FIGURE 8.

Co-expression of the 5-HT_2C receptor attenuates GHS-R1a-mediated signaling. Cells stably expressing the GHS-R1a receptor (light gray bars) were transduced with viral vectors expressing the 5-HT_2C receptor (dark gray bars) or the partially edited isoform 5-HT_2C-VSV (hatched bars) and treated with 100 nm ghrl or 100 nm MK0677 and with or without (1 μm) RS10221 exposure. A, intracellular calcium increase was reduced in cells co-expressing the 5-HT_2C receptor, which was rescued after RS102221 treatment. B, the GHS-R1a inverse agonist, peptide [d-Arg¹,d-Phe⁵,d-Trp^7,9,Leu¹¹]-substance P (SP; 1 μm), increased total calcium influx but was not able to restore full GHS-R1a-mediated signaling. Intracellular calcium increase was depicted in RFU as a percentage of maximal calcium increase as elicited by ghrelin or MK0677 response in presence of RS102221. Intracellular calcium increase was depicted as a percentage of maximal calcium increase as elicited by control. The data represent the means ± S.E. of a representative experiment of three independent transductions with each concentration point performed in triplicate. Two-way ANOVA followed by Bonferroni multiple comparison test; statistical significance is notated as follows: ***, p < 0.001; and **, p < 0.01.