Biphalin, a Dimeric Enkephalin, Alleviates LPS-Induced Activation in Rat Primary Microglial Cultures in Opioid Receptor-Dependent and Receptor-Independent Manners

Figure 4

The influence of biphalin on NF-κB (a) and IκB (b) phosphorylation and iNOS (c), IL-1β (d), IL-18 (e), COX-2 (f), and NLRP3 (g) protein levels in vehicle- and LPS-treated primary microglial cells. Microglial cells were treated with biphalin (BIPH; 10 μM) for 30 min and then with LPS (100 ng/mL) for 1 h (a, b) or 24 h (c, d, e, f, g). Naloxone (NLX; 0.1 μM) was added 30 min before biphalin. The data are presented as the fold change compared with the control group (vehicle-treated cells) as the mean ± SEM of 3–6 independent experiments. The results were statistically evaluated using one-way analysis of variance (ANOVA) followed by Bonferroni’s post hoc test to assess the differences between the treatment groups. Significant differences in comparison with those of the control group (vehicle-treated cells) are indicated by , , , and ; differences between LPS-treated and biphalin- or biphalin- and naloxone-treated cells are indicated by ^#, ^##, and ^###; differences between biphalin-treated and biphalin- and naloxone-treated cells are indicated by ^$.

(a)

(b)

(c)

(d)

(e)

(f)

(g)