BackgroundActivation of glial cells, including astrocytes and microglia, has been implicated in the inflammatory responses underlying brain injury and neurodegenerative diseases including Alzheimer's and Parkinson's diseases. Although cultured astrocytes and microglia are capable of responding to pro-inflammatory cytokines and lipopolysaccharide (LPS) in the induction and release of inflammatory factors, no detailed analysis has been carried out to compare the induction of iNOS and sPLA2-IIA. In this study, we investigated the effects of cytokines (TNF-alpha, IL-1beta, and IFN-gamma) and LPS + IFN-gamma to induce temporal changes in cell morphology and induction of p-ERK1/2, iNOS and sPLA2-IIA expression in immortalized rat (HAPI) and mouse (BV-2) microglial cells, immortalized rat astrocytes (DITNC), and primary microglia and astrocytes.Methods/ResultsCytokines (TNF-alpha, IL-1beta, and IFN-gamma) and LPS + IFN-gamma induced a time-dependent increase in fine processes (filopodia) in microglial cells but not in astrocytes. Filopodia production was attributed to IFN-gamma and was dependent on ERK1/2 activation. Cytokines induced an early (15 min) and a delayed phase (1 ~ 4 h) increase in p-ERK1/2 expression in microglial cells, and the delayed phase increase corresponded to the increase in filopodia production. In general, microglial cells are more active in responding to cytokines and LPS than astrocytes in the induction of NO. Although IFN-gamma and LPS could individually induce NO, additive production was observed when IFN-gamma was added together with LPS. On the other hand, while TNF-alpha, IL-1beta, and LPS could individually induce sPLA2-IIA mRNA and protein expression, this induction process does not require IFN-gamma. Interestingly, neither rat immortalized nor primary microglial cells were capable of responding to cytokines and LPS in the induction of sPLA2-IIA expression.ConclusionThese results demonstrated the utility of BV-2 and HAPI cells as models for investigation on cytokine and LPS induction of iNOS, and DITNC astrocytes for induction of sPLA2-IIA. In addition, results further demonstrated that cytokine-induced sPLA2-IIA is attributed mainly to astrocytes and not microglial cells.

Great apes can perceive images as representative of corresponding real-life objects. Coupled with the potential advantages of identifying specific members of one's species and mounting evidence for individual recognition in other non-humans, it seems likely that great apes would have the ability to identify conspecifics in photographs. The ability of four orangutans and a gorilla to match images of individuals of their own and a closely related but unfamiliar species was examined here for the first time. First, the subjects matched photographs of familiar conspecifics taken at various time points in a delayed matching-to-sample procedure (Experiment 1). Second, they matched different photographs of unfamiliar individuals of a different species (Experiment 2) at above chance levels. These results suggest that the subjects matched photographs by matching physical features, not necessarily by recognizing the identity of the individuals depicted. However, they also quickly learned to select photographs of familiar individuals when these photographs were paired with photographs of unfamiliar individuals of their own species (Experiment 3), and three subjects showed transfer to novel images of familiar and unfamiliar individuals. Thus, the findings support the idea that subjects attended to physical features to identify individuals that they could categorize on the basis of familiarity.

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