Skip to main content
. 2014 Jul 28;9(7):e103118. doi: 10.1371/journal.pone.0103118

Figure 3. H. procumbens root extract specifically activates GHS-R1a receptor independent of harpagoside.

Figure 3

Calcium mobilization upon exposure to H. procumbens root extract and harpagoside in Hek cells stably expressing the GHS-R1a receptor as an EGFP fusion protein. H. procumbens root extract induced GHS-R1a receptor activation was enhancedfollowing attenuation of constitutive receptor activity by pre-treatment with the GHS-R1a receptor inverse agonist, [D-Arg1, D-Phe5, D-Trp7,9, Leu11]-substance P (500 nM, SP-analogue) (A). The iridoid glycoside harpagoside, one of the main compounds present in H. procumbens, did not show an enhanced GHS-R1a receptor-mediated calcium influx, suggesting that the activity observed in this extract is due to others compounds present (B). Graph represents the mean ± SEM of a representative experiment from three (A) or two (B) independents experiments with each concentration point performed in triplicate. Intracellular calcium increase was depicted as a percentage of maximal calcium increase as elicited by control (3.3% FBS). ***p<0.001, **p<0.01 compared with no [D-Arg1, D-Phe5, D-Trp7,9, Leu11]-substance P pre-treatment.