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Permanent lesion in rostral ventromedial medulla potentiates swim stress-induced analgesia in formalin test.

Shamsizadeh A, Soliemani N, Mohammad-Zadeh M, Azhdari-Zarmehri H - Iran J Basic Med Sci (2014)

Bottom Line: For permanent lesion of RVM, R-SKF38393 was injected into the RVM.Forced swim stress in water was employed in adult male rats.Furthermore, R-SKF38393 had pronociceptive effects in phase2B whereas injections of R-SKF38393 resulted in significant difference in nociceptive bahaviours in all phases of formalin test (P<0.05).

View Article: PubMed Central - PubMed

Affiliation: Physiology-Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran.

ABSTRACT

Objective(s): There are many reports about the role of rostral ventromedial medulla (RVM) in modulating stress-induced analgesia (SIA). In the previous study we demonstrated that temporal inactivation of RVM by lidocaine potentiated stress-induced analgesia. In this study, we investigated the effect of permanent lesion of the RVM on SIA by using formalin test as a model of acute inflammatory pain.

Materials and methods: Three sets of experiments were conducted: (1) Application of stress protocol (2) Formalin injection after exposing the animals to the swim stress (3) Either the relevant vehicle or dopamine receptor 1 (D1) agonist R-SKF38393 was injected into the RVM to cause a lesion. For permanent lesion of RVM, R-SKF38393 was injected into the RVM. Forced swim stress in water was employed in adult male rats. Nociceptive responses were measured by formalin test (50µl injection of formalin 2% subcutaneously into hind paw) and pain related behaviors were monitored for 90 min.

Results: In the unstressed rats, permanent lesion of the RVM by R-SKF38393 decreased formalin-induced nociceptive behaviors in phase 1, while in stressed rats, injection of R-SKF38393 into the RVM potentiated swim stress-induced antinociception in phase 1 and interphase, phase 2A of formalin test. Furthermore, R-SKF38393 had pronociceptive effects in phase2B whereas injections of R-SKF38393 resulted in significant difference in nociceptive bahaviours in all phases of formalin test (P<0.05).

Conclusion: The result of the present study demonstrated that permanent inactivation of RVM can potentiate stress-induced analgesia in formalin test.

No MeSH data available.


Related in: MedlinePlus

Time scores of nociceptive behaviours induced by formalin (mean ±SEM of 9-10 rats per group) following swim stress measured every 3 min for 90 min (A) and bar chart for formalin test after swim stress in 50-cm high water and control group (B). The columns represent the mean of nociceptive score in each phase: phase 1 (min 1–7), interphase (min 8–14) and phase 2A (min 15–60) and phase 2B (min 61–90), (B). * P<0.05; ** P<0.01 and *** P<0.001 in comparison with control group
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Figure 3: Time scores of nociceptive behaviours induced by formalin (mean ±SEM of 9-10 rats per group) following swim stress measured every 3 min for 90 min (A) and bar chart for formalin test after swim stress in 50-cm high water and control group (B). The columns represent the mean of nociceptive score in each phase: phase 1 (min 1–7), interphase (min 8–14) and phase 2A (min 15–60) and phase 2B (min 61–90), (B). * P<0.05; ** P<0.01 and *** P<0.001 in comparison with control group

Mentions: Swim stress potentiated the antinociceptive response in phase 1 [T(1, 14)=2.90; P=0.011; (Figure 2B)], interphase [T (1, 14)=3.214; P=0.001; (Figure 2B)], and phase 2A [T (1, 14)=3.074; P=0.008; (Figure 2B)], and had pronociceptive effect on phase 2B [T (1, 14)=2.751; P=0.021; (Figure 2B)].


Permanent lesion in rostral ventromedial medulla potentiates swim stress-induced analgesia in formalin test.

Shamsizadeh A, Soliemani N, Mohammad-Zadeh M, Azhdari-Zarmehri H - Iran J Basic Med Sci (2014)

Time scores of nociceptive behaviours induced by formalin (mean ±SEM of 9-10 rats per group) following swim stress measured every 3 min for 90 min (A) and bar chart for formalin test after swim stress in 50-cm high water and control group (B). The columns represent the mean of nociceptive score in each phase: phase 1 (min 1–7), interphase (min 8–14) and phase 2A (min 15–60) and phase 2B (min 61–90), (B). * P<0.05; ** P<0.01 and *** P<0.001 in comparison with control group
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016692&req=5

Figure 3: Time scores of nociceptive behaviours induced by formalin (mean ±SEM of 9-10 rats per group) following swim stress measured every 3 min for 90 min (A) and bar chart for formalin test after swim stress in 50-cm high water and control group (B). The columns represent the mean of nociceptive score in each phase: phase 1 (min 1–7), interphase (min 8–14) and phase 2A (min 15–60) and phase 2B (min 61–90), (B). * P<0.05; ** P<0.01 and *** P<0.001 in comparison with control group
Mentions: Swim stress potentiated the antinociceptive response in phase 1 [T(1, 14)=2.90; P=0.011; (Figure 2B)], interphase [T (1, 14)=3.214; P=0.001; (Figure 2B)], and phase 2A [T (1, 14)=3.074; P=0.008; (Figure 2B)], and had pronociceptive effect on phase 2B [T (1, 14)=2.751; P=0.021; (Figure 2B)].

Bottom Line: For permanent lesion of RVM, R-SKF38393 was injected into the RVM.Forced swim stress in water was employed in adult male rats.Furthermore, R-SKF38393 had pronociceptive effects in phase2B whereas injections of R-SKF38393 resulted in significant difference in nociceptive bahaviours in all phases of formalin test (P<0.05).

View Article: PubMed Central - PubMed

Affiliation: Physiology-Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran.

ABSTRACT

Objective(s): There are many reports about the role of rostral ventromedial medulla (RVM) in modulating stress-induced analgesia (SIA). In the previous study we demonstrated that temporal inactivation of RVM by lidocaine potentiated stress-induced analgesia. In this study, we investigated the effect of permanent lesion of the RVM on SIA by using formalin test as a model of acute inflammatory pain.

Materials and methods: Three sets of experiments were conducted: (1) Application of stress protocol (2) Formalin injection after exposing the animals to the swim stress (3) Either the relevant vehicle or dopamine receptor 1 (D1) agonist R-SKF38393 was injected into the RVM to cause a lesion. For permanent lesion of RVM, R-SKF38393 was injected into the RVM. Forced swim stress in water was employed in adult male rats. Nociceptive responses were measured by formalin test (50µl injection of formalin 2% subcutaneously into hind paw) and pain related behaviors were monitored for 90 min.

Results: In the unstressed rats, permanent lesion of the RVM by R-SKF38393 decreased formalin-induced nociceptive behaviors in phase 1, while in stressed rats, injection of R-SKF38393 into the RVM potentiated swim stress-induced antinociception in phase 1 and interphase, phase 2A of formalin test. Furthermore, R-SKF38393 had pronociceptive effects in phase2B whereas injections of R-SKF38393 resulted in significant difference in nociceptive bahaviours in all phases of formalin test (P<0.05).

Conclusion: The result of the present study demonstrated that permanent inactivation of RVM can potentiate stress-induced analgesia in formalin test.

No MeSH data available.


Related in: MedlinePlus