Anticancer Effects of Spiperone in C57BL/6 Mice with Emphysema and Lung Carcinoma.

The antitumor and antimetastatic activity of dopamine D2 receptor antagonists spiperone was studied in C57BL/6 mice in a model of combined pathology (emphysema and lung cancer). Emphysema was induced by administration of LPS and cigarette smoke extract. Lung cancer was induced by injection of Lewis lung carcinoma cells into the lung. It has been shown that under conditions of combined lung pathology, spiperone prevents inflammatory infiltration and emphysematous expansion of the lungs and reduces the size of the primary tumor node, the number of metastases, and the area of the lungs affected by metastases. Spiperone reduces the number of cancer stem cells (CSCs) in the lungs and blood of mice with combined pathology. CSCs isolated from the lungs and blood of mice with combined pathology treated with spiperone had a significantly lower potential to form a tumorosphere in vitro than CSCs from untreated mice with emphysema and lung carcinoma. Thus, blockade of dopamine D2 receptors is a promising approach for correcting combined lung pathology and can be used in the development of a method for treating lung cancer in patients with emphysema.

Micellar Hyaluronidase and Spiperone as a Potential Treatment for Pulmonary Fibrosis.

Concentration of hyaluronic acid (HA) in the lungs increases in idiopathic pulmonary fibrosis (IPF). HA is involved in the organization of fibrin, fibronectin, and collagen. HA has been proposed to be a biomarker of fibrosis and a potential target for antifibrotic therapy. Hyaluronidase (HD) breaks down HA into fragments, but is a subject of rapid hydrolysis. A conjugate of poloxamer hyaluronidase (pHD) was prepared using protein immobilization with ionizing radiation. In a model of bleomycin-induced pulmonary fibrosis, pHD decreased the level of tissue IL-1ß and TGF-ß, prevented the infiltration of the lung parenchyma by CD16+ cells, and reduced perivascular and peribronchial inflammation. Simultaneously, a decrease in the concentrations of HA, hydroxyproline, collagen 1, total soluble collagen, and the area of connective tissue in the lungs was observed. The effects of pHD were significantly stronger compared to native HD which can be attributed to the higher stability of pHD. Additional spiperone administration increased the anti-inflammatory and antifibrotic effects of pHD and accelerated the regeneration of the damaged lung. The potentiating effects of spiperone can be explained by the disruption of the dopamine-induced mobilization and migration of fibroblast progenitor cells into the lungs and differentiation of lung mesenchymal stem cells (MSC) into cells of stromal lines. Thus, a combination of pHD and spiperone may represent a promising approach for the treatment of IPF and lung regeneration.

Blockade of Dopamine D2 Receptors as a Novel Approach to Stimulation of Notch1+ Endothelial Progenitor Cells and Angiogenesis in C57BL/6 Mice with Pulmonary Emphysema Induced by Proteases and Deficiency of α1-Antitrypsin.

We studied the effects of spiperone, a selective blocker of dopamine D2 receptors, on the model of pulmonary emphysema provoked by administration of elastase and D-galactosamine hydrochloride to female C57BL/6 mice and characterized by activation of proteases in the lungs and systemic deficiency of its inhibitor α1-antitrypsin. In this model, spiperone prevented the development of inflammatory reaction and reduced the area of emphysematous expanded alveolar tissue. The expression of angiogenic marker CD31 in the lungs increased under these conditions. Regeneration of the damaged microvascular bed under the action of spiperone resulted from recruiting of Notch1+ endothelial progenitor cells (CD45-CD31+CD34+) into the lungs and blockade of the inhibitory effect of dopamine on phosphorylation of VEGF-2 receptors in endothelial cells of different maturity. In addition, spiperone produced a protective effect on hepatocytes and restored the production and secretion of α1-antitrypsin by these cells.

Distinct Dopamine D2 Receptor Antagonists Differentially Impact D2 Receptor Oligomerization.

Dopamine D2 receptors (D2R) are known to form transient homodimer complexes, of which the increased formation has already been associated with development of schizophrenia. Pharmacological targeting and modulation of the equilibrium of these receptor homodimers might lead to a better understanding of the critical role played by these complexes in physiological and pathological conditions. Whereas agonist addition has shown to prolong the D2R dimer lifetime and increase the level of dimer formation, the possible influence of D2R antagonists on dimerization has remained rather unexplored. Here, using a live-cell reporter assay based on the functional complementation of a split Nanoluciferase, a panel of six D2R antagonists were screened for their ability to modulate the level of D2LR dimer formation. Incubation with the D2R antagonist spiperone decreased the level of D2LR dimer formation significantly by 40-60% in real-time and after long-term (≥16 h) incubations. The fact that dimer formation of the well-studied A2a-D2LR dimer was not altered following incubation with spiperone supports the specificity of this observation. Other D2R antagonists, such as clozapine, risperidone, and droperidol did not significantly evoke this dissociation event. Furthermore, molecular modeling reveals that spiperone presents specific Tyr1995.48 and Phe3906.52 conformations, compared to clozapine, which may determine D2R homodimerization.

Spiroperidol, but not eticlopride or aripiprazole, produces gradual increases in descent latencies in the bar test in rats.

Rats repeatedly exposed to the bar test following injections with a dopamine D2-like receptor antagonist such as haloperidol show increased descent latencies, suggesting that contextual stimuli may lose their ability to elicit approach and other responses. Here, we showed that rats took progressively longer to initiate descent from a horizontal bar across sessions following daily intraperitoneal treatment (paired group) with the D2-like receptor antagonist, spiroperidol (0.125 and 0.25 mg/kg), but not in the control group that received 0.25 mg/kg in their home cage and testing following saline. When both groups were tested following an injection of spiroperidol or following saline, a sensitized and a conditioned increase in descent latency, respectively, were observed in the paired but not in the unpaired group. No evidence of sensitization or conditioning was found with the substituted benzamide compound, eticlopride (0.15-0.5 mg/kg), or the D2-like receptor partial agonist, aripiprazole (0.25-0.5 mg/kg). The different effects of these agents on learning may be related to different region-specific affinities for dopamine receptors or differences in receptor dissociation profiles. We suggest that the behavioural changes observed in spiroperidol-treated rats may reflect inverse incentive learning.

Dopamine D1 receptor modulation of calcium channel currents in horizontal cells of mouse retina.

Horizontal cells form the first laterally interacting network of inhibitory interneurons in the retina. Dopamine released onto horizontal cells under photic and circadian control modulates horizontal cell function. Using isolated, identified horizontal cells from a connexin-57-iCre × ROSA26-tdTomato transgenic mouse line, we investigated dopaminergic modulation of calcium channel currents (ICa) with whole cell patch-clamp techniques. Dopamine (10 µM) blocked 27% of steady-state ICa, an action blunted to 9% in the presence of the L-type Ca channel blocker verapamil (50 µM). The dopamine type 1 receptor (D1R) agonist SKF38393 (20 µM) inhibited ICa by 24%. The D1R antagonist SCH23390 (20 µM) reduced dopamine and SKF38393 inhibition. Dopamine slowed ICa activation, blocking ICa by 38% early in a voltage step. Enhanced early inhibition of ICa was eliminated by applying voltage prepulses to +120 mV for 100 ms, increasing ICa by 31% and 11% for early and steady-state currents, respectively. Voltage-dependent facilitation of ICa and block of dopamine inhibition after preincubation with a Gßγ-blocking peptide suggested involvement of Gßγ proteins in the D1R-mediated modulation. When the G protein activator guanosine 5'-O-(3-thiotriphosphate) (GTPγS) was added intracellularly, ICa was smaller and showed the same slowed kinetics seen during D1R activation. With GTPγS in the pipette, additional block of ICa by dopamine was only 6%. Strong depolarizing voltage prepulses restored the GTPγS-reduced early ICa amplitude by 36% and steady-state ICa amplitude by 3%. These results suggest that dopaminergic inhibition of ICa via D1Rs is primarily mediated through the action of Gßγ proteins in horizontal cells.

Effect of spiperone on mesenchymal multipotent stromal and hemopoietic stem cells under conditions of pulmonary fibrosis.

The antifibrotic properties of spiperone and its effect on stem and progenitor cells were studied on the model of reversible bleomycin-induced pulmonary fibrosis in C57Bl/6 mice. Spiperone reduced infiltration of the alveolar interstitium and alveolar ducts with inflammatory cells and prevented the growth of the connective tissue in the parenchyma of bleomycin lungs. Apart from anti-inflammatory effect, spiperone suppressed bone marrow hemopoietic cells (CD3, CD45R (B220), Ly6C, Ly6G (Gr1), CD11b (Mac1), TER-119)-, Sca-1+, c-Kit+, CD34- and progenitor hemopoietic cells (granulocyte-erythroid-macrophage-megakaryocytic and granulocyte CFU). Spiperone-induced disturbances of fi brogenesis were paralleled by restoration of endothelial cells in the lung parenchyma, reduction of the number of circulating bone marrow cells and lung mesenchymopoietic cells (mesenchymal multipotent stromal cells (CD31-, CD34-, CD45-, CD44+, CD73+, CD90+, CD106+) and progenitor fi broblast cells), and suppression of multilineage differentiation of multipotent mesenchymal stromal cells (including fi broblast-lineage cells).

Anti-inflammatory and antifibrotic effects of a combination of spiperone and immobilized hyaluronidase on partially reversible and irreversible toxic pneumofibrosis.

The possibility of boosting antifibrotic activity of testicular hyaluronidase immobilized on polyethylene oxide with spiperone was studied on the bleomycin models of a single (partially reversible pneumofibrosis) and repeated (irreversible pneumofibrosis) injuries to the alveolar epithelium in C57Bl/6 mice. The antifibrotic effect was more pronounced after successive treatment with immobilized hyaluronidase and spiperone than after individual treatment with each of the compounds: no collagen deposition in the parenchyma of bleomycin-damaged lungs was found. The decrease in inflammatory cell (lymphocytes, macrophages, neutrophils, plasma cells) infiltration of the alveoli and alveolar tracts interstitium in mice treated by immobilized hyaluronidase and spiperone did not differ from the anti-inflammatory effect of spiperone monotherapy.

The role of mesenchymal stem cells and serotonin in the development of experimental pancreatitis.

Pancreatitis was modeled before and after preliminary transplantation of stem cells and serotonin. It was demonstrated that transplantation of mesenchymal stem cells and activation of serotoninergic system prevent the development of pancreatitis.

Wnt5a-dopamine D2 receptor interactions regulate dopamine neuron development via extracellular signal-regulated kinase (ERK) activation.

The dopamine D2 receptor (D2R) plays an important role in mesencephalic dopaminergic neuronal development, particularly coupled with extracellular signal-regulated kinase (ERK) activation. Wnt5a protein is known to regulate the development of dopaminergic neurons. We analyzed the effect of Wnt5a on dopaminergic neuron development in mesencephalic primary cultures from wild-type (WT) and D2R knock-out (D2R(-/-)) mice. Treatment with Wnt5a increased the number and neuritic length of dopamine neurons in primary mesencephalic neuronal cultures from WT mice, but not from D2R(-/-) mice. The effect of Wnt5a was completely blocked by treatment with D2R antagonist or inhibitors of MAPK or EGFR. Wnt5a-mediated ERK activation in mesencephalic neuronal cultures was inhibited by treatment of D2R antagonist and EGFR inhibitors in WT mice. However, these regulations were not observed for D2R(-/-) mice. Co-immunoprecipitation and displacement of [(3)H]spiperone from D2R by Wnt5a demonstrated that Wnt5a could bind with D2R. This interaction was confirmed by GST pulldown assays demonstrating that the domain including transmembrane domain 4, second extracellular loop, and transmembrane domain 5 of D2R binds to Wnt5a. These results suggest that the interaction between D2R and Wnt5a has an important role in dopamine neuron development in association with EGFR and the ERK pathway.

Dopamine antagonists and brief vision distinguish lens-induced- and form-deprivation-induced myopia.

In eyes wearing negative lenses, the D2 dopamine antagonist spiperone was only partly effective in preventing the ameliorative effects of brief periods of vision (Nickla et al., 2010), in contrast to reports from studies using form-deprivation. The present study was done to directly compare the effects of spiperone, and the D1 antagonist SCH-23390, on the two different myopiagenic paradigms. 12-day old chickens wore monocular diffusers (form-deprivation) or -10 D lenses attached to the feathers with matching rings of Velcro. Each day for 4 days, 10 µl intravitreal injections of the dopamine D2/D4 antagonist spiperone (5 nmoles) or the D1 antagonist SCH-23390, were given under isoflurane anesthesia, and the diffusers (n = 16; n = 5, respectively) or lenses (n = 20; n = 6) were removed for 2 h immediately after. Saline injections prior to vision were done as controls (form-deprivation: n = 11; lenses: n = 10). Two other saline-injected groups wore the lenses (n = 12) or diffusers (n = 4) continuously. Axial dimensions were measured by high frequency A-scan ultrasonography at the start, and on the last day immediately prior to, and 3 h after the injection. Refractive errors were measured at the end of the experiment using a Hartinger's refractometer. In form-deprived eyes, spiperone, but not SCH-23390, prevented the ocular growth inhibition normally effected by the brief periods of vision (change in vitreous chamber depth, spiperone vs saline: 322 vs 211 µm; p = 0.01). By contrast, neither had any effect on negative lens-wearing eyes given similar unrestricted vision (210 and 234 µm respectively, vs 264 µm). The increased elongation in the spiperone-injected form-deprived eyes did not, however, result in a myopic shift, probably due to the inhibitory effect of the drug on anterior chamber growth (drug vs saline: 96 vs 160 µm; p < 0.01). Finally, spiperone inhibited the vision-induced transient choroidal thickening in form-deprived eyes, while SCH-23390 did not. These results indicate that the dopaminergic mechanisms mediating the protective effects of brief periods of unrestricted vision differ for form-deprivation versus negative lens-wear, which may imply different growth control mechanisms between the two.

Dopamine as an anorectic neuromodulator in the cockroach Rhyparobia maderae.

Insects, including cockroaches, self-select a balanced diet when faced with different nutrient choices. For self-selection to be carried out effectively, insects possess neuroregulatory systems to control their food intake. In the present study, we examined the role of the neurotransmitter dopamine (DA) in the feeding regulation of the Madeira cockroach (Rhyparobia maderae). When R. maderae nymphs were injected with 20 µl of 100 mmol l(-1) DA, they showed an 83.3% reduction in sucrose intake and a 78.9% reduction in total intake compared with saline-injected controls. The DA agonist, 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (6,7-ADTN) (100 mmol l(-1) in 1 µl), caused a significant reduction in sucrose feeding, reducing feeding by 47.3% compared with saline-injected controls. Protein feeding was also significantly reduced by 6,7-ADTN to 62%. Rhyparobia maderae nymphs injected with the DA antagonist chlorpromazine (100 mmol l(-1) in 1 µl) did not differ significantly from control nymphs in their feeding behavior. Interestingly, R. maderae nymphs injected with 2 µl or 5 µl chlorpromazine (100 mmol l(-1)) showed significantly increased mortality rates of 47.5% or 66.7%, respectively. The DA antagonist, spiperone (100 mmol l(-1) in 1 µl), caused a significant feeding response, showing an increase in feeding in both sucrose (310.6%) and total intake (236.3%). Casein feeding in R. maderae nymphs was also elevated (70.8%) but this was not statistically significant. The experiments with DA, the DA agonist 6,7-ADTN and the DA antagonist spiperone strongly suggest that the neurotransmitter DA is involved in regulating feeding in the cockroach R. maderae.

In vitro effects of both dopaminergic and enkephalinergic antagonists on the ovarian growth of Cherax quadricarinatus (Decapoda, Parastacidae), at different periods of the reproductive cycle.

The in vitro effect of both spiperone (dopaminergic antagonist) and naloxone (enkephalinergic antagonist), was assayed on small pieces of ovary dissected from C. quadricarinatus females, with the eventual addition of some neuroendocrine organs, such as thoracic ganglion or eyestalk tissue. The incorporation of tritiated leucine by the ovary was measured in order to estimate the ovarian growth. During the post-reproductive period, both mentioned antagonists were able to significantly stimulate the ovary in the presence of thoracic ganglion, but did not produce any significant effect in the preparation containing ovary and eyestalk tissue, or only ovary. No significant effects of the assayed antagonists were noted during the pre-reproductive period. These results were in accordance with previous models describing the neuroendocrine control of crustacean reproduction, and represent new findings about the hormonal context in different periods of the reproductive cycle of crayfish. Besides, by means of the experimental combination of the tested antagonists with dopamine or met-enkephalin, a new model dealing with the interaction of these two neurotransmitters on the hormonal secretion of thoracic ganglion has been proposed.

Spiperone Stimulates Regeneration in Pulmonary Endothelium Damaged by Cigarette Smoke and Lipopolysaccharide.

BACKGROUND: Endothelial dysfunction and destruction of the pulmonary microcirculation are important pathogenic factors in chronic obstructive pulmonary disease (COPD). In COPD, bronchial obstruction is associated with endothelial dysfunction. Thus, new pharmacological treatment options aimed at restoring the pulmonary endothelium represent a clinical need in COPD therapy. Notch1 has been shown to protect cells against apoptosis, inflammation, and oxidative stress caused by cigarette smoke extract (CSE). Therefore, drug which effect on Notch1 may be a potential therapeutic target for COPD in the future. METHODS: In this study, we assessed the potential of spiperone to mediate regeneration of pulmonary endothelium in model of pulmonary emphysema induced by a CSE and lipopolysaccharide (LPS) in female C57BL/6 mice. RESULTS: Spiperone increased the number of capillaries as well as the expression of the CD31 in the alveolar tissue compared to the controls. Moreover, application of spiperone prevented alveolar wall destruction (DI), and reduced the area of emphysema. Lastly, we demonstrated that spiperone positively influenced mobilization and migration of endothelial progenitor cells (EPC, CD45-CD34+CD31+), CD309+-endothelial cells, and angiogenesis precursors (CD45-CD117+CD309+) into the lung. Spiperone administration significantly reduced the number Notch1 positive CD309+-endothelial cells and Notch1+ EPCs. CONCLUSION: Overall, our results suggest that spiperone mediates endothelial regeneration in an animal model of COPD. Thus, it could represent a novel therapeutic approach for treatment of emphysema associated with COPD.

Early life exposure to poly I:C impairs striatal DA-D2 receptor binding, myelination and associated behavioural abilities in rats.

Early-life viral infections critically influence the brain development and have been variously reported to cause neuropsychiatric diseases such as Schizophrenia, Parkinson's diseases, demyelinating diseases, etc. To investigate the alterations in the dopaminergic system, myelination and associated behavioral impairments following neonatal viral infection, the viral immune activation model was created by an intraperitoneal injection of Poly I:C (5 mg/kg bw/ip) to neonatal rat pups on PND-7. The DA-D2 receptor binding was assessed in corpus striatum by using 3H-Spiperone at 3, 6 and 12 weeks of age. MOG immunolabelling was performed to check myelination stature and myelin integrity, while corpus callosum calibre was assessed by Luxol fast blue staining. Relative behavioral tasks i.e., motor activity, motor coordination and neuromuscular strength were assessed by open field, rotarod and grip strength meter respectively at 3, 6 and 12 weeks of age. Following Poly I:C exposure, a significant decrease in DA-D2 receptor binding, reduction in corpus callosum calibre and MOG immunolabelling indicating demyelination and a significant decrease in locomotor activity, neuromuscular strength and motor coordination signify motor deficits and hypokinetic influence of early life viral infection. Thus, the findings suggest that early life poly I:C exposure may cause demyelination and motor deficits by decreasing DA-D2 receptor binding affinity.

Levodopa inhibits the development of lens-induced myopia in chicks.

Animal models have demonstrated a link between dysregulation of the retinal dopamine system and the development of myopia (short-sightedness). We have previously demonstrated that topical application of levodopa in chicks can inhibit the development of form-deprivation myopia (FDM) in a dose-dependent manner. Here, we examine whether this same protection is observed in lens-induced myopia (LIM), and whether levodopa's protection against FDM and LIM occurs through a dopamine D1- or D2-like receptor mechanism. To do this, levodopa was first administered daily as an intravitreal injection or topical eye drop, at one of four ascending doses, to chicks developing LIM. Levodopa's mechanism of action was then examined by co-administration of levodopa injections with D1-like (SCH-23390) or D2-like (spiperone) dopamine antagonists in chicks developing FDM or LIM. For both experiments, levodopa's effectiveness was examined by measuring axial length and refraction after 4 days of treatment. Levodopa inhibited the development of LIM in a dose-dependent manner similar to its inhibition of FDM when administered via intravitreal injections or topical eye drops. In both FDM and LIM, levodopa injections remained protective against myopia when co-administered with SCH-23390, but not spiperone, indicating that levodopa elicits its protection through a dopamine D2-like receptor mechanism in both paradigms.

Cysteamine: a potent and specific depletor of pituitary prolactin.

Cysteamine rapidly reduces the concentration of prolactin in pituitary tissue in vivo and in vitro. The effect is dose-dependent, reversible, and cannot be accounted for by prolactin release. Cysteamine does not appear to exert its effect through dopamine receptors and does not alter lactotrope morphology, as determined by electron microscopy.

Tail pinch induces eating in sated rats which appears to depend on nigrostriatal dopamine.

Mild tail pinch reliably and rapidly induced eating, gnawing, or licking behavior in all animals tested. Eating was by far the predominant response. Pharmacological analysis of the involvement of the brain catecholamines in tail-pinch behavior suggests that it is critically dependent on the nigrostriatal dopamine system.

Receptors for dopamine and somatostatin: formation of hetero-oligomers with enhanced functional activity.

Somatostatin and dopamine are two major neurotransmitter systems that share a number of structural and functional characteristics. Somatostatin receptors and dopamine receptors are colocalized in neuronal subgroups, and somatostatin is involved in modulating dopamine-mediated control of motor activity. However, the molecular basis for such interaction between the two systems is unclear. Here, we show that dopamine receptor D2R and somatostatin receptor SSTR5 interact physically through hetero-oligomerization to create a novel receptor with enhanced functional activity. Our results provide evidence that receptors from different G protein (heterotrimeric guanine nucleotide binding protein)-coupled receptor families interact through oligomerization. Such direct intramembrane association defines a new level of molecular crosstalk between related G protein-coupled receptor subfamilies.

A G protein couples serotonin and GABAB receptors to the same channels in hippocampus.

Both serotonin and the selective gamma-aminobutyric acidB (GABAB) agonist, baclofen, increase potassium (K+) conductance in hippocampal pyramidal cells. Although these agonists act on separate receptors, the potassium currents evoked by the agonists are not additive, indicating that the two receptors share the same potassium channels. Experiments with hydrolysis-resistant guanosine triphosphate (GTP) and guanosine diphosphate analogs and pertussis toxin indicate that the opening of the potassium channels by serotonin and GABAB receptors involves a pertussis toxin-sensitive GTP-binding (G) protein, which may directly couple the two receptors to the potassium channel.