Researchers using siRNA complexed with our i-Fect ™ transfection regent have successfully knocked down ASIC3 Receptors in vivo. This publication joins the growing parade (starting with Luo et al, 2005) that reference successful modulation of receptors involved in pain using siRNA complexes. These studies all share animal behavior studies showing a marked change in response to pain stimuli after treatment.
In this study, Dr. Eric Lingueglia and his team found Peripheral ASIC3 channels are thus essential sensors of acidic pain and integrators of molecular signals produced during inflammation where they contribute to primary hyperalgesia.
Emmanuel Deval, Jacques Noël, Nadège Lay, Abdelkrim Alloui, Sylvie Diochot, Valérie Friend, Martine Jodar, Michel Lazdunski and Eric Lingueglia. ASIC3, a sensor of acidic and primary inflammatory pain. The EMBO Journal advance online publication 16 October 2008; doi: 10.1038/emboj.2008.213
Cy3-labelled siRNA no. 1121 and its corresponding scramble (no. 1121S; GCTCACACTACGCAGAGAT) synthesized by MWG Biotech (Germany) were injected in rats by intrathecal bolus to the lumbar region of the spinal cord once a day for 3 days before the induction of inflammation with CFA. Each 10-ml injection corresponded to 2 mg of siRNA complexed with i-Fect siRNA transfection reagent (Neuromics) at a ratio of 1:4 (w:v) (Luo et al, 2005), following the supplier’s suggested protocol. siRNA uptake in lumbar DRGs
was monitored by fluorescence microscopy on cryostat sections 24 h after a single intrathecal injection.
Here’s a synopsis of results:
Inflammation was produced by CFA injection, which led to primary heat hyperalgesia, and this hyperalgesia was drastically reduced by the ASIC3 blocker APETx2 injected subcutaneously, which only access cutaneous nociceptors. It was also drastically reduced when, before triggering the inflammation state, intrathecal
injections of an siRNA against ASIC3 had induced a knockdown of ASIC3 expression in lumbar DRGs.
I will continue to publish updates.