EN
Changes in NGF release during stressful events have been associated with the activation of neurons expressing NGF receptors. This study examined the influence of acute stress-induced stimulation on NGF/c-Fos colocalization in the following limbic regions: the paraventricular (PV) nucleus of the hypothalamus, medial (MeA) nucleus of the amygdala, and CA3 hippocampus. Juvenile (P21) and aged rats (P360) were exposed to a 15-minute acute open field (OF) test. Double immunofluorescence staining, used to detect NGF-ir and c-Fos-ir cells, revealed a higher percentage of NGF/c-Fos-ir neurons in the P21 control group than in the P360 control group. Under OF acute stimulation, a statistically significant (p < 0.05) increase of NGF/c-Fos level in CA3 of juvenile animals and in PV and CA3 of the aged rats was observed. These observations indicate that the investigated structures in both age groups show a different response to acute OF stimulation. Acute OF affects the levels of NGF/c-Fos more significantly in aged rats. (Folia Morphol 2009; 68, 3: 129–134)