Calcium-binding proteins in the hippocampal formation of the guinea pig
Calcium ions (Ca2 ) are known as a second messenger in neurons. However, the concentration of Ca2 should be maintained at an optimal level in view of their high toxicity. Calcium-binding proteins (CaBPs) bind Ca2 with high affi nity. The amount of the CaBPs is age-related and varies during brain development. The aim of this study was to analyze the distribution of CaBPs, parvalbumin (PV) and calbindin D-28k (CB), in the hippocampal formation (the dentate gyrus – DG and hippocampus proper – HP). The studies were carried out on the brains of newborn (P0) and 80-day-old (P80) guinea pigs. Labelling immunofl uorescence was performed on 10 μm-thick frozen sections. PV- and CB-immunoreactive (PV-IR, CB-IR) structures were identifi ed with antibodies against PV (1:2000, code P3088) and CB (1:2000, code C9848). Both studied parts are composed of three cellular layers. In the dentate gyrus, PV-IR cells (elongated and oval-shaped) were labelled in the hilus. In the middle (granular) layer only PV-IR dots surrounding negative cells were observed, whereas in the third (molecular) layer no immunoreactive structures were seen. In the hippocampus proper PV-IR neurons (triangular, piriform and oval-shaped) were found in each sector (CA1–CA3) of the pyramidal layer, the same as in the oriens and molecular layers. CB-IR neurons (oval-shaped, densely arranged) were observed mainly in the granular and pyramidal layers. The distribution of the studied calcium-binding proteins was similar in P0 and P80.