons of the METH-treated group. The METH-induced [Ca2+]i oscillations were inhibited by Ca2+-free conditions and by Ca2+ channel blockers. In conclusion, subchronic METH treatment sensitizes VTA dopamine neurons to this drug, resulting in induction of [Ca2+]i oscillations. This sensitization of VTA dopamine neurons may account, at least in part, for the psycho-stimulant effects of METH, such as the dependence on and sensitization to METH.

Orexin-induced hyperlocomotion and stereotypy are mediated by the dopaminergic system

We demonstrated involvement of the ventral tegmental area (VTA) dopaminergic system in orexin-induced hyperlocomotion and stereotypy in rats. In double-label immunohistochemical study of rat brain, we found that tyrosine hydroxylase (TH)-immunoreactive cells in the VTA received innervation from orexin immunoreactive-fibers. Orexin-A induced an increase in [Ca(2+)](i) in isolated A10 dopamine neurons in a dose-dependent manner. In behavioral studies, we found that orexin-A induced hyperlocomotion, stereotypy and grooming behavior when administered centrally in rats, and these effects were abolished by dopamine D(2) (haloperidol and sulpiride) or D(1) (SCH23390) antagonists. These results suggest that the orexin-induced hyperlocomotion, stereotypy and grooming behavior are mediated by the dopaminergic system and this pathway might be involved in orexin-induced emotional responses.

Intramyocardial influences on blood flow distributions in the myocardial wall

Flow velocity wave forms of coronary arterial inflow and venous outflow of myocardium are influenced by cardiac contraction and relaxation: arterial flow is exclusively diastolic; venous outflow is systolic. We first discuss the intramyocardial microvascular flow dynamics, then present some results of visualization of transmural microvessels by our needle-probe charge coupled device (CCD) microscope, along with an interpretation of the arteriolar and venular hemodynamics through a cardiac cycle. After describing a hierarchical system of coronary microvessels (small artery, arteriole, and capillary), we emphasize the importance of spatial heterogeneity of blood supply to myocardium with reference to a minimal vascular control unit (approximately 400 microm). An understanding of mechanoenergetic interaction is fundamentally important to an understanding of intramyocardial coronary circulation, and the Physiome Project will provide powerful tools for understanding the integrated role of the intramyocardial microcirculation system.