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Las fosfodiesterasas de nucleótidos cíclicos (PDEs) de la subfamilia 4 (PDE4) son responsables de la hidrólisis y compartimentalización subcelular del adenosín monofosfato cíclico (AMPc), segundo mensajero que modula la funcionalidad vascular. Habíamos demostrado que la isoforma B de la PDE4 (PDE4B) se induce en el aneurisma de aorta abdominal (AAA) y que la inhibición de la actividad PDE4 mediante rolipram limita la formación de aneurismas experimentales. En este estudio hemos profundizado en los mecanismos que subyacen al efecto beneficioso del rolipram sobre el AAA.

ABSTRACTGlioblastoma (GBM) is the most aggressive primary brain tumor, exhibiting a high rate of recurrence and poor prognosis. Surgery and chemoradiation with temozolomide (TMZ) represent the standard of care, but, in most cases, the tumor develops resistance to further treatment and the patients succumb to disease. Therefore, there is a great need for the development of well-tolerated, effective drugs that specifically target chemoresistant gliomas. NEO214 was generated by covalently conjugating rolipram, a PDE4 (phosphodiesterase 4) inhibitor, to perillyl alcohol, a naturally occurring monoterpene related to limonene. Our previous studies in preclinical models showed that NEO214 harbors anticancer activity, is able to cross the blood-brain barrier (BBB), and is remarkably well tolerated. In the present study, we investigated its mechanism of action and discovered inhibition of macroautophagy/autophagy as a key component of its anticancer effect in glioblastoma cells. We show that NEO214 prevents autophagy-lysosome fusion, thereby blocking autophagic flux and triggering glioma cell death. This process involves activation of MTOR (mechanistic target of rapamycin kinase) activity, which leads to cytoplasmic accumulation of TFEB (transcription factor EB), a critical regulator of genes involved in the autophagy-lysosomal pathway, and consequently reduced expression of autophagy-lysosome genes. When combined with chloroquine and TMZ, the anticancer impact of NEO214 is further potentiated and unfolds against TMZ-resistant cells as well. Taken together, our findings characterize NEO214 as a novel autophagy inhibitor that could become useful for overcoming chemoresistance in glioblastoma.Abbreviations:ATG: autophagy related; BAFA1: bafilomycin A1; BBB: blood brain barrier; CQ: chloroquine; GBM: glioblastoma; LAMP1: lysosomal associated membrane protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MGMT: O-6-methylguanine-DNA methyltransferase; MTOR: mechanistic target of rapamycin kinase; MTORC: MTOR complex; POH: perillyl alcohol; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TMZ: temozolomide

A recent study conducted at Yamaguchi University investigated the effects of rolipram, a phosphodiesterase inhibitor, on brain tissue regeneration. The study used mice injected with trimethyltin chloride as an animal model for hippocampal tissue regeneration. The results showed that daily administration of rolipram improved the replenishment of neurons in the dentate gyrus and increased the survival of newborn neurons. Additionally, rolipram reduced neuroinflammation and the activation of microglia. These findings suggest that rolipram effectively promotes brain tissue regeneration. [Extracted from the article]

A preprint abstract from biorxiv.org discusses the potential of the PDE4 inhibitor Rolipram in breast cancer treatment. The study found that Rolipram can down-regulate MMP2 and MMP9 levels, which are important markers of metastasis in breast cancer cell lines. The inhibitor was also found to alter the enzymatic activities of these MMPs independently of cAMP-PKA signaling. In vitro experiments using primary cells from breast cancer patients further supported these findings. The study suggests that Rolipram may have off-target effects on proteins involved in metastasis, making it a potential therapeutic option for breast cancer. However, it is important to note that this preprint has not been peer-reviewed. [Extracted from the article]

A preprint abstract from biorxiv.org discusses the potential therapeutic implications of the PDE4 inhibitor Rolipram in breast cancer treatment. The abstract highlights that Rolipram has been found to down-regulate MMP2 and MMP9 levels, which are important markers of metastasis in breast cancer cell lines. The study also explores the inhibitory mechanism of Rolipram on MMP2 and MMP9 through zymographic studies, ligand-based target prediction, and molecular docking. In vitro experiments using primary cells from breast cancer patients further support the ability of Rolipram to control breast cancer by altering the enzymatic activities of MMP2 and MMP9. However, it is important to note that this preprint has not been peer-reviewed. [Extracted from the article]

A novel approach is reported for the enantioselective flow synthesis of rolipram comprising a telescoped asymmetric conjugate addition–oxidative aldehyde esterification sequence followed by trichlorosilane-mediated nitro group reduction and concomitant lactamization. The telescoped process takes advantage of a polystyrene-supported chiral organocatalyst along with in situ-generated persulfuric acid as a robust and scalable oxidant for direct aldehyde esterification. This approach demonstrates significantly improved productivity compared with earlier methodologies while ensuring environmentally benign metal-free conditions.

A preprint abstract from biorxiv.org discusses the potential use of the PDE4 inhibitor rolipram in repressing the hedgehog signaling pathway to regress breast cancer. The study found that rolipram increased levels of cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA), which led to the transformation of GLI2FL and GLI3FL transcription factors into repressor forms. This resulted in a reduction in the level of GLI1 transcription factor over time. Rolipram also showed promising results in altering wound healing capability and reducing tumor weight and volume in mice models. The study suggests that rolipram could be an effective inhibitor of the hedgehog signaling pathway in controlling breast cancer progression and metastasis. However, it is important to note that this preprint has not been peer-reviewed. [Extracted from the article]

Researchers at Indiana University have conducted a study on selective phosphodiesterase-4 inhibitors (PDE4 inhibitors) and their potential to treat Autosomal Dominant Osteopetrosis type II (ADO2), a rare bone disease. The study found that ADO2 osteoclasts have reduced levels of cyclic adenosine monophosphate (cAMP), a critical molecule for osteoclast activity. However, regulating cAMP levels through PDE4 inhibition with drugs like roflumilast and rolipram was found to improve osteoclast activity in ADO2 mice. These findings contribute to the understanding of ADO2 osteoclast dysfunction and may lead to the development of therapeutic approaches for affected patients. [Extracted from the article]

A recent study conducted at Clemson University in South Carolina has provided new insights into the use of nanoparticles in treating spinal cord injuries. The researchers developed a copolymer called poly (lactide-co-glycolide)-graft-polyethylenimine (PgP) that can deliver a PDE4 inhibitor called Rolipram. The study found that the Rolipram-loaded PgP nanoparticles were able to increase cAMP levels and reduce secondary injury, such as inflammation and cell death, in a rat model of spinal cord injury. Additionally, the nanoparticles improved motor function recovery in the rats. This research has been peer-reviewed and published in the journal Nanomedicine Nanotechnology Biology and Medicine. [Extracted from the article]

Our news editors obtained a quote from the research from Shandong First Medical University & Shandong Academy of Medical Sciences: "APP/PS1/tau mice (10 months old) were treated with or without daily intraperitoneal injections of rolipram for 10 days. For more information on this research see: Rolipram ameliorates memory deficits and depression-like behavior in APP/PS1/tau triple transgenic mice: involvement of neuroinflammation and apoptosis via cAMP signaling. [Extracted from the article]

Cognitive impairment often occurs in Parkinson's disease (PD), but the mechanism of onset remains unknown. Recently, we reported that PD model mice produced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) show facilitation of hippocampal memory extinction, which may be the cause of cognitive impairment in PD. When we examined the cAMP/CREB signaling in the hippocampus, decreased levels of cAMP and phosphorylated CREB were observed in the dentate gyrus (DG) of MPTP-treated mice. Administration of rolipram improved the memory deficits with concomitant recovery of cAMP and phosphorylated CREB levels, suggesting that reduced cAMP/CREB signaling in the DG leads to cognitive impairment in MPTP-treated mice.

Latent toxoplasmosis always has the risk of reactivation leading to significant sequelae. The available medications, for chronic toxoplasmosis, are awfully limited by resistance of Toxoplasmacysts. Therefore, there is a growing necessity for novel therapeutic approaches. Agents increasing cAMP levels and downregulating proinflammatory cytokine could inhibit Toxoplasmaconversion to the bradyzoite stage. This study explores a potential immunomodulatory effect of rolipram, a PDE4 inhibitor, on the course of experimental toxoplasmosis and links this role to deterrence of the resistant chronic phase of the disease.

Objective: Forskolin, an activator of adenylate cyclase and rolipram a selective inhibitor of phosphodiesterase 4, stimulate lipolysis and inhibit body weight increase by increasing cyclic adenosine monophosphate (cAMP) levels. This study was aimed to investigate the effects of them on leptin, resistin and adiponectin levels in diet induced obesity in rats.

Following spinal cord injury (SCI), both an inhibitory environment and lack of intrinsic growth capacity impede axonal regeneration. In a previous study, prevention of cyclic adenosine monophosphate (AMP) hydrolysis by the phosphodiesterase-4 inhibitor rolipram, in combination with Schwann cell (SC) grafts, promoted significant supraspinal and proprioceptive fiber growth and/or sparing and improved locomotion. In another study, transplanted SCs transduced to generate a bifunctional neurotrophin (D15A) led to significant increases in graft SCs and axons, including supraspinal and myelinated axons. Here we studied the growth and myelination of local and supraspinal axons and functional outcome following the combination of rolipram administration and neurotrophin-transduced SC implantation after SCI. Rolipram was administered subcutaneously for 4 weeks immediately after contusion at vertebral T8 (25.0-mm weight drop, MASCIS impactor). GFP or GFP-D15A-transduced SCs were injected into the injury epicenter 1 week after SCI. GFP-D15A SC grafts and GFP SC grafts with rolipram contained significantly more serotonergic fibers compared to GFP SCs. SC myelinated axons were increased significantly in GFP SC with rolipram-treated animals compared to animals receiving SCI alone. Rolipram administered with either GFP or GFP-D15A SCs significantly increased numbers of brain stem-derived axons below the lesion/implant area and improved hindlimb function. Compared to the single treatments, the combination led to the largest SC grafts, the highest numbers of serotonergic fibers in the grafts, and increased numbers of axons from the reticular formation below the lesion/implant area and provided the greatest improvement in hindlimb function. These findings demonstrate the therapeutic potential for a combination therapy involving the maintenance of cyclic AMP levels and neurotrophin-transduced SCs to repair the subacutely injured spinal cord.

Microcirculatory dysfunction is correlated with increased mortality among septic patients and is believed to be a major contributor to the development of acute kidney injury (AKI). Rolipram, a selective phosphodiesterase 4 (PDE4) inhibitor, has been shown to reduce microvascular permeability and in the kidney, increase renal blood flow (RBF). This led us to investigate its potential to improve the renal microcirculation and preserve renal function during sepsis using a murine cecal ligation and puncture (CLP) model to induce sepsis. Rolipram, tested at doses of 0.3–10 mg/kg i.p., acutely restored capillary perfusion in a bell-shaped dose-response effect with 1 mg/kg being the lowest most efficacious dose. This dose also acutely increased RBF despite transiently decreasing mean arterial pressure. Rolipram also reduced renal microvascular permeability. It is noteworthy that delayed treatment with rolipram at 6 hours after CLP restored the renal microcirculation, reduced blood urea nitrogen and serum creatinine, and increased glomerular filtration rate at 18 hours. However, delayed treatment with rolipram did not reduce serum nitrate/nitrite levels, a marker of nitric oxide production, nor reactive nitrogen species generation in renal tubules. These data show that restoring the microcirculation with rolipram, even with delayed treatment, is enough to improve renal function during sepsis despite the generation of oxidants and suggest that PDE4 inhibitors should be evaluated further for their ability to treat septic-induced AKI.

Anti-inflammatory and antifibrotic effects of the broad spectrum phosphodiesterase (PDE) inhibitor pentoxifylline have suggested an important role for cyclic nucleotides in the pathogenesis of hepatic fibrosis; however, studies examining the role of specific PDEs are lacking. Endotoxemia and Toll-like receptor 4 (TLR4)-mediated inflammatory and profibrotic signaling play a major role in the development of hepatic fibrosis. Because cAMP-specific PDE4 critically regulates lipopolysaccharide (LPS)-TLR4–induced inflammatory cytokine expression, its pathogenic role in bile duct ligation-induced hepatic injury and fibrogenesis in Sprague-Dawley rats was examined. Initiation of cholestatic liver injury and fibrosis was accompanied by a significant induction of PDE4A, B, and D expression and activity. Treatment with the PDE4-specific inhibitor rolipram significantly decreased liver PDE4 activity, hepatic inflammatory and profibrotic cytokine expression, injury, and fibrosis. At the cellular level, in relevance to endotoxemia and inflammatory cytokine production, PDE4B was observed to play a major regulatory role in the LPS-inducible tumor necrosis factor (TNF) production by isolated Kupffer cells. Moreover, PDE4 expression was also involved in the in vitro activation and transdifferentiation of isolated hepatic stellate cells (HSCs). Particularly, PDE4A, B, and D upregulation preceded induction of the HSC activation marker α-smooth muscle actin (α-SMA). In vitro treatment of HSCs with rolipram effectively attenuated α-SMA, collagen expression, and accompanying morphologic changes. Overall, these data strongly suggest that upregulation of PDE4 expression during cholestatic liver injury plays a potential pathogenic role in the development of inflammation, injury, and fibrosis.

Here we show that administration of the phosphodiesterase type 4 (PDE4) inhibitor rolipram into the basolateral complex of the amygdala (BLA) at a specific time interval after training enhances memory consolidation and induces memory persistence for novel object recognition (NOR) in rats. Intra-BLA infusion of rolipram immediately, 1.5 h, or 6 h after training had no effect on retention tested at 1, 7, and 14 d later. However, rolipram infused 3 h post-training promoted memory persistence for up to at least 14 d. The findings suggest that PDE4 inhibition in the BLA can enhance long-term memory formation when induced specifically 3 h after learning.

Cyclic adenosine monophosphate (cAMP) is the common second messenger in signal-transduction cascades originating at a number of monoamine receptors involved in neurotransmission, cardiac function and smooth muscle contraction. Altered regulation of cAMP synthesis (at receptors, G-protein subunits or adenylyl cyclase) and breakdown by phosphodiesterase (PDE) enzymes have been implicated in a number of pathologies. The PDE4 inhibitor (R)-rolipram, and the less active (S)- enantiomer, have been labeled with carbon-11 and characterized by in vivo and in vitro experiments for use in the evaluation of altered PDE4 levels in the brain and cardiac tissues. (R)-[11C]Rolipram has been shown to bind selectively to PDE4 over other PDE isozymes, with specific binding reflecting approximately 80 and 40% of the total detected radioactivity in the rat brain and the heart, respectively. Tracer retention in PDE4-rich tissues is increased by cAMP-elevating treatments, as detected by in vivo PET studies and ex vivo biodistribution experiments. In vivo PET imaging studies display strong region-specific signal in the brain and heart, as evaluated in rats, pigs, monkeys and humans. Impaired cAMP-mediated signaling was observed in animal models of aging, obesity, anthracycline-induced cardiotoxicity and myocardial infarction using (R)-[11C]rolipram. Given the critical role of cAMP in multiple hormonal pathways, the good safety profile and well-characterized pharmacokinetics, (R)-[11C]rolipram PET imaging provides a novel tool for serial monitoring of cAMP-mediated signaling at the PDE4 level, yielding insight into pathological progression with potential for directing therapy.

AbstractBackground/Objective:High cervical spinal cord hemisection interrupts descending respiratory drive from the rostral ventral respiratory group in the medulla to the ipsilateral phrenic motoneurons. Hemisection results in the paralysis of the ipsilateral hemidiaphragm. Chronic administration of rolipram, a specific phosphodiesterase-IV inhibitor, promotes synaptic plasticity and restores phrenic nerve function after a high cervical spinal cord lesion. Here, we test the hypothesis that an acute administration of rolipram will increase spinal and medullary levels of 3′,5′-cyclic adenosine monophosphate (cAMP) and induce phrenic nerve recovery after cervical (C2) spinal cord hemisection.Methods:Male Sprague-Dawley rats were subjected to left C2 hemisection surgery 1 week before experimentation. Bilateral phrenic nerve activity was recorded in anesthetized, vagotomized, and pancuronium paralyzed rats, and rolipram was intravenously applied (2 mg/kg).Results:Intravenous administration of rolipram increased phrenic nerve output in uninjured control and left C2 spinal cord-hemisected rats. In addition, rolipram restored respiratory-related activity to the left phrenic nerve made quiescent by the hemisection. In both uninjured and hemisected rats, rolipram significantly enhanced phrenic inspiratory burst amplitude and burst area compared with predrug values. Also, rolipram concomitantly increased spinal and medullary cAMP.Conclusions:These results suggest that a phosphodiesterase inhibitor capable of elevating cAMP levels can enhance phrenic nerve output and restore respiratory-related phrenic nerve function after high cervical spinal cord injury. Thus, targeting the cAMP signaling cascade can be a useful therapeutic approach in promoting synaptic efficacy and respiratory recovery after cervical spinal cord injury.

Periventricular white matter injury is the leading cause of cerebral palsy in premature infants for which no effective treatments are available. Our previous studies have demonstrated that pharmacological activation of the cAMP response element-binding protein (CREB) signaling pathway, before hypoxic-ischemia protected against neuronal injury in neonatal rats. We examined whether rolipram, a phosphodiesterase type IV inhibitor, treatment after hypoxic-ischemia is protective against white matter injury in neonatal rats. Rats were exposed to hypoxia-ischemia (HI) on P7 and then treated with daily injections of various doses of rolipram (P7–P11). Immunohistochemical staining for myelin basic protein, ED1, glial fibrillary acidic protein, CREB and O1 were examined on P11. We found that the periventricular white matter and deep cortical lesions were exacerbated by rolipram administration after HI injury. The lesions in the rolipram-treated group also showed increased astrogliosis and increased CREB phosphorylation in the activated microglia and astrocytes. Furthermore, the rolipram-posttreated HI group had markedly depleted preoligodendrocytes in the ipsilateral hemisphere, which may be related to decreased preoligodendrocytes proliferation after rolipram treatment per se. These data suggest that rolipram treatment after hypoxic-ischemia is not protective; in contrast, rolipram may exacerbate hypoxic-ischemic white matter injury in neonatal rat brains.

Periventricular white matter injury is the leading cause of cerebral palsy in premature infants for which no effective treatments are available. Our previous studies have demonstrated that pharmacological activation of the cAMP response element-binding protein (CREB) signaling pathway, before hypoxic-ischemia protected against neuronal injury in neonatal rats. We examined whether rolipram, a phosphodiesterase type IV inhibitor, treatment after hypoxic-ischemia is protective against white matter injury in neonatal rats. Rats were exposed to hypoxia-ischemia (HI) on P7 and then treated with daily injections of various doses of rolipram (P7–P11). Immunohistochemical staining for myelin basic protein, ED1, glial fibrillary acidic protein, CREB and O1 were examined on P11. We found that the periventricular white matter and deep cortical lesions were exacerbated by rolipram administration after HI injury. The lesions in the rolipram-treated group also showed increased astrogliosis and increased CREB phosphorylation in the activated microglia and astrocytes. Furthermore, the rolipram-posttreated HI group had markedly depleted preoligodendrocytes in the ipsilateral hemisphere, which may be related to decreased preoligodendrocytes proliferation after rolipram treatment per se. These data suggest that rolipram treatment after hypoxic-ischemia is not protective; in contrast, rolipram may exacerbate hypoxic-ischemic white matter injury in neonatal rat brains.

To assess the combination effect of calcitonin and the phosphodiesterase 4 inhibitor rolipram on osteoclastogenesis, adherent cell-depleted bone marrow cells from mouse tibia and femur (ACD-BMCs), which were cultured in the presence of 25 ng/ml colony-stimulating factor 1 (CSF-1) and 100 ng/ml soluble receptor activator of NF-κB ligand (sRANKL), were utilized. Calcitonin inhibited formation of tartrate-resistant acid phosphatase-positive multinucleated cells, as mature osteoclasts, by 70% even at 20 pM, whereas rolipram (10 µM) scarcely affected osteoclast formation; in contrast, the combination of both agents led to significant inhibition of multinucleation and pit formation ability of osteoclasts. The combined administration of calcitonin and rolipram attenuated calcitonin receptor mRNA expression in comparison to treatment with either agent alone, whereas expression of RANK and CSF-1 receptor mRNAs was unchanged. Alone, these agents scarcely elevated intracellular cyclic AMP (cAMP) concentration; however, combination treatment with both agents significantly increased cAMP concentration in osteoclast progenitors and osteoclasts. The combination effect was abolished by H-89, an inhibitor of protein kinase A. It appears that rolipram inhibited hydrolysis of cAMP formed by calcitonin in cells and potentiated the inhibitory effect of calcitonin on osteoclastogenesis. The escape phenomenon following calcitonin treatment may also be prevented by concomitant treatment with the phosphodiesterase 4 inhibitor.To assess the combination effect of calcitonin and the phosphodiesterase 4 inhibitor rolipram on osteoclastogenesis, adherent cell-depleted bone marrow cells from mouse tibia and femur (ACD-BMCs), which were cultured in the presence of 25 ng/ml colony-stimulating factor 1 (CSF-1) and 100 ng/ml soluble receptor activator of NF-κB ligand (sRANKL), were utilized. Calcitonin inhibited formation of tartrate-resistant acid phosphatase-positive multinucleated cells, as mature osteoclasts, by 70% even at 20 pM, whereas rolipram (10 µM) scarcely affected osteoclast formation; in contrast, the combination of both agents led to significant inhibition of multinucleation and pit formation ability of osteoclasts. The combined administration of calcitonin and rolipram attenuated calcitonin receptor mRNA expression in comparison to treatment with either agent alone, whereas expression of RANK and CSF-1 receptor mRNAs was unchanged. Alone, these agents scarcely elevated intracellular cyclic AMP (cAMP) concentration; however, combination treatment with both agents significantly increased cAMP concentration in osteoclast progenitors and osteoclasts. The combination effect was abolished by H-89, an inhibitor of protein kinase A. It appears that rolipram inhibited hydrolysis of cAMP formed by calcitonin in cells and potentiated the inhibitory effect of calcitonin on osteoclastogenesis. The escape phenomenon following calcitonin treatment may also be prevented by concomitant treatment with the phosphodiesterase 4 inhibitor.

Inhibition of type IV phosphodiesterase (PDE IV) activity reduces the production of various proinflammatory cytokine and suppresses neutrophil activation. Nonsteroidal anti-inflammatory drugs such as aspirin induce gastric mucosal lesions. In the pathogenesis of aspirin-induced gastric mucosal lesion, the contributions, of activated inflammatory cells and proinflammatory cytokine production are critical. The specific PDE IV inhibitor rolipram is known to be a potent inhibitor of inflammation by increasing intracellular cyclic AMP in leukocytes. The aim of the present study was to determine whether rolipram can ameliorate aspirin-induced gastric mucosal lesions in rats and whether the agent can inhibit the inrease in neutrophil accumulation and the production of proinflammatory cytokines. Gastric lesions were produced by administration of aspirin (200 mg/kg) and HCl (0.15 N; 8.0 ml/kg). Rolipram was injected 30 min before aspirin administration. The tissue myeloperoxidase concentration in gastric mucosa was measured as an indicat or of neutrophil infiltration. The gastric mucosal concentrations of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were determined by ELISA. The intragastric administration of aspirin induced multiple hemorrhagic erosions in rat gastric mucosa. Gastric mucosal lesions induced by aspirin were significantly inhibited by treatment with rolipram. The mucosal myeloperoxidase concentration was also suppressed by rolipram. Increases in the gastric content of TNF-α and IL-1β after aspirin administration were inhibited by pretreatment with rolipram. We demonstrated that the specific type IV PDE inhibitor, rolipram, could have a potent antiulcer effect, presumably mediated by its anti-inflammatory properties.

The aim of this study was to compare the positive inotropic effects of 3 different agents with 3 different mechanisms of actions-levosimendan, rolipram, and dobutamine-on human atrial trabecular muscles. Samples of right atrial appendage (1 cm2, 500-1000 mg) were removed and immersed in preoxygenated and modified Tyrode solution. In oxygenated Tyrode solution, preparations were used to investigate the concentration-effect relationship of levosimendan, dobutamine, and rolipram on percentage developed tension (DT), from 10−9to 10−4M, each concentration for 15 minutes. All 3 agents produced concentration-dependent increments in DT. We found that levosimendan was the most efficacious positive inotropic agent on isolated human atrial trabeculae. Both the sensitivity (pD2) and maximum response (Emax) of human atrial trabeculae to levosimendan (6.711 ± 0.26 and 23.2 ± 2.2 mN, respectively) were significantly greater than those of dobutamine (6.663 ± 0.19 and 17.6 ± 2.8 mN) and rolipram (6.497 ± 0.18 and 15.0 ± 1.0 mN). pD2and Emaxvalues for dobutamine were significantly higher than those for rolipram. It was suggested that because of its potential to enhance cardiac performance without predisposition to calcium-induced arrhythmias, levosimendan might be more useful as a positive inotropic agent in clinical practice.

The present study was designed to investigate the effect of the phosphodiesterase IV inhibitor rolipram on Th1 and Th2 immune responses in mice. Mice were immunized subcutaneously at the base of the tail with ovalbumin (OVA) emulsified with complete Freund's adjuvant (day 0) and were treated daily with oral administration of various doses of rolipram from days 0 to 20. On day 21, production of anti‐OVA IgG and proliferative responses to the antigen were determined. Anti‐OVA IgG2a and interferon‐γ (IFN‐γ), as indicators of Th1 responses, and anti‐OVA IgG1 and interleukin‐10 (IL‐10), as indicators of Th2 responses, were also measured. The results showed that treatment with rolipram failed to affect the production of OVA‐specific IgG but decreased the proliferation of spleen cells to the antigen. Its inhibitory effect on these immune responses was correlated with a marked decrease in IFN‐γ but not IL‐10 production, although neither anti‐OVA IgG2a nor IgG1 production was affected by rolipram. These results suggest that rolipram may preferentially inhibit Th1 responses more effectively than Th2 responses. Administration of rolipram resulted in suppression of antigen (OVA)‐induced arthritis in mice. The suppression of joint inflammation by rolipram was associated with the inhibition of the OVA‐specific proliferative responses of spleen cells and IFN‐γ secretion. These results indicate that rolipram may be effective in regulating Th1‐mediated diseases such as rheumatoid arthritis.

The present study was designed to investigate the effect of the phosphodiesterase IV inhibitor rolipram on Th1 and Th2 immune responses in mice. Mice were immunized subcutaneously at the base of the tail with ovalbumin (OVA) emulsified with complete Freund's adjuvant (day 0) and were treated daily with oral administration of various doses of rolipram from days 0 to 20. On day 21, production of anti-OVA IgG and proliferative responses to the antigen were determined. Anti-OVA IgG2a and interferon-γ (IFN-γ), as indicators of Th1 responses, and anti-OVA IgG1 and interleukin-10 (IL-10), as indicators of Th2 responses, were also measured. The results showed that treatment with rolipram failed to affect the production of OVA-specific IgG but decreased the proliferation of spleen cells to the antigen. Its inhibitory effect on these immune responses was correlated with a marked decrease in IFN-γ but not IL-10 production, although neither anti-OVA IgG2a nor IgG1 production was affected by rolipram. These results suggest that rolipram may preferentially inhibit Th1 responses more effectively than Th2 responses. Administration of rolipram resulted in suppression of antigen (OVA)-induced arthritis in mice. The suppression of joint inflammation by rolipram was associated with the inhibition of the OVA-specific proliferative responses of spleen cells and IFN-γ secretion. These results indicate that rolipram may be effective in regulating Th1-mediated diseases such as rheumatoid arthritis.

Piclamilast is a type 4 phosphodiesterase (PDE4) inhibitor with equal affinity for the high-affinity rolipram binding site (HARBS) and low-affinity rolipram binding site (LARBS). The binding of [3H]piclamilast to preparations of rat brain and peripheral tissue was investigated and compared with that of [3H]rolipram. [3H]piclamilast binding was high-affinity, saturable, reversible, and partially Mg2+-dependent. Binding was detected both to membrane and soluble fractions, with Kdvalues of 3.1 and 4.5 nM, respectively. The Bmaxvalues for [3H]piclamilast were about 1.5-fold greater than that of [3H]rolipram binding, suggesting that [3H]piclamilast, but not [3H]rolipram, binds to LARBS as well as the HARBS. The HARBS was present in all the brain regions examined, but not in peripheral tissues. All PDE4 inhibitors tested were potent competitors for [3H]piclamilast binding; the competition curves for rolipram, desmethylpiclamilast, ICI 63,197, and Ro 20-1724 were better described by a two-site model, while the competition curves for piclamilast, cilomilast, roflumilast, and CDP 840 were adequately described by a one-site model. Inhibitors of other PDE families were much less potent. The inhibition of [3H]piclamilast was further tested in the presence of 1 μM rolipram to isolate the LARBS. Under this condition, the competition curves for all the inhibitors were adequately described by a one-site model, with Kivalues close to that for the LARBS. The results indicated that [3H]piclamilast is a useful tool to directly study inhibitor interaction with the HARBS and the LARBS in rat brain.

Piclamilast is a type 4 phosphodiesterase (PDE4) inhibitor with equal affinity for the high-affinity rolipram binding site (HARBS) and low-affinity rolipram binding site (LARBS). The binding of [(3)H]piclamilast to preparations of rat brain and peripheral tissue was investigated and compared with that of [(3)H]rolipram. [(3)H]piclamilast binding was high-affinity, saturable, reversible, and partially Mg(2+)-dependent. Binding was detected both to membrane and soluble fractions, with K(d) values of 3.1 and 4.5 nM, respectively. The B(max) values for [(3)H]piclamilast were about 1.5-fold greater than that of [(3)H]rolipram binding, suggesting that [(3)H]piclamilast, but not [(3)H]rolipram, binds to LARBS as well as the HARBS. The HARBS was present in all the brain regions examined, but not in peripheral tissues. All PDE4 inhibitors tested were potent competitors for [(3)H]piclamilast binding; the competition curves for rolipram, desmethylpiclamilast, ICI 63,197, and Ro 20-1724 were better described by a two-site model, while the competition curves for piclamilast, cilomilast, roflumilast, and CDP 840 were adequately described by a one-site model. Inhibitors of other PDE families were much less potent. The inhibition of [(3)H]piclamilast was further tested in the presence of 1 microM rolipram to isolate the LARBS. Under this condition, the competition curves for all the inhibitors were adequately described by a one-site model, with K(i) values close to that for the LARBS. The results indicated that [(3)H]piclamilast is a useful tool to directly study inhibitor interaction with the HARBS and the LARBS in rat brain.

The effects of chronic exposures (nine, 48 h apart) of conscious guinea pigs to lipopolysaccharide (LPS) (30 μg · ml−1, 1 h) on airway function, airway histology (in particular, goblet cell numbers), and inflammatory cell infiltration of the lungs were examined as a model of chronic inflammatory lung disease, such as chronic obstructive pulmonary disease. The sensitivity of these parameters to treatment with the corticosteroid, dexamethasone, or the phosphodiesterase-4 (PDE4) inhibitor, rolipram, was determined. As the number of LPS exposures increased, there was a progressively persistent bronchoconstriction after each exposure. After nine LPS exposures, there was evidence on histological examination of airway infiltration of, predominantly, neutrophils in perivascular, peribronchial, and alveolar tissues. After chronic LPS exposure, the airway epithelium possessed a marked goblet cell hyperplasia and evidence of inflammatory edema, features contributory to reduced airway caliber. Treatment with dexamethasone (20 mg · kg−1) or rolipram (1 mg · kg−1), administered (i.p.) 24 and 0.5 h before exposure and 24 and 47 h after each subsequent exposure, attenuated the inflammatory cell infiltration into the airway, goblet cell hyperplasia, and inflammatory edema. Dexamethasone exacerbated, whereas rolipram reversed, the chronic LPS-induced bronchoconstrictions. This study demonstrates that chronic LPS causes persistent bronchoconstriction, neutrophilic airway inflammation, goblet cell hyperplasia, and edema. These rolipram-sensitive features suggest the potential of PDE4 inhibitors in chronic inflammatory lung diseases.

The effects of chronic exposures (nine, 48 h apart) of conscious guinea pigs to lipopolysaccharide (LPS) (30 microg. ml(-1), 1 h) on airway function, airway histology (in particular, goblet cell numbers), and inflammatory cell infiltration of the lungs were examined as a model of chronic inflammatory lung disease, such as chronic obstructive pulmonary disease. The sensitivity of these parameters to treatment with the corticosteroid, dexamethasone, or the phosphodiesterase-4 (PDE4) inhibitor, rolipram, was determined. As the number of LPS exposures increased, there was a progressively persistent bronchoconstriction after each exposure. After nine LPS exposures, there was evidence on histological examination of airway infiltration of, predominantly, neutrophils in perivascular, peribronchial, and alveolar tissues. After chronic LPS exposure, the airway epithelium possessed a marked goblet cell hyperplasia and evidence of inflammatory edema, features contributory to reduced airway caliber. Treatment with dexamethasone (20 mg. kg(-1)) or rolipram (1 mg. kg(-1)), administered (i.p.) 24 and 0.5 h before exposure and 24 and 47 h after each subsequent exposure, attenuated the inflammatory cell infiltration into the airway, goblet cell hyperplasia, and inflammatory edema. Dexamethasone exacerbated, whereas rolipram reversed, the chronic LPS-induced bronchoconstrictions. This study demonstrates that chronic LPS causes persistent bronchoconstriction, neutrophilic airway inflammation, goblet cell hyperplasia, and edema. These rolipram-sensitive features suggest the potential of PDE4 inhibitors in chronic inflammatory lung diseases.

Upregulation of the cAMP/protein kinase A (PKA) pathway has been shown to result in decreased proliferation, increased differentiation, and subsequent apoptosis of malignant glioma cells. Conventional cAMP analogs, however, are difficult to use in a clinical setting. Therefore, we investigated the effects of rolipram, a drug that has undergone clinical trials as an antidepressant and has also been proposed as a treatment for multiple sclerosis. Rolipram acts as a specific inhibitor of type IV phosphodiesterase (PDE4), leading to increased intracellular levels of cAMP. We report that the inhibition of PDE4 by rolipram results in the activation of the cAMP/PKA pathway, with potent stimulation of a reporter gene containing a cAMP-responsive element in its promoter region. Further, treatment of the human glioma cell line A-172 with rolipram results in increased expression of the cell cycle inhibitors p21Cip1 and p27Kip1, and decreased activity of cdk2, a cyclin-dependent kinase essential for cell cycle progression. As a result, the proliferation of A-172 cells is inhibited, with induction of a G1 block. Eventually, rolipram-treated A-172 cells undergo differentiation, which is followed by apoptotic cell death. As we observe this effect with other glioma cell cultures as well, our results suggest that rolipram could prove useful as a novel differentiating agent with both cytostatic and cytotoxic potential in the treatment of malignant gliomas.

This study investigated whether a correlation between airway hyperreactivity (AHR), leukocyte influx, and nitric oxide (NO) existed in guinea pigs chronically exposed to lipopolysaccharide (LPS). The effect of the corticosteroid, dexamethasone, or phosphodiesterase-4 (PDE4) inhibitor, rolipram, on these features was studied. Airway function was measured in conscious guinea pigs (specific airways conductance) before and after single, double, or chronic (nine) LPS (30 μg · ml−1, 1 h) exposures. Airway reactivity to inhaled histamine (1 mM, 20 s) was assessed before and at various times after LPS challenges. Leukocytes and NO metabolites were measured in bronchoalveolar lavage fluid (BALF). AHR occurred at 1 h after a single LPS challenge and was resolved by 4 h. This coincided with reduction and recovery, respectively, of BALF NO levels. The AHR and NO deficiency were extended to 4 h, after a double LPS exposure. Chronic LPS exposures, 48 h apart, initially caused persistent bronchodilations, whereas later exposures produced progressively persistent bronchoconstrictions. There was AHR 24 h after the eighth challenge. Twenty-four hours after the ninth LPS exposure, macrophages, neutrophils, eosinophils, and NO metabolites were elevated in BALF. Dexamethasone (20 mg · kg−1i.p.) or rolipram (1 mg · kg−1i.p.) prevented single and chronic LPS-induced AHR, the respective deficiency and elevation in NO metabolites, and the chronic LPS-induced leukocyte influx. Dexamethasone exacerbated, whereas rolipram reversed, the chronic LPS-induced bronchoconstrictions. This study demonstrates for the first time that chronic LPS causes persistent bronchoconstriction, neutrophilic inflammation, AHR, and NO overproduction in guinea pig airways. These rolipram-sensitive features suggest the potential of PDE4 inhibitors in airway disease.

This study investigated whether a correlation between airway hyperreactivity (AHR), leukocyte influx, and nitric oxide (NO) existed in guinea pigs chronically exposed to lipopolysaccharide (LPS). The effect of the corticosteroid, dexamethasone, or phosphodiesterase-4 (PDE4) inhibitor, rolipram, on these features was studied. Airway function was measured in conscious guinea pigs (specific airways conductance) before and after single, double, or chronic (nine) LPS (30 microg x ml(-1), 1 h) exposures. Airway reactivity to inhaled histamine (1 mM, 20 s) was assessed before and at various times after LPS challenges. Leukocytes and NO metabolites were measured in bronchoalveolar lavage fluid (BALF). AHR occurred at 1 h after a single LPS challenge and was resolved by 4 h. This coincided with reduction and recovery, respectively, of BALF NO levels. The AHR and NO deficiency were extended to 4 h, after a double LPS exposure. Chronic LPS exposures, 48 h apart, initially caused persistent bronchodilations, whereas later exposures produced progressively persistent bronchoconstrictions. There was AHR 24 h after the eighth challenge. Twenty-four hours after the ninth LPS exposure, macrophages, neutrophils, eosinophils, and NO metabolites were elevated in BALF. Dexamethasone (20 mg x kg(-1) i.p.) or rolipram (1 mg x kg(-1) i.p.) prevented single and chronic LPS-induced AHR, the respective deficiency and elevation in NO metabolites, and the chronic LPS-induced leukocyte influx. Dexamethasone exacerbated, whereas rolipram reversed, the chronic LPS-induced bronchoconstrictions. This study demonstrates for the first time that chronic LPS causes persistent bronchoconstriction, neutrophilic inflammation, AHR, and NO overproduction in guinea pig airways. These rolipram-sensitive features suggest the potential of PDE4 inhibitors in airway disease.

Proinflammatory cytokines are supposed to be involved in the pathophysiology of neuronal damage following excitotoxic lesions. We examined the effect of rolipram, a TNF-α-inhibitor, on excitotoxic neuronal damage. Quinolinic acid (240 nmol in 1 μl) was injected stereotactically into the striatum of male Wistar rats. Four groups of QA rats were treated i.p. with solvent, MK-801 (4 mg/kg) or rolipram (0.3 mg/kg) which was started either 6 or 24 h after QA injection and continued with daily applications for 14 days. QA injection induced neuronal damage which affected 93 of the striatal area. MK-801 reduced this damage to 12 of the striatal area. Treatment with rolipram when started at 6 h after QA injection resulted in neuronal damage amounting to 60; the result after starting at 24 h was not different from solvent (91). The present results demonstrate that rolipram reduces neuronal damage induced by intrastriatal QA application.

The high affinity and selective cAMP-specific phosphodiesterase-4 inhibitors Ro 20-1724, R-, R/S- and S-rolipram were labeled with ¹¹C by O-[¹¹C]methylation of their respective phenolic precursors using [¹¹C]methyl iodide. The desmethyl precursor of Ro 20-1724 was prepared by selective dealkylation with iodotrimethylsilane, whereas, dealkylation of racemic rolipram was not selective and yielded several products. Enantiomeric separation of R- and S-desmethylrolipram was carried out by chiral semi-preparative high performance liquid chromatography. The final ¹¹C-labeled products were prepared in high radiochemical purity (>99%), yields (45-75%, decay-corrected) and specific activities [18.5-92.5 GBq/µmol], within 30 min from end-of-bombardment. Copyright © 2001 John Wiley & Sons, Ltd.

In this study, we examined whether morphine dependence was inhibited by rolipram, a cyclic AMP selective phosphodiesterase inhibitor in mice, since a role for the cyclic AMP systems in the development of morphine dependence has been reported.Mice, which received morphine (10 mg kg−1s.c.) twice a day for 5 days showed withdrawal syndromes such as jumping, rearing and forepaw tremor following naloxone challenge (5 mg kg−1i.p.) on the 6th day.Such mice exhibited a significant elevation of cyclic AMP levels in the thalamus compared to control mice. However, co‐administration of rolipram (1 mg kg−1i.p.) with morphine for 5 days significantly attenuated the severity of the withdrawal syndrome and the increase in the cyclic AMP levels after the administration of naloxone.In naïve mice, acute morphine treatment (10 mg kg−1s.c.) decreased cyclic AMP levels in the thalamus and cerebral cortex 10 min later. The decrease of cyclic AMP levels induced by acute morphine treatment was blocked by co‐administration of rolipram (1 mg kg−1i.p.). However, acute rolipram did not affect the naloxone‐precipitated morphine withdrawal syndrome.These results suggest that the elevation of the cyclic AMP levels is involved in the development of morphine withdrawal syndrome and that blockade of the morphine‐induced reduction of cyclic AMP levels by chronic rolipram inhibits the development of dependence and the behavioural and biochemical changes induced by naloxone. Furthermore, rolipram may be a useful drug for attenuating the development of morphine dependence.

1 In this study, we examined whether morphine dependence was inhibited by rolipram, a cyclic AMP selective phosphodiesterase inhibitor in mice, since a role for the cyclic AMP systems in the development of morphine dependence has been reported. 2 Mice, which received morphine (10 mg kg−1 s.c.) twice a day for 5 days showed withdrawal syndromes such as jumping, rearing and forepaw tremor following naloxone challenge (5 mg kg−1 i.p.) on the 6th day. 3 Such mice exhibited a significant elevation of cyclic AMP levels in the thalamus compared to control mice. However, co-administration of rolipram (1 mg kg−1 i.p.) with morphine for 5 days significantly attenuated the severity of the withdrawal syndrome and the increase in the cyclic AMP levels after the administration of naloxone. 4 In naïve mice, acute morphine treatment (10 mg kg−1 s.c.) decreased cyclic AMP levels in the thalamus and cerebral cortex 10 min later. The decrease of cyclic AMP levels induced by acute morphine treatment was blocked by co-administration of rolipram (1 mg kg−1 i.p.). However, acute rolipram did not affect the naloxone-precipitated morphine withdrawal syndrome. 5 These results suggest that the elevation of the cyclic AMP levels is involved in the development of morphine withdrawal syndrome and that blockade of the morphine-induced reduction of cyclic AMP levels by chronic rolipram inhibits the development of dependence and the behavioural and biochemical changes induced by naloxone. Furthermore, rolipram may be a useful drug for attenuating the development of morphine dependence. British Journal of Pharmacology (2001) 132, 1111 – 1117

Using a rat model of lipopolysaccharide (LPS)-induced pulmonary inflammation, the antiinflammatory activity of SB 207499 was evaluated and compared to that of the prototypic type-4 phosphodiesterase (PDE4) inhibitor, rolipram. In dose–response experiments, we found that rats exposed to 10 μg or 100 μg of intratracheal (it) LPS developed a prominent pulmonary inflammation, due to a significant increase in the number of recoverable bronchoalveolar lavage neutrophils. The pulmonary neutrophilia, provoked by the challenge of 10 μg LPS/rat, was significant at 2 h, peaked by 16 h, declined thereafter but remained elevated for up to 48 h. Additionally, the exposure of rats to 10 μg LPS caused the local pulmonary production of TNF- α. In contrast to the cellular influx, TNF- αproduction peaked at 2 h and rapidly declined to negligible levels by 8 h. While low levels were detected, the levels of IL-1 βin bronchoalveolar lavage did not significantly differ from saline challenged animals. Rats pretreated with rolipram or SB 207499, displayed dose-dependent inhibition of the LPS-induced pulmonary inflammation. Nevertheless, the pulmonary production of TNF- αand IL-1βwas unaffected by either SB 207499 or rolipram. When provoked with the 10 μg dose of LPS, adrenalectomized rats produced a similar 24 h induction of pulmonary neutrophilia. Pretreatment of adrenalectomized rats with the PDE4 inhibitors showed similar inhibitory results to those obtained in normal rats. In summary, we have shown, using a rat model of LPS-induced pulmonary neutrophilic inflammation, that the inhibitory activities of rolipram or SB207499 are not linked to the production of TNF-αor the inhibition of IL-1 β, and occur independently of endogenous catecholamine or corticosteroid release.