Hippocampal interleukin-1β in the juvenile and middle-aged rat: Response to chronic forced swim or high-light open-field stress stimulation

摘要

It is postulated that stress differentially affects interleukin-1β (IL-1β) during ontogenetic life. This study examined the influence of chronic exposure to forced swim (FS) stress or high-light open-field (HL-OF) stress on interleukin-1β (IL-1β). The total level of IL-1β protein was assessed by Western blot analysis of hippocampal extracts. Double immunofluorescence staining was used to reveal the percentage of IL-1β/NeuN (NeuN - neuronal marker) cells in the CA1, CA3 and dentate gyrus (DG) hippocampal subfields. Juvenile (P28; P - postnatal day) and middle-aged (P360) rats were used in the experiment. The research showed no significant differences in IL-1β protein levels between P28 and P360 non-stress rats. However, a substantial increase in the percentage of IL-1β-ir neurons in the CA1, CA3 and DG in P360 rats was observed. Chronic FS had no significant influence on IL-1β expression in the hippocampus or on the percentage of IL-1β-ir neurons in CA1, CA3 and DG hippocampal subfields in either age group. During HL-OF, the IL-1β level was significantly increased in the hippocampus of P28 and P360 rats, whereas a marked increase in the percentage of IL-1β-ir neurons in the CA1, CA3 and DG hippocampal areas occurred only in P360 animals. These results indicate that chronic HL-OF stimulation was the factor inducing changes in the IL-1β protein levels in P28 and P360 rats and in the percentage of IL-1β/NeuN-ir cells in the hippocampus of P360 animals.