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Effects of phosphodiesterase 4 inhibition on alveolarization and hyperoxia toxicity in newborn rats.

Méhats C, Franco-Montoya ML, Boucherat O, Lopez E, Schmitz T, Zana E, Evain-Brion D, Bourbon J, Delacourt C, Jarreau PH - PLoS ONE (2008)

Bottom Line: The current study was undertaken to determine the effects of the prototypal phosphodiesterase-4 inhibitor rolipram on alveolar development and on hyperoxia-induced lung injury.Under room air, rolipram-treated pups had significant decrease of Radial Alveolar Count.The less complex structure of immature lungs of rolipram-treated pups as compared with diluent-treated pups under room air may be explained by the profound effect of PDE4 inhibition on weight gain that interfered with normal alveolarization.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche médicale U767, Paris, France.

ABSTRACT

Background: Prolonged neonatal exposure to hyperoxia is associated with high mortality, leukocyte influx in airspaces, and impaired alveolarization. Inhibitors of type 4 phosphodiesterases are potent anti-inflammatory drugs now proposed for lung disorders. The current study was undertaken to determine the effects of the prototypal phosphodiesterase-4 inhibitor rolipram on alveolar development and on hyperoxia-induced lung injury.

Methodology/findings: Rat pups were placed under hyperoxia (FiO2>95%) or room air from birth, and received rolipram or its diluent daily until sacrifice. Mortality rate, weight gain and parameters of lung morphometry were recorded on day 10. Differential cell count and cytokine levels in bronchoalveolar lavage and cytokine mRNA levels in whole lung were recorded on day 6. Rolipram diminished weight gain either under air or hyperoxia. Hyperoxia induced huge mortality rate reaching 70% at day 10, which was prevented by rolipram. Leukocyte influx in bronchoalveolar lavage under hyperoxia was significantly diminished by rolipram. Hyperoxia increased transcript and protein levels of IL-6, MCP1, and osteopontin; rolipram inhibited the increase of these proteins. Alveolarization was impaired by hyperoxia and was not restored by rolipram. Under room air, rolipram-treated pups had significant decrease of Radial Alveolar Count.

Conclusions: Although inhibition of phosphodiesterases 4 prevented mortality and lung inflammation induced by hyperoxia, it had no effect on alveolarization impairment, which might be accounted for by the aggressiveness of the model. The less complex structure of immature lungs of rolipram-treated pups as compared with diluent-treated pups under room air may be explained by the profound effect of PDE4 inhibition on weight gain that interfered with normal alveolarization.

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PDE4 activity in whole lung homogenates of rat pups exposed to hyperoxia and treated or not with rolipram.Rat pups exposed to normoxia or hyperoxia from birth and treated with rolipram, (n = 5/group), and their littermate controls treated with diluent alone (n = 6/group) were killed on day 6 of life. Whole lungs were dissected out and homogenized as described in Materials and Methods, and cAMP-PDE activity was measured in the absence or the presence of 10 µM rolipram. Data are expressed as mean±sem. † Significantly different from the air-rolipram group; ‡ significant difference between oxygen-diluent and oxygen-rolipram groups. Upper insert: Western blot of PDE4 proteins in whole lung of rat pups exposed to normoxia or hyperoxia from birth, and either treated with rolipram (+) or receiving the diluent alone (−); pups were killed on day 6 of life. Aliquots of lung homogenates with equivalent protein amount were subjected to 8% SDS-PAGE and immunoblotted with specific anti-PDE4A, PDE4B or PDE4D antibodies. This immunoblot is representative of 3 separate experiments with two different animals/group/experiment, 6 different animals/group. A loading control was performed with a specific anti-beta actin antibody.
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pone-0003445-g004: PDE4 activity in whole lung homogenates of rat pups exposed to hyperoxia and treated or not with rolipram.Rat pups exposed to normoxia or hyperoxia from birth and treated with rolipram, (n = 5/group), and their littermate controls treated with diluent alone (n = 6/group) were killed on day 6 of life. Whole lungs were dissected out and homogenized as described in Materials and Methods, and cAMP-PDE activity was measured in the absence or the presence of 10 µM rolipram. Data are expressed as mean±sem. † Significantly different from the air-rolipram group; ‡ significant difference between oxygen-diluent and oxygen-rolipram groups. Upper insert: Western blot of PDE4 proteins in whole lung of rat pups exposed to normoxia or hyperoxia from birth, and either treated with rolipram (+) or receiving the diluent alone (−); pups were killed on day 6 of life. Aliquots of lung homogenates with equivalent protein amount were subjected to 8% SDS-PAGE and immunoblotted with specific anti-PDE4A, PDE4B or PDE4D antibodies. This immunoblot is representative of 3 separate experiments with two different animals/group/experiment, 6 different animals/group. A loading control was performed with a specific anti-beta actin antibody.

Mentions: On day 6 of life, whole-lung PDE4 activity was significantly different among all groups (p<0.05 by Kruskall-Wallis analysis). PDE4 activity tended to be higher in the O2-diluent group as compared with the air-diluent group, although this did not reach significance (p = 0.08) (Figure 4). Treatment with rolipram had no effect on PDE4 activity in normoxia, whereas it decreased it under hyperoxia (p<0.05). PDE4 family is encoded by four genes designated A through D. Whereas PDE4C is absent from adult lungs, PDE4A, 4B, and PDE4D RNAs are expressed in lungs [16]. Immunoblotting with antibodies raised against PDE4A, PDE4B, and PDE4D proteins evidenced only a slight increase of the immunosignal of a PDE4B band with an apparent molecular weight of 72 kDa (insert in Figure 4).


Effects of phosphodiesterase 4 inhibition on alveolarization and hyperoxia toxicity in newborn rats.

Méhats C, Franco-Montoya ML, Boucherat O, Lopez E, Schmitz T, Zana E, Evain-Brion D, Bourbon J, Delacourt C, Jarreau PH - PLoS ONE (2008)

PDE4 activity in whole lung homogenates of rat pups exposed to hyperoxia and treated or not with rolipram.Rat pups exposed to normoxia or hyperoxia from birth and treated with rolipram, (n = 5/group), and their littermate controls treated with diluent alone (n = 6/group) were killed on day 6 of life. Whole lungs were dissected out and homogenized as described in Materials and Methods, and cAMP-PDE activity was measured in the absence or the presence of 10 µM rolipram. Data are expressed as mean±sem. † Significantly different from the air-rolipram group; ‡ significant difference between oxygen-diluent and oxygen-rolipram groups. Upper insert: Western blot of PDE4 proteins in whole lung of rat pups exposed to normoxia or hyperoxia from birth, and either treated with rolipram (+) or receiving the diluent alone (−); pups were killed on day 6 of life. Aliquots of lung homogenates with equivalent protein amount were subjected to 8% SDS-PAGE and immunoblotted with specific anti-PDE4A, PDE4B or PDE4D antibodies. This immunoblot is representative of 3 separate experiments with two different animals/group/experiment, 6 different animals/group. A loading control was performed with a specific anti-beta actin antibody.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2563688&req=5

pone-0003445-g004: PDE4 activity in whole lung homogenates of rat pups exposed to hyperoxia and treated or not with rolipram.Rat pups exposed to normoxia or hyperoxia from birth and treated with rolipram, (n = 5/group), and their littermate controls treated with diluent alone (n = 6/group) were killed on day 6 of life. Whole lungs were dissected out and homogenized as described in Materials and Methods, and cAMP-PDE activity was measured in the absence or the presence of 10 µM rolipram. Data are expressed as mean±sem. † Significantly different from the air-rolipram group; ‡ significant difference between oxygen-diluent and oxygen-rolipram groups. Upper insert: Western blot of PDE4 proteins in whole lung of rat pups exposed to normoxia or hyperoxia from birth, and either treated with rolipram (+) or receiving the diluent alone (−); pups were killed on day 6 of life. Aliquots of lung homogenates with equivalent protein amount were subjected to 8% SDS-PAGE and immunoblotted with specific anti-PDE4A, PDE4B or PDE4D antibodies. This immunoblot is representative of 3 separate experiments with two different animals/group/experiment, 6 different animals/group. A loading control was performed with a specific anti-beta actin antibody.
Mentions: On day 6 of life, whole-lung PDE4 activity was significantly different among all groups (p<0.05 by Kruskall-Wallis analysis). PDE4 activity tended to be higher in the O2-diluent group as compared with the air-diluent group, although this did not reach significance (p = 0.08) (Figure 4). Treatment with rolipram had no effect on PDE4 activity in normoxia, whereas it decreased it under hyperoxia (p<0.05). PDE4 family is encoded by four genes designated A through D. Whereas PDE4C is absent from adult lungs, PDE4A, 4B, and PDE4D RNAs are expressed in lungs [16]. Immunoblotting with antibodies raised against PDE4A, PDE4B, and PDE4D proteins evidenced only a slight increase of the immunosignal of a PDE4B band with an apparent molecular weight of 72 kDa (insert in Figure 4).

Bottom Line: The current study was undertaken to determine the effects of the prototypal phosphodiesterase-4 inhibitor rolipram on alveolar development and on hyperoxia-induced lung injury.Under room air, rolipram-treated pups had significant decrease of Radial Alveolar Count.The less complex structure of immature lungs of rolipram-treated pups as compared with diluent-treated pups under room air may be explained by the profound effect of PDE4 inhibition on weight gain that interfered with normal alveolarization.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche médicale U767, Paris, France.

ABSTRACT

Background: Prolonged neonatal exposure to hyperoxia is associated with high mortality, leukocyte influx in airspaces, and impaired alveolarization. Inhibitors of type 4 phosphodiesterases are potent anti-inflammatory drugs now proposed for lung disorders. The current study was undertaken to determine the effects of the prototypal phosphodiesterase-4 inhibitor rolipram on alveolar development and on hyperoxia-induced lung injury.

Methodology/findings: Rat pups were placed under hyperoxia (FiO2>95%) or room air from birth, and received rolipram or its diluent daily until sacrifice. Mortality rate, weight gain and parameters of lung morphometry were recorded on day 10. Differential cell count and cytokine levels in bronchoalveolar lavage and cytokine mRNA levels in whole lung were recorded on day 6. Rolipram diminished weight gain either under air or hyperoxia. Hyperoxia induced huge mortality rate reaching 70% at day 10, which was prevented by rolipram. Leukocyte influx in bronchoalveolar lavage under hyperoxia was significantly diminished by rolipram. Hyperoxia increased transcript and protein levels of IL-6, MCP1, and osteopontin; rolipram inhibited the increase of these proteins. Alveolarization was impaired by hyperoxia and was not restored by rolipram. Under room air, rolipram-treated pups had significant decrease of Radial Alveolar Count.

Conclusions: Although inhibition of phosphodiesterases 4 prevented mortality and lung inflammation induced by hyperoxia, it had no effect on alveolarization impairment, which might be accounted for by the aggressiveness of the model. The less complex structure of immature lungs of rolipram-treated pups as compared with diluent-treated pups under room air may be explained by the profound effect of PDE4 inhibition on weight gain that interfered with normal alveolarization.

Show MeSH
Related in: MedlinePlus