Changes in parvalbumin immunoreactivity in the parietofrontal cortex after transient forebrain ischemia in the mongolian gerbil

We investigated the changes in parvalbumin (PV)-immunoreactive (IR) neurons in the parietofrontal cortex after transient forebrain ischemia. In the sham - operated group, PV-IR neurons were present in all layers of the parietofrontal cortex except layer I. Shortly after ischemia the number of PV-IR neurons in layer II/III first increased, and then declined dramatically 12 h after ischemic insult, followed by a second increase after 2 days. At this time the PV immunoreactivity was very weak and only present in the peripheral neuronal cytoplasm. The reversible increase in the number of PV-IR neurons and in the level of their immunoreactivity could result from a transient ischemia-induced increase in intracellular calcium. This pattern of expression was particularly pronounced in layer II/III of the parietofrontal cortex, suggesting that these neurons are especially susceptible to ischemic insult.