Figure 6. Functional characteristics of α_1B-D₄ and β₁-D₄ receptor heteromers in pineal gland.

Pineal glands extracted at 9:00 h (A and B) or at 20:00 h (C and D) were treated for 10 min with RO 10-5824 (RO), phenylephrine (Phenyl), or isoproterenol (Iso) at 1 µM concentration alone or in combination. The immunoreactive bands, corresponding to ERK 1/2 (Thr¹⁸³-Tyr¹⁸⁵) (A and C) or Akt (Ser⁴⁷³) (B and D) phosphorylation, of three experiments performed in duplicates were quantified, and values represent the mean ± S.E.M. of the fold increase with respect to basal levels found in untreated pineal glands. Significant differences were calculated by a one-way ANOVA followed by post hoc Bonferroni's tests (**p<0.01 and ***p<0.001, as compared to the basal level. ^# p<0.05 and ^## p<0.01, as compared to the sample treated with phenylephrine; ^$ p<0.05 and ^$$$ p<0.001, as compared to the sample treated with isoproterenol). A representative Western blot is shown at the bottom of each panel.