Abstract
Adipocyte lipolysis is dependent on an increase in the intracellular concentration of cAMP. Intracellular phosphodiesterases (PDEs) hydrolyze cAMP and limit stimulation of lipolysis. In the present study, the mRNA expression of PDE4 subtypes and the antilipolytic role of PDE4 in rat adipocytes were investigated. Fragments encoding PDE4A (233 bp), PDE4B (786 bp), PDE4C (539 bp), and PDE4D (262 bp) sequences were amplified by RT-PCR. The mRNA expression of PDE4 subtypes (A, B, C, D) determined by real-time quantitative PCR was 7, 18.7, 18.9, and 7.2% relative to PDE3B. Inhibition of PDE4 by rolipram increased basal lipolysis and reversed in part prostaglandin E2 antilipolysis. The combination of PDE3 and PDE4 inhibitors synergistically reversed both prostaglandin E2 and phenylisopropyl adenosine antilipolysis. Stimulation of adipocytes with prostaglandin E2 increased total PDE activity and PDE3 activity measured by hydrolysis of 3[H]cAMP by the particulate fraction of adipocytes. The present study confirmed that mRNAs for all four PDE4 subtypes were expressed in rat adipocytes, with PDE4B and PDE4C predominant. Moreover, PDE4 not only limits the rate of basal lipolysis but also contributes to prostaglandin E2 antilipolysis in rat adipocytes.
Highlights
Adipocyte lipolysis is dependent on an increase in the intracellular concentration of cyclic adenosine monophosphate (cAMP)
PDE4A5, PDE4B2, PDE4C2, PDE4D3, and PDE4D5 are known to be expressed in 3T3-F442A preadipocytes [11]
We previously reported that ginseng extract, but not insulin, inhibited lipolysis in part by activating PDE4 in rat adipocytes
Summary
Adipocyte lipolysis is dependent on an increase in the intracellular concentration of cAMP. The mRNA expression of PDE4 subtypes and the antilipolytic role of PDE4 in rat adipocytes were investigated. Inhibition of PDE4 by rolipram increased basal lipolysis and reversed in part prostaglandin E2 antilipolysis. The present study confirmed that mRNAs for all four PDE4 subtypes were expressed in rat adipocytes, with PDE4B and PDE4C predominant. PDE4 limits the rate of basal lipolysis and contributes to prostaglandin E2 antilipolysis in rat adipocytes.—Wang, H., and N. We previously reported that ginseng extract, but not insulin, inhibited lipolysis in part by activating PDE4 in rat adipocytes. The purpose of the present study was to determine the gene expression of PDE4 subtypes and investigate whether PDE4 plays an antilipolytic role in rat adipocytes
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