Vapreotide is a NK1R antagonist, with an IC50 of 330 nM.
Vapreotide attenuates the effect of SP on calcium release in a concentration-dependent manner. The concentration required for Vapreotide to completely inhibit the effect of SP is about 100 times higher than that required for the NK1R antagonist aprepitant. The effect of Vapreotide on cell proliferation is mediated primarily by SSTR2. In order to further establish the NK1R antagonist effect of Vapreotide, U373MG cells are pretreated with SSTR2 selective antagonist CYN followed by incubation with Vapreotide and SP stimulation. The results show that pretreatment with CYN does not reverse the inhibitory effect of Vapreotide on SP-stimulated IL-8 mRNA expression. Vapreotide reduces HIV-1 replication in MDM as indicated by limited HIV gag mRNA expression compared to control MDM. In addition, SP treatment (10 μM) reverses Vapreotide inhibition of HIV-1 replication in MDM. This observation indicates that the inhibition of HIV-1 replication by Vapreotide is most likely due to its interaction with NK1R[1].
[1]. Spitsin S et al. Analog of somatostatin vapreotide exhibits biological effects in vitro via interaction with neurokinin-1 receptor. Neuroimmunomodulation. 2013;20(5):247-55.