Expression of Phosphorylated cAMP Response Element Binding Protein (p-CREB) in Bladder Afferent Pathways in VIP−/− Mice with Cyclophosphamide (CYP)-Induced Cystitis

Abstract

The expression of phosphorylated cAMP response element binding protein (pCREB) in dorsal root ganglia (DRG) with and without CYP-induced cystitis (150 mg/kg, i.p; 48 hr) was determined in VIP −/− and wildtype (WT) mice. p-CREB-immunoreactivity (IR) was determined in bladder (Fastblue) afferent cells. Nerve growth factor (NGF) bladder content was determined by ELISAs. Basal expression of pCREB-IR in DRG of VIP −/− mice was (p ≤ 0.01) greater in L1, L2, L5-S1 DRG compared to WT mice. CYP treatment in WT mice increased (p ≤ 0.05) pCREB-IR in L1, L2, L5-S1 DRG. CYP treatment in VIP −/− mice (p ≤ 0.01) increased (p ≤ 0.01) p-CREB-IR in L6-S1 DRG compared to WT with CYP. In WT mice, bladder afferent cells (20-38%) in DRG expressed pCREB-IR under basal conditions. With CYP, pCREB-IR increased in bladder afferent cells (60-65%; L6-S1 DRG) in WT mice. In VIP −/− mice, bladder afferent cells (12-58%) expressed pCREB-IR under basal conditions and CYP increased pCREB expression (78-84%) in L6-S1 DRG. Urinary bladder NGF expression in VIP −/− mice under basal conditions or after cystitis was significantly greater than WT. Detrusor smooth muscle thickness was significantly increased in VIP −/− mice. Bladder NGF expression may contribute to differences in pCREB expression.

Exaggerated Expression of Inflammatory Mediators in Vasoactive Intestinal Polypeptide Knockout (VIP−/−) Mice with Cyclophosphamide (CYP)-Induced Cystitis

“…With respect to urinary bladder function, VIP −/− mice exhibit more pronounced urinary bladder hyperreflexia in response to CYP-induced cystitis compared to WT mice (Vizzard et al 2007). We have previously suggested that these differences may be due, in part, to differences in expression in urinary bladder inflammatory mediators under non-inflamed and inflamed conditions (Jensen et al 2008). The present studies demonstrate more robust upregulation of numerous inflammatory mediator genes in VIP −/− mice treated with CYP compared to WT mice treated with CYP.…”

“…Previous studies have demonstrated that p-CREB expression in lumbosacral dorsal root ganglia was greater in VIP −/− mice under basal conditions and after bladder inflammation induced by cyclophosphamide (Jensen et al 2008). Urinary bladder from VIP −/− mice exhibit greater mass, increased thickness of detrusor smooth muscle, and increased neurotrophic factor (e.g., nerve growth factor) content compared to WT mice (Jensen et al 2008).…”

“…Mice were housed (12-h light/dark cycle) in groups (five) in the University of Vermont animal vivarium with water and food provided ad libitum. VIP −/− and WT controls from the same litter were analyzed in most cases (Jensen et al 2008). When a WT littermate was unavailable, an age-matched control mouse from another C57BL/6 litter was used.…”

“…It has been shown that VIP inhibits the production of pro-inflammatory compounds (Chorny et al 2006), whereas VIP upregulates production of anti-inflammatory cytokines (Delgado et al 1999). We have suggested that differences in bladder hyperreflexia, p-CREB expression, and NGF expression in urinary bladder after bladder inflammation in VIP −/− mice may be attributed to a positive shift in the balance of proinflammatory mediators in the absence of VIP (Jensen et al 2008).…”

“…VIP may exert excitatory or inhibitory actions in neural pathways controlling micturition, and these functions may be altered with neural injury, disease, or inflammation. Previous studies have demonstrated increased expression of phosphorylated cAMP response element-binding protein (p-CREB) in bladder afferent cells in the lumbosacral dorsal root ganglia, increased nerve growth factor (NGF) content in the urinary bladder, and increased bladder hyperreflexia after CYP-induced cystitis compared to littermate, wild type (WT) mice (Vizzard et al 2007;Jensen et al 2008). In addition to roles as neurotransmitter or neuromodulator in autonomic nervous system pathways, VIP exhibits considerable antiinflammatory properties (Said 1991;Voice et al 2002;Szema et al 2006;Delgado et al 2000).…”