Fig. 5

Effect of the second LPS injection on IL-1β immunoreactivity in the SFO. Cryosections were immunostained with antibodies against LPS, the myeloid lineage cell marker Iba1, and the outer basement membrane marker laminin-111. a Immunoreactivity of LPS was found in the SFO perivascular space 1 h after the second dose of LPS injection of vehicle- and LPS-pre-injected mice. b Immunohistochemistry showed that IL-1β expression was predominantly observed in the Iba1⁺ perivascular macrophages inside (arrows) or spanning (arrowheads) the laminin-111⁺ outer basement membrane following the second LPS injection 4 days after the first vehicle injection (vehicle-4 days-LPS) and 2 days after the first LPS injection (LPS-2 days-LPS). In contrast, following the second LPS injection 4 days after the first LPS injection (LPS-4 days-LPS), IL-1β immunoreactivity was rarely found in the Iba1⁺ perivascular macrophages of mice injected with LPS for the first dose. c Quantitative analysis revealing the effects of second LPS injection 4 days after the first vehicle or LPS injection on the number of IL-1β⁺ Iba1⁺ cells in the SFO of adult mice. N = 4. *P < 0.05, determined by Student’s t test. Laminin, laminin-111; N.D., not detected; p, parenchymal area; v, vasculature. Scale bars are 10 μm