Fig. 5

Relative gene expression of IL-1β mRNA in the spinal cord, ventrolateral periaqueductal gray, and hippocampus of male and female rats treated with lipopolysaccharide (100 μg/kg). Male and female rats were treated with either minocycline (one 50 mg/kg dose and second 25 mg/kg dose administered 12 h apart) or water and 1 h after that with either 100 μg/kg of lipopolysaccharide (LPS) or sterile saline (1 ml/kg) intraperitoneal (n = 8/group). Four hours later, the spinal cord, ventrolateral periaqueductal gray (vlPAG), and hippocampus were dissected for analysis of IL-1β mRNA expression. Graphs represent the mean ± SEM. Different asterisk combinations (e.g., * vs. ** vs. ***) represent significantly different groups. Thus, similar asterisk combinations are not significantly different from each other. a LPS significantly increased the production of IL-1β in the spinal cord of both males and females but to a greater extent in males than in females (sex × LPS interaction: F _1,62 = 7.48; p = 0.008). Minocycline significantly attenuated the increase in LPS in both males and females (minocycline × LPS interaction: F _1,62 = 11.21; p = 0.001). We found no significant interaction of minocycline and sex (p = 0.263). b We found similar effects of LPS and minocycline treatment on IL-1β expression in the vlPAG (sex × LPS interaction: F _1,62 = 8.17; p = 0.006; minocycline × LPS interaction: F _1,62 = 4.63; p = 0.037). c LPS significantly and similarly increased IL-1β in the hippocampus of both males and females (main effect of LPS: F _1,62 = 18.47; p < 0.001; minocycline × LPS: F _1,62 = 3.32; p = 0.072)