The impact of murine LRRK2 G2019S transgene overexpression on acute responses to inflammatory challenge.

The most common Parkinson's disease (PD) mutation is the gain-of-function LRRK2 G2019S variant, which has also been linked to inflammatory disease states. Yet, little is known of the role of G2019S in PD related complex behavioral or immune/hormonal processes in response to inflammatory/toxicant challenges. Hence, we characterized the behavioral, neuroendocrine-immune and central monoaminergic responses in G2019S overexpressing mutants following systemic interferon-gamma (IFN-γ) or lipopolysaccharide (LPS) administration. Although LPS markedly (and IFN-γ modestly in some cases) increased cytokine and corticosterone levels, while inducing pronounced sickness and home-cage activity deficits, the G2019S mutation had no effect on these parameters. No differences were observed with regards to brain microglia with the acute LPS injection, regardless of genotype. Nor did the G2019S mutation influence neurotransmitter levels within the medial prefrontal cortex or paraventricular nucleus of the hypothalamus. However, the LRRK2 G2019S transgenic mice did have altered monoamine levels within the striatum and hippocampus. Indeed, G2019S mice had altered basal levels and turnover of dopamine within the striatum, along with changes in hippocampal serotonin and norepinephrine activity in response to LPS and IFN-γ. The present findings suggest the importance of murine G2019S in hippocampal and striatal neurotransmission, but that the transgene didn't appear to be involved in functional behavioral and stress-like hormonal and cytokine changes provoked by inflammatory insults.