Identification and Characterisation of Novel Positive Allosteric Modulators of the Galanin 2 Receptor
Poster Oct 10, 2014
Chronic nerve damage or injury induces alterations in the primary sensory neurons in the dorsal root ganglion (DRG) and their central connections. This leads to the development of spontaneous pain; allodynia (the perception of pain from a normally innocuous stimulus), hyperalgesia (an exaggerated response to any given pain stimulus), and expansion of the receptive pain field. These functional changes can result in the development of chronic neuropathic pain (NP), the most common causes of which are diabetes, alcoholism, and chemotherapy for cancer/HIV.
The physiological effects of galanin are mediated by activation of galanin receptors (GalR1, GalR2 and GalR3) which inhibit adenylyl cyclase. GalR2 in addition, mediates intracellular calcium mobilisation. High levels of endogenous galanin in injured primary afferent neurons activate peripheral GalR2 and leads to a marked reduction in nociceptive responses. Positive allosteric modulators (PAMs) of GalR2 could afford therapeutic advantage including, improved receptor selectivity, retention of physiologically-controlled spatial and temporal response, and self-limiting saturability of effect.
We have configured a functional HTRF IP-1 detection assay (Cisbio) which we used to screen a 100K subset of the MRCT compound library to identify novel activators of the GalR2 receptor. Using CHO cells stably expressing GalR2, inclusion of a submaximal concentration (EC30) of galanin facilitated simultaneous detection of both PAMs and agonists. We will show data relating to assay performance and hit rates, in addition to secondary studies for the deconvolution of agonists and PAMs. We will present hit characterisation of putative PAMs and their analogues.
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