Biomedical subjects

Y Tokumitsu

Publications and source records attributed to Y Tokumitsu.

At least 19 recordsLinked to original sources

PubMed2001

Calcitonin induces IL-6 production via both PKA and PKC pathways in the pituitary folliculo-stellate cell line.

It has been demonstrated that calcitonin-binding sites are present in a variety of tissue types, including in the pituitary gland. Interleukin-6 (IL-6) is also produced in the pituitary and it regulates the secretion of various hormones. In this study, we examined the expression of the calcitonin receptor and the mechanism of IL-6 production induced by calcitonin in the pituitary folliculo-stellate cell line (TtT/GF). The mRNA of calcitonin receptor subtype C1a, but not that of C1b, was detected by RT-PCR in TtT/GF cells and in the normal mouse pituitary. Calcitonin increased cAMP accumulation and IL-6 production in a concentration-dependent manner in TtT/GF cells. As calcitonin activates the PKA and PKC pathways, we investigated the contributions of PKA and PKC to IL-6 production. IL-6 production was only slightly increased by either 8-bromo-cAMP (1 mM) or phorbol 12-myristate 13-acetate (100 nM) alone. However, IL-6 was synergistically induced in the presence of both 8-bromo-cAMP (1 mM) and phorbol 12myristate 13-acetate (100 nM). Furthermore, calcitonin-induced IL-6 production was completely suppressed by H-89 (PKA inhibitor) or GF109203X (PKC inhibitor), indicating that the activation of both PKA and PKC is necessary for calcitonin-induced IL-6 production. On the other hand, pertussis toxin (G(i)/G(o) signaling inhibitor) treatment achieved an approximately 9-fold increase in calcitonin-induced IL-6 production. These results show that calcitonin-stimulated IL-6 production is mediated via both PKA- and PKC-signaling pathways, whereas calcitonin also suppresses IL-6 production by activating G(i)/G(o) proteins in folliculo-stellate cells.

Animals↗

PubMed2000

Suppression of malignant growth potentials of v-Src-transformed human gallbladder epithelial cells by adenovirus-mediated dominant negative H-Ras.

Although Src transformation of NIH3T3 mouse fibroblasts has been shown to be dependent on Ras function, the signaling mechanism whereby Src induces malignant transformation of human epithelial cells still remains unclear. In the present study, we analyzed the functional role of Ras, which acts downstream of Src in intracellular signaling, in the acquisition of fully neoplastic potentials by v-Src-transformed human gallbladder epithelial cells (HAG/src3-1) by infecting these cells with replication-defective adenovirus vector expressing dominant negative H-Ras (AdCARasY57). High efficiency of gene transduction was demonstrated with the adenovirus vector containing beta-gal gene insert (AdCALacZ). On infection with AdCARasY57, the activity of mitogen-activated protein (MAP) kinase, a major downstream event triggered by Ras, was markedly inhibited over 7 days, indicating that the inhibition of Ras function by AdCARasY57 remains active during this period. AdCARasY57 did not inhibit the monolayer growth of HAG-1 cells transfected with activated H-ras, but inhibited the HAG/src3-1 cells by 30%, as compared with cells infected with AdCALacZ as a control. This growth inhibition by AdCARasY57 was strengthened nearly twofold on surfaces coated with an antiadhesive polymer (poly 2-hydroxyethylmethacrylate) that can quantitate anchorage-independent growth, and was much more pronounced up to 95% when assayed in soft agar. The HAG/src3-1 cells transfected with beta-gal gene produced tumors in nude mice within 4 weeks after implantation, whereas cells infected with AdCARasY57 failed to form tumors during this period. These findings show that Ras function is essential for v-Src-induced anchorage-independent growth in vitro as well as tumorigenesis in vivo, and that mitogenic activity driven by v-Src is not solely dependent on MAP kinase pathway. Because anchorage-independent growth correlates with tumor growth in vivo as well as metastatic potential, targeting Ras would be potentially useful for the treatment of human tumors with elevated Src tyrosine kinase activity.

Adenoviridae↗

PubMed1999

Translocation of G-protein beta3 subunit from the cytosol pool to the membrane pool by beta1-adrenergic receptor stimulation in perfused rat hearts.

To elucidate the intracellular function and localization of the heterotrimeric G-protein beta3 subunit (Gbeta3) in the heart, we studied the effects of subtype-specific beta-adrenergic receptor (beta-AR) stimulation on Gbeta3 localization using isoform-specific antibodies. The amount of Gbeta3 in the cytosol dramatically decreased in hearts perfused with isoproterenol (ISO) alone or ISO with ICI 118551, a beta2-AR antagonist. Propranolol or CGP 20712A, a beta1-AR antagonist, blocked the ISO-induced decrease in the Gbeta3 content of the cytosol. In contrast, Gbeta3 content of the membrane fraction significantly increased in hearts perfused with ISO alone or ISO with ICI 118551. We conclude that stimulation of the beta1-AR induces isoform-specific translocation of Gbeta3 from the cytosol to the membrane fraction in rat hearts.

Animals↗

PubMed1999

Troglitazone suppresses cell growth of myeloid leukemia cell lines by induction of p21WAF1/CIP1 cyclin-dependent kinase inhibitor.

In a human eosinophilic leukemia cell line, EoL-1, cell proliferation was suppressed by 2-day treatment with troglitazone. EoL-1 cells treated with troglitazone were arrested and maintained in the G0/G1 phase in the cell cycle. This suppression correlated with the up-regulation of mRNA for p21WAF1/CIP1 cyclin-dependent kinase (Cdk) inhibitor. The inhibitory effects of troglitazone on cell proliferation and expression of p21 mRNA were observed in a human myelomonocytic cell line, U937, and a human myelomonoblastic cell line, KPB-M15. In addition, in EoL-1 cells, p21 protein was induced by troglitazone treatment and the induction was inhibited by protein synthesis inhibitor, cycloheximide. These data suggest that troglitazone inhibits cell proliferation in myeloid leukemia cell lines at least in part by induction of p21 Cdk inhibitor.

Antineoplastic Agents↗

PubMed1999

Inositol-1,4,5-trisphosphate accumulation induced by urinary pheromones in female rat vomeronasal epithelium.

The mechanisms involved in pheromone-induced responses in the vomeronasal neurons, especially in mammals, are still unclear. In the present study, we examined the effects of rat urine samples containing various types of pheromones regulating gonadal functions on the accumulation of cAMP and inositol 1,4,5-trisphosphate (IP3) in a vomeronasal membrane preparation from the female Wistar rat. Stimulation of the preparation with forskolin induced cAMP accumulation, but stimulation with urine samples excreted from the male Wistar rat, the female Wistar rat, and the male Donryu rat did not change cAMP levels. These results were consistent with the electrophysiological results showing that dialysis of a high concentration of cAMP into the vomeronasal neuron does not induce currents. Stimulation with the three urine samples induced the accumulation of IP3 in the membrane preparation. These results are consistent with previous electrophysiological results [K. Inamura, M. Kashiwayanagi, K. Kurihara, Inositol-1,4,5-trisphosphate induces responses in receptor neurons in rat vomeronasal sensory slices, Chem. Senses 22 (1997) 93-103; K. Inamura, M. Kashiwayanagi, K. Kurihara, Blockage of urinary responses by inhibitors for IP3-mediated pathway in rat vomeronasal sensory neurons, Neurosci. Lett. 233 (1997) 129-132]. After the treatment with Pertussis toxin (PTX), the male Wistar urine did not induce IP3 accumulation significantly. Application of the male Wistar urine decreased ADP-ribosylation of Gi with PTX, while that of the male Donryu urine decreased ADP-ribosylation of Go. Thus, the present results support a mechanism by which the responses of the rat vomeronasal neurons to urinary pheromones are mediated by IP3, Gi and/or Go.

Animals↗

PubMed1999

Pertussis toxin-sensitive and insensitive intracellular signalling pathways in undifferentiated 3T3-L1 cells stimulated by insulin converge with phosphatidylinositol 3-kinase upstream of the Ras mitogen-activated protein kinase cascade.

We have previously reported that pertussis toxin (PTX)-sensitive GTP binding protein (G-protein) and phosphatidylinositol 3-kinase (PI 3-K) are involved in adipocyte differentiation of 3T3-L1 cells induced by insulin/dexamethasone/methylisobutyl xanthine. The aim of this study was to examine the effect of PTX on the tyrosine kinase cascade stimulated by insulin acting through insulin-like growth factor-I (IGF-I) receptors in undifferentiated 3T3-L1 cells. A high level of mitogen-activated protein kinase (MAPK) activation was sustained for up to 4 h after insulin treatment, and mobility shifted and tyrosine phosphorylated MAPK was also detected. MAPK kinase activity measured by the incorporation of 32P into kinase-negative recombinant MAPK was enhanced by insulin treatment. We previously discovered that insulin activates Ras and that this is mediated by wortmannin-sensitive PI 3-K. Tyrosine-phosphorylation of IRS-1 and Shc also occurred in response to insulin. Subsequently, we investigated the effects of PTX on the activation of these proteins by insulin. Interestingly, treating 3T3-L1 cells with PTX attenuates the activation by insulin of both the Ras-MAPK cascade and PI 3-K. In contrast, neither tyrosine-phosphorylation of IRS-1 and Shc nor the interaction between IRS-1 and PI 3-K is sensitive to PTX. However, activation of the Ras-MAPK cascade and tyrosine-phosphorylation of Shc by epidermal growth factor are insensitive to PTX. These results indicate that there is another pathway which regulates PI 3-K and Ras-MAPK, independent of the pathway mediated by IGF-I receptor kinase. These findings suggest that in 3T3-L1 fibroblasts, PTX-sensitive G-proteins cross-talk with the Ras-MAPK pathway via PI 3-K by insulin acting via IGF-I receptors.

3T3 Cells↗

PubMed1999

Prognostic significance of polo-like kinase expression in esophageal carcinoma.

PLK (polo-like kinase), which belongs to a family of serine/threonine kinases and represents the human counterpart of structurally related protein kinases, polo of Drosophila melanogaster and CDC5 of Saccharomyces cerevisiae, may be implicated in spindle formation and chromosome segregation during mitosis. There are, however, few reports on the significance of PLK gene expression in human carcinomas. In order to evaluate its clinical significance, we examined the expression of the PLK mRNA in 49 esophageal and 75 gastric carcinomas, using reverse transcription-polymerase chain reaction analysis. In esophageal carcinomas, PLK overexpression was detected in 47 carcinomas (97%) when compared to the corresponding normal tissues. It is noteworthy that the patients with high-grade PLK overexpression represented a significantly poorer prognosis group than those with low-grade PLK overexpression (3-year survival rate: 54.9% vs 24.8%, p<0.05). A multivariate analysis demonstrated that the PLK mRNA expression status was an independent prognostic factor for patients with esophageal carcinoma. On the other hand, 55 gastric carcinomas (73%) were revealed to overexpress PLK mRNA, but the expression status showed no correlation with prognosis. This study demonstrated that the PLK overexpression was frequently observed in esophageal and gastric carcinomas, and appeared to be an independent prognostic factor for patients with esophageal carcinoma.

Adenocarcinoma↗

PubMed1998

Downregulation of mRNA expression of Edg-3, a putative sphingosine 1-phosphate receptor coupled to Ca2+ signaling, during differentiation of HL-60 leukemia cells.

We measured the mRNA expression of the recently identified putative sphingosine 1-phosphate (S1P) receptors, i.e., Edg-1, AGR16/H218, and Edg-3, in HL-60 leukemia cells. Of these putative receptors, Edg-3 mRNA was abundantly expressed in undifferentiated HL-60 cells. Further, its mRNA expression was markedly downregulated by inducers of cell differentiation such as dibutyryl cAMP, retinoic acid, and 1alpha, 25-dihydroxyvitamin D3. The reduction of mRNA expression was associated with the attenuation of an S1P-induced increase in cytoplasmic free Ca2+ concentration. Thus, Edg-3, whose mRNA expression is downregulated during cell differentiation, may be responsible for the S1P-induced Ca2+ response in HL-60 leukemia cells.

3T3 Cells↗

PubMed1998

Stimulatory and inhibitory actions of lysophosphatidylcholine, depending on its fatty acid residue, on the phospholipase C/Ca2+ system in HL-60 leukaemia cells.

We examined the mechanism of action of lysophosphatidylcholine (LPC), which is suggested to be involved in the pathogenesis of atherosclerosis and inflammatory disorders, in HL-60 leukaemia cells. Extracellular 1-palmitoyl LPC increased the intracellular Ca2+ concentration in association with production of inositol phosphate. These actions of LPC were markedly inhibited by treatment of the cells with pertussis toxin and U73122, a phospholipase C inhibitor. The lipid-induced stimulation of the phospholipase C/Ca2+ system was also attenuated in the dibutyryl cAMP-induced differentiated (neutrophil-like) cells, in which phospholipase C activation induced by NaF or formyl-Met-Leu-Phe was enhanced. In contrast with the stimulatory action of 1-palmitoyl LPC, 1-stearoyl LPC was inhibitory for the phospholipase C/Ca2+ system stimulated by NaF as well as by 1-palmitoyl LPC or other Ca2+-mobilizing agonists. In a cell-free system, only an inhibitory effect on phospholipase C activity was observed even by 1-palmitoyl LPC; 1-stearoyl LPC was more inhibitive than 1-palmitoyl LPC. Taken together, these results suggest that atherogenic and inflammatory LPC exerts both stimulatory and inhibitory actions on the phospholipase C/Ca2+ system depending on the species of fatty acid residue of the lipid; the stimulatory effect is possibly mediated through G-protein-coupled receptors; the inhibitory effect might be caused by dysfunction of the components involved in the enzyme system owing to the amphiphilic nature of the lipid. 1-Palmitoyl LPC prefers the former receptor stimulation at least in intact cells, but 1-stearoyl LPC preferentially exerts the latter inhibitory action.

Bucladesine↗

PubMed1998

Lacustrine sockeye salmon return straight to their natal area from open water using both visual and olfactory cues.

Mechanisms of the amazing ability of salmon to migrate a long distance from open water to natal streams for spawning are still unknown. Lacustrine sockeye salmon (Oncorhynchus nerka) in Lake Toya offers an excellent model system for studying the orientation mechanism in open water, because mature fish return to the natal area with a high degree of accuracy. First we examined the percentage of fish returning to the natal area after they were released 7 km south of the natal area. Forty percent of control male mature fish and 25% of the fish blinded by injection of a mixture of carbon toner and corn oil into the eyeball were captured in the natal area within 5 days. Forty-four percent of fish with brass rings (control) and 31% of fish with NdFe magnetic rings which interfere with the magnetic cue were captured in the natal area within 3 days. These experiments suggested that, although the number of blinded fish captured in the natal area was less than that of the controls, the difference was not statistically significant. In the fish captured in the natal area within 3 or 5 days, fish which found the natal area using their olfactory cue after random swimming for a long time and returned to that area may be included. Hence we tracked fish telemetrically using an ultrasonic tracking system, and found that mature males released at a long distance (3.6 or 6.8 km) from the natal area swam straight to the vicinity of the natal area. Interference of the magnetic cue by the attachment of a magnetic ring did not affect their direct return. Blockage of the visual cue caused them to move randomly. These data suggest that lacustrine sockeye salmon return straight to the vicinity of the natal area using their visual cue and finally reach the exact homing point using their olfactory cue.

Animals↗

PubMed1998

Hemophagocytic syndrome associated with fulminant ulcerative colitis and presumed acute pancreatitis.

We herein report a case of hemophagocytic syndrome that developed in a 25-yr-old man with fulminant ulcerative colitis and presumed acute pancreatitis. Physical examination on admission showed a chronically ill, delirious patient with an upper abdominal mass. Peripheral blood showed progressive pancytopenia and bone marrow aspirate smears revealed hypocellular bone marrow with an increase of histiocytes showing prominent hemophagocytosis. Plain abdominal radiography revealed toxic megacolon. Both ultrasound and computed tomography showed the enlargement of the pancreas, thus indicating presumed acute pancreatitis. No apparent neoplasms or viral or bacterial infections, which are normally reported to be the cause of hemophagocytic syndrome, were detected. The patient was successfully treated with high doses of prednisolone and gamma-globulin.

Acute Disease↗

PubMed1998

Comparison of atypical beta3-adrenoceptor agonists with their respective metabolic activities in rat white adipocytes.

The metabolic activities of four types of beta3-adrenoceptor (AR) agonists, BRL35135A, BRL28410, ICI215001 and CL316243, were compared with those of other beta1- and beta2-AR agonists in rat white adipocytes. All the beta3-AR agonists caused cAMP formation, free fatty acid release and 2-deoxyglucose uptake; the maximum activity levels were similar except for ICI215001, which was lower. However, the magnitude of potency and selectivity of these agonists differed. The most potent and selective beta3-agonist was CL316243. Metabolic activities and Northern blotting showed that there were three beta-AR subtypes that were coupled to adenylyl cyclase and contributed to the induction of lipolysis and glucose uptake. The rank order of the amounts of beta-AR subtypes was beta3 >>beta1> beta2. However, the physiological functions of beta-AR subtypes were essentially similar in rat white adipocytes. On the other hand, cAMP accumulation and Northern blotting showed that human adipocytes predominantly contained beta2-AR, with far lower levels of beta1- and beta3-ARs. These findings suggested that the beta3-AR plays an important role in energy metabolism and thermogenesis in which cross talk exists between beta1- and beta3-ARs in rat adipocytes, while beta2-AR is the most important for the lipolysis regulation in human subcutaneous adipocytes.

Adenylyl Cyclases↗

PubMed1997

Suppression of insulin-stimulated phosphatidylinositol 3-kinase activity by the beta3-adrenoceptor agonist CL316243 in rat adipocytes.

Insulin increased 2-deoxyglucose (2-DG) uptake via the translocation of glucose transporter (GLUT) 4 to the plasma membrane fraction in rat adipocytes. The stimulatory actions of insulin were accompanied by both an increase in the immunoreactive p85 subunit of phosphatidylinositol (PI) 3-kinase in the plasma membrane fractions and PI 3-kinase activation by tyrosine phosphorylation of the p85 subunit. The beta3-adrenoceptor agonist CL316243 (CL) suppressed all the insulin actions in adenosine deaminase (ADA)-treated cells, but was without effect in non-ADA-treated cells. The inhibitory effects of CL on GLUT 4 translocation and PI 3-kinase activation were abolished by the addition of N6-phenylisopropyl adenosine. Cholera toxin treatment, which markedly increased intracellular cAMP levels, suppressed increases in the levels of GLUT 4 and PI 3-kinase in the plasma membrane fractions in response to insulin. In addition, dibutyryl (Bt2) cAMP also impaired the activation of PI 3-kinase by insulin. These results indicated that CL suppressed insulin-stimulated glucose transport under conditions where cAMP levels were markedly increased (approximately 12-fold). The inhibitory actions of PI 3-kinase activation by insulin were exerted even when cAMP, 8-bromo-cAMP, or Bt2 cAMP was added to immunoprecipitates of the p85 subunit of PI 3-kinase, after treating the cells with insulin. These results suggest that CL suppressed insulin-stimulated PI 3-kinase activity via a cAMP-dependent mechanism, at least in part, direct cAMP action in ADA-treated adipocytes, by which PI 3-kinase activation was inhibited, resulting in the decrease in GLUT 4 translocation and subsequent 2-DG uptake in response to insulin.

Adenosine Deaminase↗

PubMed1997

Protein kinase A-dependent IL-6 production induced by calcitonin in human glioblastoma A172 cells.

In human glioblastoma A172 cells, interleukin-6 (IL-6) production was induced by interleukin-1 beta (IL-1 beta) and dibutyryl cyclic AMP. These cells have been shown to induce IL-6 production via a cAMP-protein kinase A system. Since calcitonin (CT) and calcitonin gene-related peptide (CGRP) are known to increase cAMP accumulation in murine and rat astrocytes, we examined whether these neuropeptides induced IL-6 production in A172 cells. Human CT and human CGRP increased IL-6 production and cAMP accumulation in a dose-dependent manner. A specific protein kinase A inhibitor, H-89, inhibited both CT- and CGRP-induced IL-6 production. CT and CGRP have been shown to cross-react with each other. To exclude the possibility of this cross-reactivity, we studied the additive effects of CT and CGRP and the inhibitory effects of specific inhibitors. When 100 nM CT was added, cAMP accumulation stimulated by 10 nM CGRP (the maximal dose) was increased. CGRP (8-37), a specific CGRP receptor inhibitor, inhibited cAMP accumulation and IL-6 production induced by CGRP, but did not inhibit these effects when they were induced by CT. Salmon CT (8-32), a specific inhibitor of the CT receptor, inhibited cAMP accumulation induced by CT, but did not inhibit the effect induced by CGRP. These results demonstrated that CT can induce IL-6 production via cAMP accumulation and the effects of CT are mediated via its own receptors.

Calcitonin↗

PubMed1997

Ki-67, p53, and Bcl-2 expression of serrated adenomas of the colon.

To investigate epithelial cell proliferation and oncoprotein expression of the serrated adenoma, a term that has been used synonymously with mixed hyperplastic and adenomatous polyp, immunohistochemical staining using polyclonal antibodies against Ki-67 and p53, and a Bcl-2 monoclonal antibody, was performed and the results compared with those in hyperplastic polyps and tubular adenomas. A total of 20 serrated adenomas all characterized by a serrated glandular pattern, contained immature goblet cells, upper crypt zone mitotic figures, and a few nucleoli within the epithelial cells. Twenty hyperplastic polyps and 20 tubular adenomas (all with low-grade dysplasia) were examined, and lesions that contained separate areas of hyperplastic and adenomatous glands were excluded. The Ki-67-positive rate in the middle zone of the crypts in serrated adenomas was significantly higher than in hyperplastic polyps but lower than in tubular adenomas; a similar tendency was also noted for the upper zone. Both serrated adenomas and hyperplastic polyps demonstrated Bcl-2-positive reactivity that was essentially limited to the lower crypt zone, while in contrast, involvement in tubular adenomas often extended to the middle zone. No p53 overexpression was found in any category. These results suggest that serrated adenomas may be committed to independent growth.

Adenoma↗

PubMed1996

Adenylyl cyclase activity in turtle vomeronasal and olfactory epithelium.

Many vertebrates have two olfactory systems such as the main olfactory organ and the vomeronasal organ. To compare the transduction mechanism in both systems, we measured adenylyl cyclase activity in turtle vomeronasal and olfactory epithelium preparations. Whereas forskolin and GTP induced cAMP accumulation in vomeronasal preparations, common odorants, which induced cAMP accumulation in olfactory preparations and electrophysiological responses in vomeronasal organs, did not induce cAMP accumulation in vomeronasal preparations. The present results suggest that the cAMP-mediated transduction pathway in the vomeronasal organ is not involved in transduction for common odorants and probably plays a role in perception of specific chemosignals.

Adenylyl Cyclases↗

PubMed1996

Dominance of the 'nondominant' hemisphere in depression.

We examined 36 patients with major depression diagnosed by DSM-III-R to find and qualify disturbances in brain oxygenation and hemodynamics during a psychological task. A group of 36 age- and sex-matched healthy volunteers were monitored as controls. Multichannel near-IR spectrophotometry (NIRS) was used to observe real-time alterations in the oxygenation in corresponding areas of the hemispheres at the forehead during the mirror drawing task (MDT). Nearly half of the patients (12 of 24 males and 4 of 12 females) showed a 'nondominant hemisphere response pattern', which was never observed in normal volunteers during the MDT. The other half of the patients showed a 'bilateral response pattern'. There was no 'dominant hemisphere response pattern', the pattern observed in most normal males. When re-examined after recovery from depression, the response pattern of the two patients who had shown the 'nondominant hemisphere response pattern' during the course of the illness had changed to the 'bilateral response pattern'. The response pattern of the three patients with refractory depression who first showed the 'bilateral response pattern' changed to the 'nondominant response pattern' after several months. The nominally 'nondominant' hemisphere may become dominant during the course of depression.

Adult↗

PubMed1996

Long-term neuroleptic treatments counteract dopamine D2 agonist inhibition of adenylate cyclase but do not affect pertussis toxin ADP-ribosylation in the rat brain.

We have investigated the response of adenylate cyclase to GTP and to dopamine (DA) in striatal membranes of rats treated for 3 weeks with chlorpromazine or haloperidol, and further measured the level of Gi (an inhibitory GTP-binding protein) or Go (a similar GTP-binding protein of unknown function) in 3 areas (cerebral cortex, striatum and hippocampus) utilizing pertussis toxin-catalyzed ADP ribosylation. In saline-treated control membranes, GTP exerted a biphasic effect on basal and DA-stimulated enzyme activity--peak levels of stimulation by DA plus GTP were observed at 1 microM GTP. Conversely, dopaminergic inhibitory effects at 10-100 microM GTP were completely attenuated in chlorpromazine or haloperidol-treated membranes. D2 inhibition of adenylate cyclase by the selective D2 agonist PPHT was also attenuated due to these neuroleptic treatments, while an increase in D2 receptor binding was observed. The pertussis toxin ADP-ribosylation of G-proteins (Gi/Go) did not differ significantly in any area. This indicates that long-term neuroleptic treatments increased D2 receptor binding, but attenuated D2 inhibition of adenylate cyclase, and exercised no influence on pertussis toxin ADP-ribosylation.

Adenosine Diphosphate Ribose↗