Figure 1.

Interaction of IL-6 Gene Expression with Sex and Diet in the Parabrachial Nucleus

(A–F) Mice, 5 weeks old at the start of the experiment, were fed a normal chow or a high-fat diet for 8 weeks. Measurements shown were taken at 8 weeks on the respective diet.

(A) Body weight of male mice at 13 weeks of age (n = 10, for all groups).

(B) IL-6 gene expression in male mice in the parabrachial nucleus as detected by qPCR.

(C) Expression of other inflammation-associated genes (n = 8–9) in male mice in the parabrachial nucleus as detected by qPCR.

(D) qPCR of IL-6 expression in other food intake-associated brain regions in male mice, hypothalamus (HYP), amygdala (AMYG), and hippocampus (HIPP) (n = 6–10).

(E) Body weight of female mice at 13 weeks old (n = 10, for all groups).

(F) qPCR of IL-6 and IL-1 gene expression in the parabrachial nucleus of female mice. IL-1 was below the detection threshold.

(G) Body weight of male rats on a high-fat/high-sugar diet (n = 5).

(H) White adipose tissue mass in male rats on a chow or a high fat/high-sugar diet.

(I) IL-6 gene expression, as detected by qPCR, in male rats maintained on a chow or a high-fat/high-sugar diet, 14 weeks on the tissue collection day.

(J and K) Body weight (J) and IL-6 expression (K) in female rats maintained on a chow or a high-fat/high-sugar diet for 14 weeks.

(L–S) IL-6 mRNA is displayed in green, and cell nuclei is displayed in blue (DAPI).

(L) Lateral parabrachial nucleus IL-6 mRNA was detected using fluorescent in situ hybridization (RNAScope).

(M–P) DAPI (M), IL-6 (N), DAPI with IL-6 (O), and a high-resolution image of single cells in the lPBN showing IL-6 and DAPI (P).

(Q–S) To understand the cellular origin of IL-6 in the lPBN, we used RNAScope to co-localize IL-6 mRNA with neuronal (Rbfox3; red; Q), glial (GFAP; orange; R), or microglial (AIF1; gray; S) mRNA markers. Gene expression data were normalized to the housekeeping gene Ppia and are presented as mean ± SEM. PBN, parabrachial nucleus; Il-6, interleukin-6; Il-1, interleukin-1; Il-6r, IL-6 receptor; Tnf-α, tumor necrosis factor alpha; GWAT, gonadal white adipose tissue; IWAT, inguinal white adipose tissue; X, cycle threshold values in real-time PCR were out of the defined threshold point of 40 cycles, indicating that IL-1 levels were too low to be evaluated and compared.

For comparison of male and female IL-6 gene expression, see Figure S1. For results of approximate quantification of co-expression of each of the cellular markers with IL-6 mRNA, see Figure S2. All gene expression presented here as bar graphs was detected by real-time qPCR. Data represent mean ± SEM. ^∗p < 0.05; ^∗∗p < 0.005; ^∗∗∗p < 0.001; compared with respective controls, unpaired Student’s t test comparisons.