Calcium-binding proteins in the dentate gyrus.

Calbindin D28k (CaBP) is present throughout the entire cell volume of all dentate granule cells in the rat and its appearance is a useful indicator of their development and maturation. Kindling induces a dramatic reduction of granule cell CaBP content but does not make granule cells any more susceptible to the effects of ischemia in adult rats. Others have reported that the levels of CaBP are regulated by corticosterone but our results (in adrenalectomized Wistar or hypophysectomized Sprague-Dawley rats) suggest that any effect is small and transitory. Parvalbumin (PV) is located quite specifically within the entire cell volume of a subpopulation of GABAergic neurons both in the granule cell layer and hilar zone. It appears quite late in the development of the neurons. Reports that kindling induces an increase in PV immunoreactivity in neurons within the hippocampal formation are not supported by the direct measurement of PV levels by radioimmunoassay. Hypophysectomy resulted in a significant fall in PV levels in a number of brain areas including the combined dentate gyrus/CA3 region of the hippocampal formation.