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Differential type 4 cAMP-specific phosphodiesterase (PDE4) expression and functional sensitivity to PDE4 inhibitors

Hong Bian1, Ji Zhang, Ping Wu

  • 1Schering-Plough Research Institute, Kenilworth, NJ 07033, USA.

Biochemical Pharmacology
|October 23, 2004
PubMed

Insights

Rats exhibit higher susceptibility to phosphodiesterase 4 (PDE4) inhibitor toxicity due to elevated PDE4 expression. This suggests PDE4 inhibitors may be safer for humans compared to rats and monkeys.

Area of Science:

  • Pharmacology
  • Toxicology
  • Biochemistry

Background:

  • Rats show increased susceptibility to phosphodiesterase 4 (PDE4) inhibitor toxicity.
  • The biochemical basis for this higher susceptibility requires elucidation.

Purpose of the Study:

  • To compare PDE4 expression and functional relevance in rats, monkeys, and humans.
  • To investigate the biochemical mechanisms underlying PDE4 inhibitor toxicity.

Main Methods:

  • Quantified mRNA expression levels of PDE4 subtypes (4A, 4B, 4C, 4D) in relevant tissues and leukocytes.
  • Assessed PDE4 enzyme activity in leukocytes.
  • Evaluated the potency of PDE4 inhibitors (rolipram, SB 207499, SCH 351591) in inhibiting TNF production and phenylephrine-induced contraction.

Main Results:

  • Rats displayed significantly higher PDE4 mRNA expression than humans.
  • Higher PDE4 expression correlated with increased enzyme activity in rat leukocytes.
  • PDE4 inhibitor potency followed the order: rat > monkey > human for inhibiting TNF production and vascular contraction.

Conclusions:

  • Elevated PDE4 expression levels in rats likely contribute to their heightened susceptibility to PDE4 inhibitor toxicity.
  • PDE4 inhibitors may pose a lower safety risk in humans compared to monkeys and rats.

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