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Influence of clonidine and ketamine on m-RNA expression in a model of opioid-induced hyperalgesia in mice.

Ohnesorge H, Feng Z, Zitta K, Steinfath M, Albrecht M, Bein B - PLoS ONE (2013)

Bottom Line: Sub-acute morphine administration resulted in a decrease of NMDAR1 and Arrb2 whereas during longer opioid treatment the expression NMDAR1 and Arrb2 mRNA increased again to baseline values.Coadministration of s-ketamine or clonidine resulted in a reversal of the mechanical hyperalgesia and inhibited the normalization of NMDAR1 mRNA expression but had no effect on the expression of Arrb2 mRNA.The results indicate that co-administration of clonidine or ketamine may influence the underlying mechanisms of OIH.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.

ABSTRACT

Background: We investigated the influence of morphine and ketamine or clonidine in mice on the expression of genes that may mediate pronociceptive opioid effects.

Material and methods: C57BL/6 mice received morphine injections thrice daily using increasing doses (5-20 mg∙kg(-1)) for 3 days (sub-acute, n=6) or 14 days (chronic, n=6) and additionally either s-ketamine (5 mg∙kg(-1), n=6) or clonidine (0.1 mg∙kg(-1), n=6). Tail flick test and the assessment of the mechanical withdrawal threshold of the hindpaw was performed during and 4 days after cessation of opioid treatment. Upon completion of the behavioural testing the mRNA-concentration of the NMDA receptor (NMDAR1) and β-arrestin 2 (Arrb2) were measured by PCR.

Results: Chronic opioid treatment resulted in a delay of the tail flick latency with a rapid on- and offset. Simultaneously the mice developed a static mechanical hyperalgesia with a delayed onset that that outlasted the morphine treatment. Sub-acute morphine administration resulted in a decrease of NMDAR1 and Arrb2 whereas during longer opioid treatment the expression NMDAR1 and Arrb2 mRNA increased again to baseline values. Coadministration of s-ketamine or clonidine resulted in a reversal of the mechanical hyperalgesia and inhibited the normalization of NMDAR1 mRNA expression but had no effect on the expression of Arrb2 mRNA.

Conclusion: In the model of chronic morphine therapy the antinociceptive effects of morphine are represented by the thermal analgesia while the proniceptive effects are represented by the mechanical hyperalgesia. The results indicate that the regulation of the expression of NMDAR1 and Arrb2 may be associated to the development of OIH in mice.

Perspective: The results indicate that co-administration of clonidine or ketamine may influence the underlying mechanisms of OIH.

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Related in: MedlinePlus

Regulation of NMDAR1 mRNA in mice brain.Each PCR experiment was repeated 3 times per animal (n=6), one representative PCR result is shown (A). Values below the bands display the average level of band densities of NMDAR1 compared with those of the housekeeping gene Hprt1 (not shown) for each group (mean ± SEM). Regulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P (B). Columns show the mean upregulation or downregulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P, bars denote SEM; numbers display the numbers of mice in each group. AM: acute morphine administration group; CM: chronic morphine administration group; LM: coadministration of morphine with clonidine group; KM: coadministration of morphine with s-ketamine group. #P<0.05; ##P<0.01; ###P<0.001 compared with group P, *P<0.001 compared with group AM, and +P<0.001 compared with group CM.
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pone-0079567-g005: Regulation of NMDAR1 mRNA in mice brain.Each PCR experiment was repeated 3 times per animal (n=6), one representative PCR result is shown (A). Values below the bands display the average level of band densities of NMDAR1 compared with those of the housekeeping gene Hprt1 (not shown) for each group (mean ± SEM). Regulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P (B). Columns show the mean upregulation or downregulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P, bars denote SEM; numbers display the numbers of mice in each group. AM: acute morphine administration group; CM: chronic morphine administration group; LM: coadministration of morphine with clonidine group; KM: coadministration of morphine with s-ketamine group. #P<0.05; ##P<0.01; ###P<0.001 compared with group P, *P<0.001 compared with group AM, and +P<0.001 compared with group CM.

Mentions: Compared with the placebo group, we observed a statistically significant downregulation both in NMDAR1 mRNA expression and in Arrb2 mRNA expression in group AM (Figures 5 and 6, P<0.01). After chronic morphine administration (group CM) gene expressions of NMDAR1 mRNA and Arrb2 mRNA were normalized to baseline value (Arrb2, P<0.01 vs. AM; NMDAR1, P<0.001 vs. AM) back to baseline values (p>0.05 compared to group P). Coadministration of s-ketamine (group KM) and clonidine (group LM) inhibited the normalization of the expression of NMDAR1 mRNA (Figure 5), while both drugs had no effect on the expression of Arrb2 (Figure 6). Neither sub-acute nor chronic morphine administration influenced the expression of c-Fos, Jun-b and Arrb1 mRNA. The expression of c-Fos, Jun-b and Arrb1 mRNA was not influenced by the coadministration of clonidine or s-ketamine except of a significant upregulation of Arrb1 in group LM (p<0.05, data not shown).


Influence of clonidine and ketamine on m-RNA expression in a model of opioid-induced hyperalgesia in mice.

Ohnesorge H, Feng Z, Zitta K, Steinfath M, Albrecht M, Bein B - PLoS ONE (2013)

Regulation of NMDAR1 mRNA in mice brain.Each PCR experiment was repeated 3 times per animal (n=6), one representative PCR result is shown (A). Values below the bands display the average level of band densities of NMDAR1 compared with those of the housekeeping gene Hprt1 (not shown) for each group (mean ± SEM). Regulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P (B). Columns show the mean upregulation or downregulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P, bars denote SEM; numbers display the numbers of mice in each group. AM: acute morphine administration group; CM: chronic morphine administration group; LM: coadministration of morphine with clonidine group; KM: coadministration of morphine with s-ketamine group. #P<0.05; ##P<0.01; ###P<0.001 compared with group P, *P<0.001 compared with group AM, and +P<0.001 compared with group CM.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3815130&req=5

pone-0079567-g005: Regulation of NMDAR1 mRNA in mice brain.Each PCR experiment was repeated 3 times per animal (n=6), one representative PCR result is shown (A). Values below the bands display the average level of band densities of NMDAR1 compared with those of the housekeeping gene Hprt1 (not shown) for each group (mean ± SEM). Regulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P (B). Columns show the mean upregulation or downregulation of NMDAR1 mRNA expression in group AM, CM, LM and KM compared with group P, bars denote SEM; numbers display the numbers of mice in each group. AM: acute morphine administration group; CM: chronic morphine administration group; LM: coadministration of morphine with clonidine group; KM: coadministration of morphine with s-ketamine group. #P<0.05; ##P<0.01; ###P<0.001 compared with group P, *P<0.001 compared with group AM, and +P<0.001 compared with group CM.
Mentions: Compared with the placebo group, we observed a statistically significant downregulation both in NMDAR1 mRNA expression and in Arrb2 mRNA expression in group AM (Figures 5 and 6, P<0.01). After chronic morphine administration (group CM) gene expressions of NMDAR1 mRNA and Arrb2 mRNA were normalized to baseline value (Arrb2, P<0.01 vs. AM; NMDAR1, P<0.001 vs. AM) back to baseline values (p>0.05 compared to group P). Coadministration of s-ketamine (group KM) and clonidine (group LM) inhibited the normalization of the expression of NMDAR1 mRNA (Figure 5), while both drugs had no effect on the expression of Arrb2 (Figure 6). Neither sub-acute nor chronic morphine administration influenced the expression of c-Fos, Jun-b and Arrb1 mRNA. The expression of c-Fos, Jun-b and Arrb1 mRNA was not influenced by the coadministration of clonidine or s-ketamine except of a significant upregulation of Arrb1 in group LM (p<0.05, data not shown).

Bottom Line: Sub-acute morphine administration resulted in a decrease of NMDAR1 and Arrb2 whereas during longer opioid treatment the expression NMDAR1 and Arrb2 mRNA increased again to baseline values.Coadministration of s-ketamine or clonidine resulted in a reversal of the mechanical hyperalgesia and inhibited the normalization of NMDAR1 mRNA expression but had no effect on the expression of Arrb2 mRNA.The results indicate that co-administration of clonidine or ketamine may influence the underlying mechanisms of OIH.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.

ABSTRACT

Background: We investigated the influence of morphine and ketamine or clonidine in mice on the expression of genes that may mediate pronociceptive opioid effects.

Material and methods: C57BL/6 mice received morphine injections thrice daily using increasing doses (5-20 mg∙kg(-1)) for 3 days (sub-acute, n=6) or 14 days (chronic, n=6) and additionally either s-ketamine (5 mg∙kg(-1), n=6) or clonidine (0.1 mg∙kg(-1), n=6). Tail flick test and the assessment of the mechanical withdrawal threshold of the hindpaw was performed during and 4 days after cessation of opioid treatment. Upon completion of the behavioural testing the mRNA-concentration of the NMDA receptor (NMDAR1) and β-arrestin 2 (Arrb2) were measured by PCR.

Results: Chronic opioid treatment resulted in a delay of the tail flick latency with a rapid on- and offset. Simultaneously the mice developed a static mechanical hyperalgesia with a delayed onset that that outlasted the morphine treatment. Sub-acute morphine administration resulted in a decrease of NMDAR1 and Arrb2 whereas during longer opioid treatment the expression NMDAR1 and Arrb2 mRNA increased again to baseline values. Coadministration of s-ketamine or clonidine resulted in a reversal of the mechanical hyperalgesia and inhibited the normalization of NMDAR1 mRNA expression but had no effect on the expression of Arrb2 mRNA.

Conclusion: In the model of chronic morphine therapy the antinociceptive effects of morphine are represented by the thermal analgesia while the proniceptive effects are represented by the mechanical hyperalgesia. The results indicate that the regulation of the expression of NMDAR1 and Arrb2 may be associated to the development of OIH in mice.

Perspective: The results indicate that co-administration of clonidine or ketamine may influence the underlying mechanisms of OIH.

Show MeSH
Related in: MedlinePlus