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Cellular localization of kinin B1 receptor in the spinal cord of streptozotocin-diabetic rats with a fluorescent [Nalpha-Bodipy]-des-Arg9-bradykinin.

Talbot S, Théberge-Turmel P, Liazoghli D, Sénécal J, Gaudreau P, Couture R - J Neuroinflammation (2009)

Bottom Line: Four days post-STZ treatment, B1R expression was confirmed by quantitative real-time PCR and autoradiography.BdABK failed to displace the B2R radioligand but displaced the B1R radioligand (IC50 = 5.3 nM).In comparison, IC50 values of B1R selective antagonist R-715 and B1R agonist des-Arg9-BK were 4.3 nM and 19 nM, respectively.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, Faculty of Medicine, Université de Montréal, Succursale Downtown, Montréal, Québec, Canada. sebastien.talbot@umontreal.ca

ABSTRACT

Background: The kinin B1 receptor (B1R) is upregulated by pro-inflammatory cytokines, bacterial endotoxins and hyperglycaemia-induced oxidative stress. In animal models of diabetes, it contributes to pain polyneuropathy. This study aims at defining the cellular localization of B1R in thoracic spinal cord of type 1 diabetic rats by confocal microscopy with the use of a fluorescent agonist, [Nalpha-Bodipy]-des-Arg9-BK (BdABK) and selective antibodies.

Methods: Diabetes was induced by streptozotocin (STZ; 65 mg/kg, i.p.). Four days post-STZ treatment, B1R expression was confirmed by quantitative real-time PCR and autoradiography. The B1R selectivity of BdABK was determined by assessing its ability to displace B1R [125I]-HPP-desArg10-Hoe140 and B2R [125I]-HPP-Hoe 140 radioligands. The in vivo activity of BdABK was also evaluated on thermal hyperalgesia.

Results: B1R was increased by 18-fold (mRNA) and 2.7-fold (binding sites) in the thoracic spinal cord of STZ-treated rats when compared to control. BdABK failed to displace the B2R radioligand but displaced the B1R radioligand (IC50 = 5.3 nM). In comparison, IC50 values of B1R selective antagonist R-715 and B1R agonist des-Arg9-BK were 4.3 nM and 19 nM, respectively. Intraperitoneal BdABK and des-Arg9-BK elicited dose-dependent thermal hyperalgesia in STZ-treated rats but not in control rats. The B1R fluorescent agonist was co-localized with immunomarkers of microglia, astrocytes and sensory C fibers in the spinal cord of STZ-treated rats.

Conclusion: The induction and up-regulation of B1R in glial and sensory cells of the spinal cord in STZ-diabetic rats reinforce the idea that kinin B1R is an important target for drug development in pain processes.

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The ability of intraperitoneally injected [Nα-Bodipy]-des-Arg9-BK and its native agonist, des-Arg9-BK, to alter the paw withdrawal threshold in STZ-treated and control rats. Data represent maximal effects and are the average of 3 readings taken at 9, 12 and 15 min post-injection in 3 rats per group. Statistical comparison to control (*) and 2250 μg/kg des-Arg9-BK (+) are indicated by * + P < 0.05; ** P < 0.01; *** P < 0.001.
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Figure 5: The ability of intraperitoneally injected [Nα-Bodipy]-des-Arg9-BK and its native agonist, des-Arg9-BK, to alter the paw withdrawal threshold in STZ-treated and control rats. Data represent maximal effects and are the average of 3 readings taken at 9, 12 and 15 min post-injection in 3 rats per group. Statistical comparison to control (*) and 2250 μg/kg des-Arg9-BK (+) are indicated by * + P < 0.05; ** P < 0.01; *** P < 0.001.

Mentions: The in vivo effect of BdABK on pain behavior was assessed by determining its ability to induce thermal hyperalgesia upon intraperitoneal injection in STZ-treated rats. As expected, BdABK and des-Arg9-BK had no significant effect on the nociceptive threshold in control rats, yet both agonists caused thermal hyperalgesia in STZ-diabetic rats at 0.225 and 2.25 mg/kg. These effects were dose-dependent and significant when compared to saline or control (Fig. 5). BdABK was however slightly but significantly less potent than des-Arg9-BK to induce hyperalgesia at the highest dose. As exemplified by des-Arg9-BK, this response peaked at 15 min post-injection and was reversible after 30 min (Fig. 6).


Cellular localization of kinin B1 receptor in the spinal cord of streptozotocin-diabetic rats with a fluorescent [Nalpha-Bodipy]-des-Arg9-bradykinin.

Talbot S, Théberge-Turmel P, Liazoghli D, Sénécal J, Gaudreau P, Couture R - J Neuroinflammation (2009)

The ability of intraperitoneally injected [Nα-Bodipy]-des-Arg9-BK and its native agonist, des-Arg9-BK, to alter the paw withdrawal threshold in STZ-treated and control rats. Data represent maximal effects and are the average of 3 readings taken at 9, 12 and 15 min post-injection in 3 rats per group. Statistical comparison to control (*) and 2250 μg/kg des-Arg9-BK (+) are indicated by * + P < 0.05; ** P < 0.01; *** P < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2667487&req=5

Figure 5: The ability of intraperitoneally injected [Nα-Bodipy]-des-Arg9-BK and its native agonist, des-Arg9-BK, to alter the paw withdrawal threshold in STZ-treated and control rats. Data represent maximal effects and are the average of 3 readings taken at 9, 12 and 15 min post-injection in 3 rats per group. Statistical comparison to control (*) and 2250 μg/kg des-Arg9-BK (+) are indicated by * + P < 0.05; ** P < 0.01; *** P < 0.001.
Mentions: The in vivo effect of BdABK on pain behavior was assessed by determining its ability to induce thermal hyperalgesia upon intraperitoneal injection in STZ-treated rats. As expected, BdABK and des-Arg9-BK had no significant effect on the nociceptive threshold in control rats, yet both agonists caused thermal hyperalgesia in STZ-diabetic rats at 0.225 and 2.25 mg/kg. These effects were dose-dependent and significant when compared to saline or control (Fig. 5). BdABK was however slightly but significantly less potent than des-Arg9-BK to induce hyperalgesia at the highest dose. As exemplified by des-Arg9-BK, this response peaked at 15 min post-injection and was reversible after 30 min (Fig. 6).

Bottom Line: Four days post-STZ treatment, B1R expression was confirmed by quantitative real-time PCR and autoradiography.BdABK failed to displace the B2R radioligand but displaced the B1R radioligand (IC50 = 5.3 nM).In comparison, IC50 values of B1R selective antagonist R-715 and B1R agonist des-Arg9-BK were 4.3 nM and 19 nM, respectively.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, Faculty of Medicine, Université de Montréal, Succursale Downtown, Montréal, Québec, Canada. sebastien.talbot@umontreal.ca

ABSTRACT

Background: The kinin B1 receptor (B1R) is upregulated by pro-inflammatory cytokines, bacterial endotoxins and hyperglycaemia-induced oxidative stress. In animal models of diabetes, it contributes to pain polyneuropathy. This study aims at defining the cellular localization of B1R in thoracic spinal cord of type 1 diabetic rats by confocal microscopy with the use of a fluorescent agonist, [Nalpha-Bodipy]-des-Arg9-BK (BdABK) and selective antibodies.

Methods: Diabetes was induced by streptozotocin (STZ; 65 mg/kg, i.p.). Four days post-STZ treatment, B1R expression was confirmed by quantitative real-time PCR and autoradiography. The B1R selectivity of BdABK was determined by assessing its ability to displace B1R [125I]-HPP-desArg10-Hoe140 and B2R [125I]-HPP-Hoe 140 radioligands. The in vivo activity of BdABK was also evaluated on thermal hyperalgesia.

Results: B1R was increased by 18-fold (mRNA) and 2.7-fold (binding sites) in the thoracic spinal cord of STZ-treated rats when compared to control. BdABK failed to displace the B2R radioligand but displaced the B1R radioligand (IC50 = 5.3 nM). In comparison, IC50 values of B1R selective antagonist R-715 and B1R agonist des-Arg9-BK were 4.3 nM and 19 nM, respectively. Intraperitoneal BdABK and des-Arg9-BK elicited dose-dependent thermal hyperalgesia in STZ-treated rats but not in control rats. The B1R fluorescent agonist was co-localized with immunomarkers of microglia, astrocytes and sensory C fibers in the spinal cord of STZ-treated rats.

Conclusion: The induction and up-regulation of B1R in glial and sensory cells of the spinal cord in STZ-diabetic rats reinforce the idea that kinin B1R is an important target for drug development in pain processes.

Show MeSH
Related in: MedlinePlus