[Recent progress in cyclic nucleotide phosphodiesterase research: isozymes, functions, and inhibitors]

Apremilast reversed carfilzomib-induced cardiotoxicity through inhibition of oxidative stress, NF-κB and MAPK signaling in rats

Carfilzomib (CFZ), is a potent, selective second generation proteasome inhibitor, used for the treatment of multiple myeloma. The aim of the present study was to investigate the possible protective effect of apremilast (AP) on the CFZ -induced cardiotoxicity. Rats were randomly divided into four groups: Group 1, served as the control group, received normal saline. Group 2, served as the toxic group, received CFZ (4 mg/kg, intraperitoneally [i.p.]). Groups 3 and 4, served as treatment groups, and received CFZ with concomitant oral administration of AP in doses of 10 and 20 mg/kg/day, respectively. In the present study, administration of CFZ resulted in a significant increase in serum aspartate transaminase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) and creatine kinase-MB (CK-MB), which were reversed by treatment with AP. CFZ resulted in a significant increase in heart malondialdehyde (MDA) contents and decrease in cardiac glutathione (GSH) level and catalase (CAT) enzyme activity which were significantly reversed by treatment with AP. Induction of cardiotoxicity by CFZ significantly increased caspase-3 enzyme activity which were reversed by treatment with AP. RT-PCR analysis revealed an increased mRNA expression of NF-κB, ERK and JNK which were reversed by treatment with AP in cardiac tissues. Western blot analysis revealed an increased expression of caspase-3 and NF-κB p65 and a decrease expression of inhibitory kappa B-alpha (Iκbα) with CFZ, which were reversed by treatment with AP. In conclusion, apremilast showed protective effect against CFZ-induced cardiotoxicity.

Effects of tetrandrine on cAMP and cGMP levels in rabbit corpus cavernosum in vitro

The aim of this study was to further investigate the relaxation mechanism of tetrandrine (Tet), a bis-benzylisoquinoline alkaloid isolated from the Chinese medicinal herb-root of Stephania tetrandra S Moore, on rabbit corpus cavernosum tissue in vitro. The effects of Tet on the concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in isolated and incubated rabbit corpus cavernosum tissue were recorded by means of (125)I radioimmunoassay. The basal concentration of cAMP in corpus cavernosum tissue was 5.67 +/- 0.97 pmol mg(-1). Tet increased the cAMP concentration in a dose-dependent manner (p < 0.05), but this effect was not inhibited by an adenylate cyclase inhibitor (cis-N-(2-phenylcyclopentyl)azacyclotridec-1-en-2-amine, MDL-12, 330A) (p > 0.05). The accumulation of cAMP induced by prostaglandin E(1) (PGE(1), a stimulator of cAMP production) was also augmented by Tet in a dose-dependent manner (p < 0.05). The basal concentration of cGMP in corpus cavernosum tissue is 0.44 +/- 0.09 pmol mg(-1). Tet did not affect this concentration of cGMP, neither in the presence nor the absence of a guanyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ) (p > 0.05). Further, sodium nitroprusside (SNP, a stimulator of cGMP production)-induced cGMP production was not enhanced by Tet (p > 0.05). Tet, with its relaxation mechanism, can enhance the concentration of cAMP in rabbit corpus cavernosum tissue, probably by inhibiting PDEs activity.

A review of the herbal phosphodiesterase inhibitors; future perspective of new drugs

Phosphodiesterase inhibitors (PDEIs) are a class of drugs that are widely used because of their various pharmacological properties including cardiotonic, vasodilator, smooth muscle relaxant, antidepressant, antithrombotic, bronchodilator, antiinflammatory and enhancer of cognitive function. In the recent years, interest in drugs of plant origin has been progressively increased. Some pharmacologically active substances that come from plants demonstrate PDEI activity. They mainly belong to alkaloids, flavonoids, and saponins. In this review, studies on herbal PDEI were reviewed and their possible therapeutic applications were discussed. Screening plants for PDE inhibitory activity may help to develop standardized phytotherapeutic products or find new sources for new lead structures with PDEI pharmacological activity. The studies discussed in this paper are mainly in vitro and for more reasonable and conclusive results, it is required to conduct in vivo and finally human and clinical tests.

Effects of plant extract neferine on cyclic adenosine monophosphate and cyclic guanosine monophosphate levels in rabbit corpus cavernosum in vitro

AIM

To further investigate the relaxation mechanism of neferine (Nef), a bis-benzylisoquinoline alkaloid extracted (isolated) from the green seed embryo of Nelumbo nucifera Gaertn in China, on rabbit corpus cavernosum tissue in vitro.

METHODS

The effects of Nef on the concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in isolated and incubated rabbit corpus cavernosum tissue were recorded using 125I radioimmunoassay.

RESULTS

The basal concentration of cAMP in corpus cavernosum tissue was 5.67 +/- 0.97 pmol/mg. Nef increased the cAMP concentration in a dose-dependent manner (P < 0.05), but this effect was not inhibited by an adenylate cyclase inhibitor (cis-N-[2-phenylcyclopentyl]azacyclotridec-1-en-2-amine, MDL-12, 330A) (P > 0.05). The accumulation of cAMP induced by prostaglandin E1 (PGE1, a stimulator of cAMP production) was also augmented by Nef in a dose-dependent manner (P < 0.05). The basal concentration of cGMP in corpus cavernosum tissue is 0.44 +/- 0.09 pmol/mg. Nef did not affect this concentration of cGMP, either in the presence or in the absence of a guanyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ) (P > 0.05). Also, sodium nitroprusside (SNP, a stimulator of cGMP production)-induced cGMP production was not enhanced by Nef (P > 0.05).

CONCLUSION

Nef, with its relaxation mechanism, can enhance the concentration of cAMP in rabbit corpus cavernosum tissue, probably by inhibiting phosphodiesterase activity.