Differences in phosphodiesterase 3A and 3B expression after ischemic insult.

Phosphodiesterase (PDE) exists in the cardiovascular system, adipose tissue and platelets, and its inhibition increases the cellular levels of cAMP, which could activate cAMP-responsive element binding protein (pCREB). The present study was designed to map the expression of PDE3A/B in the forebrain and define the time course of PDE3 expression in the ischemic boundary zone after ischemia. The number of PDE3A-positive cells (neurons and endothelial cells) remained unchanged, while PDE3B-positive cells gradually increased after ischemia/reperfusion. In the corpus callosum, PDE3B was expressed in oligodendrocytes, oligodendrocyte progenitor cells, and astrocytes. PDE3B-expressing astrocytes showed gradual increase after ischemia/reperfusion. In the cortex, the majority of PDE3B-expressing cells before ischemia were neurons, though few were astrocytes. Ischemic insult resulted in gradual increase in PDE3B-expressing astrocytes and neurons, with larger increase in astrocytes. Expression of brain derived neurotrophic factor (BDNF) and B-cell leukemia/lymphoma 2 protein (Bcl-2) was detected in pCREB-positive cells, not in PDE3B-positive cells. Our results demonstrated that ischemic insult increased PDE3B expression, but not PDE3A, and changed the number and type of cells in a time-dependent manner. The variation of PDE3B-expression in the brain might play a crucial pathophysiological role, and regulation of PDE3B production might protect against ischemic brain damage.