Long-lasting changes in the density of nitrergic neurons following kainic acid administration and chronic hypoxia

Using histochemical analysis (NADPH-diaphorase) we have investigated the influence of intraperitoneal administration of kainic acid (KA), hypoxia and combination of both these factors on neurons of the hippocampus and on the primary auditory cortex (PAC) in male rats of the Wistar strain. Kainic acid was administered to 18-day-old animals, which were exposed to long-lasting repeated hypoxia from the 2nd till the 17th day of age in a hypobaric chamber (for 8 hours a day). At the age of 1 year, the animals were transcardially perfused with 4 % paraformaldehyde under deep thiopental anesthesia. Cryostate sections were stained to identify NADPH-diaphorase positive neurons that were then quantified in CA1 and CA3 areas of the hippocampus, in the dentate gyrus and in the PAC. Both, hypoxia and KA lowered the number of NADPH-diaphorase positive neurons in the hilus, dorsal and ventral blades of the dentate gyrus, CA1 and CA3 areas of the hippocampus. On the contrary, KA given to the hypoxic animals increased the number of NADPH-diaphorase positive neurons in the dorsal blade of the dentate gyrus and PAC.