- Email: [email protected]
Effect of opioids on CXCL-8 production in healthy cats
Research in Veterinary Science 93 (2012) 1255–1257
Contents lists available at SciVerse ScienceDirect
Research in Veterinary Science journal homepage: www.elsevier.com/locate/rvsc
Effect of opioids on CXCL-8 production in healthy cats M.W. Harmon, S.M. Axiak, D.H. Yu, C.H. Chang, B. Fowler, A.E. DeClue ⇑ Comparative Internal Medicine Laboratory, College of Veterinary Medicine, University of Missouri, 900 East Campus Drive, Columbia, MO 65211, USA
a r t i c l e
i n f o
Article history: Received 18 October 2011 Accepted 4 February 2012
Keywords: Cat Cytokines Morphine Infection
a b s t r a c t The aim of this study was to evaluate the effect of opioid exposure on CXC chemokine ligand (CXCL)-8 production in cats using whole blood culture. Morphine, buprenorphine, fentanyl, and saline control were administered intravenously to five cats and whole blood pathogen associated molecular pattern motifinduced CXCL-8 production capacity was evaluated. Morphine potentiated CXCL-8 production. To further characterize this effect of morphine, morphine was incubated with whole blood ex vivo and pathogen associated molecular pattern motif-induced CXCL-8 production capacity was measured. There was a time and concentration dependent effect on CXCL-8 production, suggesting the proinflammatory effect of morphine is at least partially mediated by direct stimulatory effects on leukocytes. Additional investigation is indicated to assess the implications of the immunomodulatory actions of opioids in cats. Ó 2012 Elsevier Ltd. All rights reserved.
Opioids exert immunomodulatory effects resulting in increased infection rates, endocrine and metabolic alterations, and higher tumor reoccurrence rates. These are, in part, due to their profound effects on inflammatory mediator production including CXC chemokine ligand (CXCL)-8, a chemokine primarily involved in neutrophil activation and chemotaxis in several species (Mahajan et al., 2002; Odunayo et al., 2010). While opioids are clinically important drugs for pain management and are often used in diseases states characterized by neutrophilic inflammation in cats, to our knowledge, evaluation of the effects of opioids on CXCL-8 production in cats has not been performed. The purpose of this study was to evaluate the effect of morphine, fentanyl, and buprenorphine on pathogen associated molecular pattern (PAMP) motif stimulated CXCL-8 production utilizing a feline whole blood culture system. Ten adult, purpose bred domestic short-haired cats (Liberty Research) aged 2–4 years, weighting 4.5–7 kg were cared for according to the principles outlined in the NIH Guide for the Care and Use of Laboratory Animals and supervised by the University of Missouri Animal Care and Use Committee (#6119). Five cats had been instrumented with subcutaneous implantable vascular access ports (VAPs; Norfolk Vet Products) two years prior to this study. In the first set of experiments, five cats with VAPs were randomly assigned in a cross over, partial block design to receive standard clinical doses of morphine (0.5 mg/kg bolus followed by 0.1 mg/kg/h IV; Baxter Healthcare), fentanyl (4 lg/kg bolus followed by 4 lg/kg/h IV; Hospira Inc.), buprenorphine (0.01 mg/kg bolus followed by 1.7 lg/kg/h IV; Hospira Inc.) or control (equal volume/kg/h 0.9% NaCl) diluted to equal volume as a continuous ⇑ Corresponding author. Tel.: +1 573 882 7821; fax: +1 572 884 5444. E-mail address: [email protected] (A.E. DeClue). 0034-5288/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.rvsc.2012.02.002
rate infusion for 8 h (Boothe, 2001). Cats were given a minimum seven day washout period between treatments to allow adequate time for drug clearance based on each drug half-life (Lee et al., 2000, Taylor et al., 2001). Blood (3 mL) was collected aseptically into sodium heparin tubes (Tyco Health Care) at baseline (0 h) and 8 h after drug administration and immediately processed. This process was continued until all cats had received all treatments. Whole blood was diluted 1:2 with complete RPMI culture media, placed in 24 well plates, and stimulated with lipopolysaccharide (LPS) from Escherichia coli O127:B8 (1000 ng/mL), lipoteichoic acid (LTA) from Streptococcus faecalis (1000 ng/mL), peptidoglycan (PG) from Staphylococcus aureus (1000 ng/mL) (Sigma–Aldrich) or control phosphate buffered saline (PBS) (Stich and DeClue, 2011). After a 24 h incubation at 37 °C in room air with 5% CO2, the plates were centrifuged (2500g, 7 min) and supernatant collected and frozen at 80 °C until analysis. Supernatant CXCL-8 was measured using a feline specific ELISA (R&D Systems) (DeClue et al., 2009, 2011a). The inter-, intra-assay coefficient of variation and lower limit of detection are less than 5% and 62.5 pg/mL, respectively. In the second set of experiments, the direct effects of morphine on leukocyte responsiveness were evaluated. Blood (16 mL) was collected aseptically into sodium heparin tubes from the five remaining cats that did not receive any treatments and incubated with morphine (0, 10, 100 or 1000 ng/mL) for either 1 or 8 h. Then, blood was diluted with RPMI media, stimulated with PAMPs or PBS for 24 h and the supernatant collected and analyzed as for experiment 1. Leukocyte viability was assessed using trypan blue exclusion post incubation as previously described (DeClue et al., 2011b). Statistical analysis was performed using commercially available software (SigmaStat, Systat Software Inc.). A repeated measures ANOVA and post hoc Fisher Least Significant Difference method
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M.W. Harmon et al. / Research in Veterinary Science 93 (2012) 1255–1257
Fig. 1. Buprenorphine, fentanyl, morphine or control (saline) were administered to five healthy cats for 8 h in a crossover design with at least a 7 day washout period between treatments. Blood was collected and stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA) and peptidoglycan (PG) for 24 h. Supernatant CXCL-8 was measured using an ELISA. The bars represent the mean ± SE change in CXCL-8 production capacity from baseline to post-opioid infusion for each opioid and control (saline). Bars with the same letter are significantly different from one another (aP = 0.018, bP = 0.058, cP = 0.021, dP = 0.038, eP = 0.011).
was used with a P-value < 0.1 was considered statistically significant. This P-value was selected because of the inherent biologic variation and small sample size used in this study. Morphine administration resulted in a significant increase in CXCL-8 production capacity from LPS-stimulated whole blood compared to cats administered fentanyl (P = 0.021), buprenorphine (P = 0.058), or control (P = 0.018) (Fig. 1). Whole blood from cats treated with morphine had increased production of CXCL-8 when stimulated with LTA when compared to fentanyl (P = 0.011) and control (P = 0.038). There was no difference in PG-stimulated CXCL-8 among treatments. In vitro, morphine did not stimulate CXCL-8 production in the absence of PAMPs (data not shown). Incubating feline blood with 10 ng/mL and 100 ng/mL of morphine for 1 h in vitro resulted in down regulation of LTA (10 ng/mL, P = 0.002; 100 ng/mL, P = 0.009) and PG-induced (10 ng/mL, P = 0.009; 100 ng/mL, P = 0.016) CXCL-8 production (Fig. 2). However, this effect was not noted after 8 h incubation with morphine. The highest concentration of morphine, 1000 ng/mL, upregulated PAMP-stimulated
CXCL-8 production from whole blood in vitro after 1 h of exposure (LPS, P = 0.014; LTA, P = 0.029) and 8 h of exposure (LTA, P = 0.032; PG, P = 0.002). None of the alterations in CXCL-8 production could be attributed to differences in leukocyte viability (data not shown). In this study, in vivo exposure to morphine potentiated CXCL-8 production from feline whole blood leukocytes. Ex vivo, morphine had a differential effect on CXCL-8 production that was concentration and time dependent. Low concentrations of morphine resulted in blunting of CXCL-8 production at 1 h but this effect was not sustained at 8 h. Conversely, high concentration morphine enhanced PAMP stimulated CXCL-8 production regardless of incubation time. The concentration and time dependent immunomodulatory effects of morphine have been described in other species previously (Roy et al., 1998; Pacifici et al., 2000). Considering that peak plasma concentrations could exceed 100 ng/mL in the cat when morphine is used for pain management, and morphine is often administered over the course of several hours to days, the potential for CXCL-8 upregulation could have important implications for cats with pathology characterized by neutrophilic inflammation (Taylor et al., 2001). Morphine was selected for ex vivo evaluation because it was the only opioid tested that significantly altered CXCL-8 production in vivo. Therefore, we tested morphine to determine if it had a direct effect on leukocyte CXCL-8 production or if the effects were indirect (i.e. systemic). Our ex vivo results suggest that the pro-inflammatory effect of morphine is at least partially mediated by direct stimulatory effects on leukocytes. In other species, morphine promotes inflammation through direct MD-2/TLR4 and TLR2 signaling and activation of MyD88 dependent and independent signaling cascades (Li et al., 2009; Hutchinson et al., 2010). Morphine’s synergistic effect with PAMPs could be due to upregulation of these signaling cascades. Additionally, stimulation of the mu opioid receptor might directly regulate alpha chemokine gene expression and TLR2 signaling as it does in people (Mahajan et al., 2002; Bonnet et al., 2008). Ultimately, activation of leukocytes and inflammatory signaling pathways may promote proinflammatory cytokine and chemokine production leading to more severe inflammation in cats with naturally developing disease. Given these results, prospective studies evaluating the effects of opioid immunomodulation on morbidity and mortality in cats with inflammatory disease are warranted.
Fig. 2. Whole blood from six healthy cats was incubated with morphine 10, 100 or 1000 ng/mL or saline (0 ng/mL) for 1 or 8 h and then stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA) and peptidoglycan (PG) for 24 h. Supernatant CXCL-8 was measured using an ELISA. The bars represent the mean ± SE CXCL-8 production and the asterisk (⁄) indicates a significant (P < 0.04) difference from morphine 0 ng/mL.
M.W. Harmon et al. / Research in Veterinary Science 93 (2012) 1255–1257
Conflict of interest The authors have no conflict of interest to disclose. Acknowledgements The authors would like to acknowledge Dr. Juliana Amorim for her technical assistance with this study. Additionally, the authors would like to thank Norfolk Vet Products for their generous donation of the vascular access ports and Huber needles used in this study. References Bonnet, M.P., Beloeil, H., Benhamou, D., Mazoit, J.X., Asehnoune, K., 2008. The mu opioid receptor mediates morphine-induced tumor necrosis factor and interleukin-6 inhibition in toll-like receptor 2-stimulated monocytes. Anesthesia and Analgesia 106, 1142–1149. Boothe, D.M., 2001. Control of Pain In Small Animals: Opioid Agonists and Antagonists and Other Locally and Centrally Acting Analgesics. In: Boothe, D.M. (Ed.), Small Animal Clinical Pharmacology and Therapeutics. W.B. Saunders, Philidelphia, pp. 405–424. DeClue, A.E., Williams, K.J., Sharp, C., Haak, C., Lechner, E., Reinero, C.R., 2009. Systemic response to low-dose endotoxin infusion in cats. Veterinary Immunology and Immunopathology 132, 167–174. DeClue, A.E., Delgado, C., Chang, C.H., Sharp, C.R., 2011a. Clinical and immunologic assessment of sepsis and the systemic inflammatory response syndrome in cats. Journal of the American Veterinary Medical Association 238, 890–897. DeClue, A.E., Johnson, P.J., Day, J.R., Amorim, A.R., Honaker, A.R., 2011b. Pathogen associated molecular pattern motifs from Gram-positive and Gram-negative
1257
bacteria induce different inflammatory mediator profiles in equine blood. Veterinary Journal, E-pub ahead of print. Hutchinson, M.R., Zhang, Y., Shridhar, M., Evans, J.H., Buchanan, M.M., Zhao, T.X., Slivka, P.F., Coats, B.D., Rezvani, N., Wieseler, J., Hughes, T.S., Landgraf, K.E., Chan, S., Fong, S., Phipps, S., Falke, J.J., Leinwand, L.A., Maier, S.F., Yin, H., Rice, K.C., Watkins, L.R., 2010. Evidence that opioids may have toll-like receptor 4 and MD-2 effects. Brain, Behavior, and Immunity 24, 83–95. Lee, D.D., Papich, M.G., Hardie, E.M., 2000. Comparison of pharmacokinetics of fentanyl after intravenous and transdermal administration in cats. American Journal of Veterinary Research 61, 672–677. Li, Y., Sun, X., Zhang, Y., Huang, J., Hanley, G., Ferslew, K.E., Peng, Y., Yin, D., 2009. Morphine promotes apoptosis via TLR2, and this is negatively regulated by beta-arrestin 2. Biochemical and Biophysical Research Communications 378, 857–861. Mahajan, S.D., Schwartz, S.A., Shanahan, T.C., Chawda, R.P., Nair, M.P., 2002. Morphine regulates gene expression of alpha- and beta-chemokines and their receptors on astroglial cells via the opioid mu receptor. Journal of Immunology 169, 3589–3599. Odunayo, A., Dodam, J.R., Kerl, M.E., DeClue, A.E., 2010. Immunomodulatory effects of opioids. Journal of Veterinary Emergency and Critical Care 20, 376–385. Pacifici, R., di Carlo, S., Bacosi, A., Pichini, S., Zuccaro, P., 2000. Pharmacokinetics and cytokine production in heroin and morphine-treated mice. International Journal of Immunopharmacology 22, 603–614. Roy, S., Cain, K.J., Chapin, R.B., Charboneau, R.G., Barke, R.A., 1998. Morphine modulates NF kappa B activation in macrophages. Biochemical and Biophysical Research Communications 245, 392–396. Stich, A.N., DeClue, A.E., 2011. Pathogen associated molecular pattern-induced TNF, IL-1b, IL-6, and CXCL-8 production from feline whole blood culture. Research in Veterinary Science 90, 59–63. Taylor, P.M., Robertson, S.A., Dixon, M.J., Ruprah, M., Sear, J.W., Lascelles, B.D.X., Waters, C., Bloomfield, M., 2001. Morphine, pethidine, and buprenorphine disposition in the cat. Journal of Veterinary Pharmacology and Therapeutics 24, 391–398.
Contents lists available at SciVerse ScienceDirect
Research in Veterinary Science journal homepage: www.elsevier.com/locate/rvsc
Effect of opioids on CXCL-8 production in healthy cats M.W. Harmon, S.M. Axiak, D.H. Yu, C.H. Chang, B. Fowler, A.E. DeClue ⇑ Comparative Internal Medicine Laboratory, College of Veterinary Medicine, University of Missouri, 900 East Campus Drive, Columbia, MO 65211, USA
a r t i c l e
i n f o
Article history: Received 18 October 2011 Accepted 4 February 2012
Keywords: Cat Cytokines Morphine Infection
a b s t r a c t The aim of this study was to evaluate the effect of opioid exposure on CXC chemokine ligand (CXCL)-8 production in cats using whole blood culture. Morphine, buprenorphine, fentanyl, and saline control were administered intravenously to five cats and whole blood pathogen associated molecular pattern motifinduced CXCL-8 production capacity was evaluated. Morphine potentiated CXCL-8 production. To further characterize this effect of morphine, morphine was incubated with whole blood ex vivo and pathogen associated molecular pattern motif-induced CXCL-8 production capacity was measured. There was a time and concentration dependent effect on CXCL-8 production, suggesting the proinflammatory effect of morphine is at least partially mediated by direct stimulatory effects on leukocytes. Additional investigation is indicated to assess the implications of the immunomodulatory actions of opioids in cats. Ó 2012 Elsevier Ltd. All rights reserved.
Opioids exert immunomodulatory effects resulting in increased infection rates, endocrine and metabolic alterations, and higher tumor reoccurrence rates. These are, in part, due to their profound effects on inflammatory mediator production including CXC chemokine ligand (CXCL)-8, a chemokine primarily involved in neutrophil activation and chemotaxis in several species (Mahajan et al., 2002; Odunayo et al., 2010). While opioids are clinically important drugs for pain management and are often used in diseases states characterized by neutrophilic inflammation in cats, to our knowledge, evaluation of the effects of opioids on CXCL-8 production in cats has not been performed. The purpose of this study was to evaluate the effect of morphine, fentanyl, and buprenorphine on pathogen associated molecular pattern (PAMP) motif stimulated CXCL-8 production utilizing a feline whole blood culture system. Ten adult, purpose bred domestic short-haired cats (Liberty Research) aged 2–4 years, weighting 4.5–7 kg were cared for according to the principles outlined in the NIH Guide for the Care and Use of Laboratory Animals and supervised by the University of Missouri Animal Care and Use Committee (#6119). Five cats had been instrumented with subcutaneous implantable vascular access ports (VAPs; Norfolk Vet Products) two years prior to this study. In the first set of experiments, five cats with VAPs were randomly assigned in a cross over, partial block design to receive standard clinical doses of morphine (0.5 mg/kg bolus followed by 0.1 mg/kg/h IV; Baxter Healthcare), fentanyl (4 lg/kg bolus followed by 4 lg/kg/h IV; Hospira Inc.), buprenorphine (0.01 mg/kg bolus followed by 1.7 lg/kg/h IV; Hospira Inc.) or control (equal volume/kg/h 0.9% NaCl) diluted to equal volume as a continuous ⇑ Corresponding author. Tel.: +1 573 882 7821; fax: +1 572 884 5444. E-mail address: [email protected] (A.E. DeClue). 0034-5288/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.rvsc.2012.02.002
rate infusion for 8 h (Boothe, 2001). Cats were given a minimum seven day washout period between treatments to allow adequate time for drug clearance based on each drug half-life (Lee et al., 2000, Taylor et al., 2001). Blood (3 mL) was collected aseptically into sodium heparin tubes (Tyco Health Care) at baseline (0 h) and 8 h after drug administration and immediately processed. This process was continued until all cats had received all treatments. Whole blood was diluted 1:2 with complete RPMI culture media, placed in 24 well plates, and stimulated with lipopolysaccharide (LPS) from Escherichia coli O127:B8 (1000 ng/mL), lipoteichoic acid (LTA) from Streptococcus faecalis (1000 ng/mL), peptidoglycan (PG) from Staphylococcus aureus (1000 ng/mL) (Sigma–Aldrich) or control phosphate buffered saline (PBS) (Stich and DeClue, 2011). After a 24 h incubation at 37 °C in room air with 5% CO2, the plates were centrifuged (2500g, 7 min) and supernatant collected and frozen at 80 °C until analysis. Supernatant CXCL-8 was measured using a feline specific ELISA (R&D Systems) (DeClue et al., 2009, 2011a). The inter-, intra-assay coefficient of variation and lower limit of detection are less than 5% and 62.5 pg/mL, respectively. In the second set of experiments, the direct effects of morphine on leukocyte responsiveness were evaluated. Blood (16 mL) was collected aseptically into sodium heparin tubes from the five remaining cats that did not receive any treatments and incubated with morphine (0, 10, 100 or 1000 ng/mL) for either 1 or 8 h. Then, blood was diluted with RPMI media, stimulated with PAMPs or PBS for 24 h and the supernatant collected and analyzed as for experiment 1. Leukocyte viability was assessed using trypan blue exclusion post incubation as previously described (DeClue et al., 2011b). Statistical analysis was performed using commercially available software (SigmaStat, Systat Software Inc.). A repeated measures ANOVA and post hoc Fisher Least Significant Difference method
1256
M.W. Harmon et al. / Research in Veterinary Science 93 (2012) 1255–1257
Fig. 1. Buprenorphine, fentanyl, morphine or control (saline) were administered to five healthy cats for 8 h in a crossover design with at least a 7 day washout period between treatments. Blood was collected and stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA) and peptidoglycan (PG) for 24 h. Supernatant CXCL-8 was measured using an ELISA. The bars represent the mean ± SE change in CXCL-8 production capacity from baseline to post-opioid infusion for each opioid and control (saline). Bars with the same letter are significantly different from one another (aP = 0.018, bP = 0.058, cP = 0.021, dP = 0.038, eP = 0.011).
was used with a P-value < 0.1 was considered statistically significant. This P-value was selected because of the inherent biologic variation and small sample size used in this study. Morphine administration resulted in a significant increase in CXCL-8 production capacity from LPS-stimulated whole blood compared to cats administered fentanyl (P = 0.021), buprenorphine (P = 0.058), or control (P = 0.018) (Fig. 1). Whole blood from cats treated with morphine had increased production of CXCL-8 when stimulated with LTA when compared to fentanyl (P = 0.011) and control (P = 0.038). There was no difference in PG-stimulated CXCL-8 among treatments. In vitro, morphine did not stimulate CXCL-8 production in the absence of PAMPs (data not shown). Incubating feline blood with 10 ng/mL and 100 ng/mL of morphine for 1 h in vitro resulted in down regulation of LTA (10 ng/mL, P = 0.002; 100 ng/mL, P = 0.009) and PG-induced (10 ng/mL, P = 0.009; 100 ng/mL, P = 0.016) CXCL-8 production (Fig. 2). However, this effect was not noted after 8 h incubation with morphine. The highest concentration of morphine, 1000 ng/mL, upregulated PAMP-stimulated
CXCL-8 production from whole blood in vitro after 1 h of exposure (LPS, P = 0.014; LTA, P = 0.029) and 8 h of exposure (LTA, P = 0.032; PG, P = 0.002). None of the alterations in CXCL-8 production could be attributed to differences in leukocyte viability (data not shown). In this study, in vivo exposure to morphine potentiated CXCL-8 production from feline whole blood leukocytes. Ex vivo, morphine had a differential effect on CXCL-8 production that was concentration and time dependent. Low concentrations of morphine resulted in blunting of CXCL-8 production at 1 h but this effect was not sustained at 8 h. Conversely, high concentration morphine enhanced PAMP stimulated CXCL-8 production regardless of incubation time. The concentration and time dependent immunomodulatory effects of morphine have been described in other species previously (Roy et al., 1998; Pacifici et al., 2000). Considering that peak plasma concentrations could exceed 100 ng/mL in the cat when morphine is used for pain management, and morphine is often administered over the course of several hours to days, the potential for CXCL-8 upregulation could have important implications for cats with pathology characterized by neutrophilic inflammation (Taylor et al., 2001). Morphine was selected for ex vivo evaluation because it was the only opioid tested that significantly altered CXCL-8 production in vivo. Therefore, we tested morphine to determine if it had a direct effect on leukocyte CXCL-8 production or if the effects were indirect (i.e. systemic). Our ex vivo results suggest that the pro-inflammatory effect of morphine is at least partially mediated by direct stimulatory effects on leukocytes. In other species, morphine promotes inflammation through direct MD-2/TLR4 and TLR2 signaling and activation of MyD88 dependent and independent signaling cascades (Li et al., 2009; Hutchinson et al., 2010). Morphine’s synergistic effect with PAMPs could be due to upregulation of these signaling cascades. Additionally, stimulation of the mu opioid receptor might directly regulate alpha chemokine gene expression and TLR2 signaling as it does in people (Mahajan et al., 2002; Bonnet et al., 2008). Ultimately, activation of leukocytes and inflammatory signaling pathways may promote proinflammatory cytokine and chemokine production leading to more severe inflammation in cats with naturally developing disease. Given these results, prospective studies evaluating the effects of opioid immunomodulation on morbidity and mortality in cats with inflammatory disease are warranted.
Fig. 2. Whole blood from six healthy cats was incubated with morphine 10, 100 or 1000 ng/mL or saline (0 ng/mL) for 1 or 8 h and then stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA) and peptidoglycan (PG) for 24 h. Supernatant CXCL-8 was measured using an ELISA. The bars represent the mean ± SE CXCL-8 production and the asterisk (⁄) indicates a significant (P < 0.04) difference from morphine 0 ng/mL.
M.W. Harmon et al. / Research in Veterinary Science 93 (2012) 1255–1257
Conflict of interest The authors have no conflict of interest to disclose. Acknowledgements The authors would like to acknowledge Dr. Juliana Amorim for her technical assistance with this study. Additionally, the authors would like to thank Norfolk Vet Products for their generous donation of the vascular access ports and Huber needles used in this study. References Bonnet, M.P., Beloeil, H., Benhamou, D., Mazoit, J.X., Asehnoune, K., 2008. The mu opioid receptor mediates morphine-induced tumor necrosis factor and interleukin-6 inhibition in toll-like receptor 2-stimulated monocytes. Anesthesia and Analgesia 106, 1142–1149. Boothe, D.M., 2001. Control of Pain In Small Animals: Opioid Agonists and Antagonists and Other Locally and Centrally Acting Analgesics. In: Boothe, D.M. (Ed.), Small Animal Clinical Pharmacology and Therapeutics. W.B. Saunders, Philidelphia, pp. 405–424. DeClue, A.E., Williams, K.J., Sharp, C., Haak, C., Lechner, E., Reinero, C.R., 2009. Systemic response to low-dose endotoxin infusion in cats. Veterinary Immunology and Immunopathology 132, 167–174. DeClue, A.E., Delgado, C., Chang, C.H., Sharp, C.R., 2011a. Clinical and immunologic assessment of sepsis and the systemic inflammatory response syndrome in cats. Journal of the American Veterinary Medical Association 238, 890–897. DeClue, A.E., Johnson, P.J., Day, J.R., Amorim, A.R., Honaker, A.R., 2011b. Pathogen associated molecular pattern motifs from Gram-positive and Gram-negative
1257
bacteria induce different inflammatory mediator profiles in equine blood. Veterinary Journal, E-pub ahead of print. Hutchinson, M.R., Zhang, Y., Shridhar, M., Evans, J.H., Buchanan, M.M., Zhao, T.X., Slivka, P.F., Coats, B.D., Rezvani, N., Wieseler, J., Hughes, T.S., Landgraf, K.E., Chan, S., Fong, S., Phipps, S., Falke, J.J., Leinwand, L.A., Maier, S.F., Yin, H., Rice, K.C., Watkins, L.R., 2010. Evidence that opioids may have toll-like receptor 4 and MD-2 effects. Brain, Behavior, and Immunity 24, 83–95. Lee, D.D., Papich, M.G., Hardie, E.M., 2000. Comparison of pharmacokinetics of fentanyl after intravenous and transdermal administration in cats. American Journal of Veterinary Research 61, 672–677. Li, Y., Sun, X., Zhang, Y., Huang, J., Hanley, G., Ferslew, K.E., Peng, Y., Yin, D., 2009. Morphine promotes apoptosis via TLR2, and this is negatively regulated by beta-arrestin 2. Biochemical and Biophysical Research Communications 378, 857–861. Mahajan, S.D., Schwartz, S.A., Shanahan, T.C., Chawda, R.P., Nair, M.P., 2002. Morphine regulates gene expression of alpha- and beta-chemokines and their receptors on astroglial cells via the opioid mu receptor. Journal of Immunology 169, 3589–3599. Odunayo, A., Dodam, J.R., Kerl, M.E., DeClue, A.E., 2010. Immunomodulatory effects of opioids. Journal of Veterinary Emergency and Critical Care 20, 376–385. Pacifici, R., di Carlo, S., Bacosi, A., Pichini, S., Zuccaro, P., 2000. Pharmacokinetics and cytokine production in heroin and morphine-treated mice. International Journal of Immunopharmacology 22, 603–614. Roy, S., Cain, K.J., Chapin, R.B., Charboneau, R.G., Barke, R.A., 1998. Morphine modulates NF kappa B activation in macrophages. Biochemical and Biophysical Research Communications 245, 392–396. Stich, A.N., DeClue, A.E., 2011. Pathogen associated molecular pattern-induced TNF, IL-1b, IL-6, and CXCL-8 production from feline whole blood culture. Research in Veterinary Science 90, 59–63. Taylor, P.M., Robertson, S.A., Dixon, M.J., Ruprah, M., Sear, J.W., Lascelles, B.D.X., Waters, C., Bloomfield, M., 2001. Morphine, pethidine, and buprenorphine disposition in the cat. Journal of Veterinary Pharmacology and Therapeutics 24, 391–398.