Adaptor Proteins, Signal Transducing/metabolism; Neurons/physiology; Nitric Oxide Synthase Type I/metabolism; Signal Transduction/physiology; p38 Mitogen-Activated Protein Kinases/metabolism; Adaptor Proteins, Signal Transducing/genetics; Analysis of Variance; Animals; Animals, Newborn; Brain/cytology; Calcium/metabolism; Cell Death/drug effects; Cell Death/physiology; Cells, Cultured; Enzyme Inhibitors/pharmacology; Excitatory Amino Acid Agonists/pharmacology; Green Fluorescent Proteins/genetics; Green Fluorescent Proteins/metabolism; Humans; Hypoxia/pathology; Intracellular Signaling Peptides and Proteins/genetics; Intracellular Signaling Peptides and Proteins/metabolism; L-Lactate Dehydrogenase/metabolism; N-Methylaspartate/pharmacology; Nerve Tissue Proteins/metabolism; Neurons/drug effects; Nitric Oxide Synthase Type I/genetics; Peptides/pharmacology; Protein Conformation; RNA, Small Interfering/pharmacology; Rats; Receptors, N-Methyl-D-Aspartate/metabolism; Signal Transduction/drug effects; Transfection