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. 2017 Aug 1;158(11):2222–2232. doi: 10.1097/j.pain.0000000000001027

Figure 2.

Figure 2.

Changes in the expression of endocannabinoid receptors CB1, CB2, and GPR55 in the brainstem of the rat during postnatal maturation. (A) TaqMan real-time (RT) PCR analysis of CB1 receptor mRNA in the ventral periaqueductal grey (vPAG) of P10, P21, and P40 rats, no statistically significant changes were observed between the ages. (B) Fluorescent image (×20 magnification) and quantification (C) of CB1 immunoreactivity in the vPAG. White arrows denote CB1-specific terminal staining. The expression of CB1 receptors in the vPAG decreased as the animals aged, as immunoreactivity was highest at P10 (P < 0.0001; 1-way analysis of variance [ANOVA]). TaqMan RT-PCR analysis of CB1 receptors in the rostroventral medulla (RVM) of P10, P21, and P40 rats, no changes were observed between the ages. (E) Fluorescent image (×20 magnification) and quantification (F) of CB1 immunoreactivity in the RVM. White arrows denote CB1-specific terminal staining. The expression of CB1 receptors in the RVM increased as the animals aged (P < 0.01-0.001; 1-way ANOVA) (C and D) N = 3 to 5 animals per age group. CTR, control. Data shown here represent mean ± SEM. **, ***, and **** = P < 0.01, P < 0.001, and P < 0.0001, respectively, between age comparisons, 1-way ANOVA with Bonferroni multiple comparisons.