Abstract
Bladder pain is frequently associated with bladder inflammation, as in conditions like interstitial cystitis (IC), for which current analgesic therapies have limited efficacy. The antinociceptive effect of alpha-2-delta (α2δ) ligands on inflammation-associated visceral pain like that experienced in cystitis has been poorly investigated. To investigate the effect of pregabalin (PGB), an α2δ ligand, we evaluated its impact on mechanical hyperalgesia in a mouse model of cystitis induced by cyclophosphamide (CYP). We further studied its effect on inflammation and NF-kB pathway activation. Acute cystitis was induced by intraperitoneal injection of 150 mg kg-1 of CYP in C57Bl/6J male mice. PGB was subcutaneously injected (30 mg kg-1) 3 h after CYP injection. The effect of PGB on CYP-induced mechanical referred hyperalgesia (abdominal Von Frey test), inflammation (organ weight, cytokine production, α2δ subunit level, NF-kB pathway activation) were assessed 1 h after its injection. In parallel, its effect on cytokine production, α2δ subunit level and NF-kB pathway activation was assessed in vitro on peritoneal exudate cells (PECs) stimulated with LPS. PGB treatment decreased mechanical referred hyperalgesia. Interestingly, it had an anti-inflammatory effect in the cystitis model by reducing pro-inflammatory cytokine production. PGB also inhibited NF-kB pathway activation in the cystitis model and in macrophages stimulated with LPS, in which it blocked the increase in intracellular calcium. This study shows the efficacy of PGB in hypersensitivity and inflammation associated with cystitis. It is therefore of great interest in assessing the benefit of α2δ ligands in patients suffering from cystitis.
Highlights
Bladder pain is frequently associated with bladder inflammation, as in interstitial cystitis (IC) (Ogawa et al, 2015)
Two abdominals lavage were successively realized with 5 ml of PBS+0.5% of fetal bovine serum (FBS)
PGB has a better affinity for these units than GBP, another α2δ ligand (Taylor, 2009) several findings suggest an involvement of these subunits in the context of visceral pain at a peripheral level in intestinal primary afferent fibers (Needham et al, 2010), or at a central level (Liao et al, 2010)
Summary
Bladder pain is frequently associated with bladder inflammation, as in interstitial cystitis (IC) (Ogawa et al, 2015). The mechanisms include an increase in mucosal bladder permeability (Buffington and Woodworth, 1997), leading to sensitization of bladder afferent pathways and inflammation (Yoshimura et al, 2002), and sensitization of peripheral and/or central pain pathways (Ogawa et al, 2015). The efficacy of anti-nerve growth factor (NGF) therapy in humans (Evans et al, 2011) confirms the involvement of NGF in the pathophysiology of bladder pain. All these peripheral mediators can sensitize the mechanosensitive afferent fibers or increase their recruitment (Sengupta and Gebhart, 1994)
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