The Effect of Rosmarinic Acid on Apoptosis and nNOS Immunoreactivity Following Intrahippocampal Kainic Acid Injections in Rats

Kainic Acid (KA) is an ionotropic glutamate receptor agonist. KA can induce neuronal overactivity and excitotoxicity. Rosmarinic Acid (RA) is a natural polyphenolic compound with antioxidant, anti-apoptotic, anti-neurodegenerative, and anti-inflammatory properties. This study aimed to assess the effect of RA on apoptosis, nNOS-positive neurons number, as well as Mitogen-Activated Protein Kinase (MAPK) and Cyclooxygenase-2 (COX-2) immunoreactivity, following intrahippocampal Kainic acid injection in rats. The study rats were randomly assigned to three groups of sham, KA (KA was injected into the right side of the hippocampus) and KA+RA (a dose of 10 mg/kg/day through a gavage needle for one week before KA injection). Then, histopathological changes, including apoptosis [Terminal Deoxynucleotidyl Transferase (TdT) dUTP Nick-End Labeling (TUNEL) assay], nNOS-positive neurons number, as well as COX-2 and MAPK immunoreactivity were evaluated in the hippocampus. In the RA pretreated group, nNOS-positive neurons and TUNEL-positive cells were significantly reduced compared to the KA group (P