Rat Model Of Incisional Research Articles

Proline-Rich Peptide Mimics Effects of Enamel Matrix Derivative on Rat Oral Mucosa Incisional Wound Healing.

Proline-rich peptides have been shown to promote periodontal regeneration. However, their effect on soft tissue wound healing has not yet been investigated. The aim of this study is to evaluate the effect of enamel matrix derivative (EMD), tyrosine-rich amelogenin peptide (TRAP), and a synthetic proline-rich peptide (P2) on acute wound healing after a full-thickness flap procedure in an incisional rat model. This experimental study has a split-mouth, randomized, placebo-controlled design. Test and control wounds were created on the palatal mucosa of 54 Sprague-Dawley rats. Wounds were histologically processed, and reepithelialization, leukocyte infiltration, and angiogenesis were assessed at days 1, 3, and 7 post-surgery. EMD and P2 significantly promoted early wound closure at day 1 (P <0.001 and P = 0.004, respectively). EMD maintained a significant acceleration of reepithelialization at day 3 (P = 0.004). Wounds treated by EMD and P2 showed increased angiogenesis during the first 3 days of healing (P = 0.03 and 0.001, respectively). Leukocyte infiltration was decreased in EMD-treated wounds at day 1 (P = 0.03), and P2 and TRAP induced a similar effect at days 3 (P = 0.002 and P <0.0001, respectively) and 7 (P = 0.005 and P <0.001). EMD and P2 promoted reepithelialization and neovascularization in full-thickness surgical wounds on rat oral mucosa.

Changes in levels of motilin in duodenum in a rat model of incisional pain

Objective To evaluate the changes in the levels of motilin in the duodenum in a rat model of incisional pain.Methods Eighty-four healthy male Sprague-Dawley rats,aged 6-8 months,weighing 180-220 g,were randomized into 2 groups (n =42 each) using a random number table:control group (group C) and incisional pain group (group P).The animals were anesthetized with sevoflurane.In group P,a 1 cm long incision was made in the plantar surface of right hindpaw.Six rats were chosen from each group and mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 24 h before operation (T0) and 1,6,24,48 and 72 h after operation (T1-5).Six rats were chosen from each group at T0-5 and sacrificed and the duodenal mucosal tissue was prepared for measurement of motilin levels by ELISA.Pearson linear correlate analysis was performed between the motilin level and pain threshold at each time point in group P.Results Compared with group C,MWT was significantly decreased,TWL was shortened,and motilin levels were significantly increased at T1-4,and no significant change was found at T0 and T5 in group P.The motilin levels were negatively correlated with MWT (r =-0.8 910) and TWL (r =-0.8 463) in group P.Conclusion Incisional pain can promote the secretion of motilin in the duodenum. Key words: Pain, postoperative ; Motilin; Duodenum

Relationship between function of spinal NMDA receptors and delta opioid receptors in a rat model of incisional pain-remifentanil-induced hyperalgesia

Objective To investigate the relationship between the function of spinal NMDA receptors and δ opioid receptors in a rat model of incisional pain-remifentanil-induced hyperalgesia.Methods Thirty male Sprague-Dawley rats,aged 2-3 months,weighing 260-280 g,in which intrathecal catheters were successfully implanted or in which the catheter was successfully placed via the caudal vein,were randomly divided into 3 groups (n =10 each) uisng a random number table:control gourp (group C),remifentanil + incisional pain group (group RI),and δ opioid receptor inhibitor naltrindole group (group NI).A 1-cm longitudinal incision was made through skin,fascia and muscle of the plantar aspect of the hindpaw in chloral hydrate-anesthetized rats.In group C,normal saline 0.1 ml· kg-1 · min-1 was infused via the caudal vein for 60 min.In group RI,remifentanil 1.0 μg· kg-1 · min-1 was infused via the caudal vein for 60 min,and the model of incisional pain was established immediately at the beginning of infusion.In group NI,naltrindole 30 nmol (10 μl) was administrated intrathecally,then remifentanil was infused for 60 min at a rate of 1.0 μg· kg-1 · min-1 and the model of incisional pain was established immediately at the beginning of infusion.At 24 h before normal saline or remifentanil infusion and 2,6,24 and 48 h after the end of infusion (T0-4),mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured.The rats were sacrificed after the last behavioral test.L4-6 segments of the spinal cords were removed for determination of NMDA receptor expression in total and membrane protein using Western blot analysis.The ratio of NMDA receptor expression in membrane protein to that in total protein (m/t ratio) was calculated.Results Compared with the basline value at T0,MWT was significantly decreased,and TWL was shortened at T1-4 in RI and NI groups.MWT was gradualy decreased,and TWL was gradualy shortened at T1-3 and no significant difference was found between MWT and TWL at T3 and T4 in RI and NI groups.Compared with group C,MWT was significantly decreased,and TWL was shortened at T1-4,the expression of NR1-and NR2B-containing NMDA receptors in total and membrane protein was down-regulated,and m/t ratio was decreased in group NI.Conclusion Activation of δ opioid receptors can enhance the function of NR1-and NR2B-containing NMDA receptors,which may be involved in the development of incisional pain-remifentanil-induced hyperalgesia in rats. Key words: Piperidines; Hyperalgesia; Receptors, opioid, delta; Receptors, N-methyl-D-aspartate ; Spinal cord

Changes in expression of NRF-1 in spinal cord during remifentail-induced hyperalgesia in a rat model of incisional pain

Objective To evaluate the changes in the expression of NRF-1 in the spinal cord during remifentail-induced hyperalgesia in a rat model of incisional pain.Methods Forty-eight Sprague-Dawley rats,weighing 180-220 g,were randomly divided into 4 groups (n =12 each) using a random number table:control group (C); incisional pain group (group Ⅰ); remifentanil group (group R); incisional pain + remifentanil group (group Ⅰ + R).All the rats were anesthetized with sevoflurane.A 1-cm longitudinal incision was made through skin,fascia and muscle of the plantar aspect of the right hindpaw in I and I + R groups.In C and I groups,normal saline was subcutaneously infused for 30 min.In group I + R,remifentanil (0.04 mg/kg,0.4ml) was subcutaneously infused for 30 min starting from the onset of skin incision.Paw withdrawal threshold to mechanical stimulation (PWMT) was measured at 24 h before operation and at 2,6,12,24 and 48 h after operation.After measurement of PWMT at 48 h,the rats were sacrificed and L4,5 segments of the spinal cord were removed rapidly to detect the expression of nuclear respiratory factor 1 (NRF-1) by immunofluorescence and Western blot.Results Compared with group C,PWMT was significantly decreased at each time point after operation,and the expression of NRF-1 in the spinal cord was up-regulated in I and I + R groups (P ＜ 0.05).Compared with group I,PWMT was significantly decreased at each time point after operation,and the expression of NRF-1 in the spinal cord was up-regulated in group I + R (P ＜ 0.05).Conclusion Up-regulation of NRF-1 expression in the spinal cord may be involved in the development of remifentail-induced hyperalgesia in a rat model of incisional pain. Key words: Piperidines; Hyperalgesia; Spinal cord; Nuclear respiratory factor 1

Effect of transient receptor potential A1 antagonists on post-operation pain in a rat model of incisional pain

Objective To investigate the effect of intrathecal and intraplantar injection of transient receptor potential A1 (TRPA1) antagonists on post-operation pain in a rat model of incisional pain.Methods Seventy-two adult male Sprague-Dawley rats weighing 200-250 g were randomly divided into 6 groups (n =12):control group (group C),incision group (Ⅰ group).intrathecal injection of DMSO group (DMSO1 group),intraplantar injection of DMSO group (DMSO2 group),intrathecal injection of HC-030031 group (H1 group),intraplantar injection of HC-030031 group (H2 group).Rats in Ⅰ,DMSO1,DMSO2,H1,and H2 groups were operated with incision.Intrathecal or intraplantar injections were performed 24 h after operation.The rats in DMSO1 and H1 groups were respectively intrathecally injected with 10％ DMSO (20 μl) and HC-030031 (50 μg).DMSO2 and H2 groups were respectively intraplantarlly injected with 10％ DMSO (40 μ l) and HC-030031 (100 μg).The paw withdrawal mechanical threshold (PWMT) was measured at 1 h before injection (T0),and 0.5 h (T1),1.0 h (T2),2.0 h (T3),4.0 h (T4) and 6.0 h (T5) after intrathecal or intraplantar injections.Four SD rats in each group were sacrificed at T4 and the segments of the spinal cord were obtained for determination of TRPA1 expression in the spinal cord by using Western blotting.Results As compared with C group [(34.4 ± 4.7) g] and Ⅰ group [(23.8 ±4.3) g],PWMT was significantly decreased and the expression of TRPA1 was up-regulated in DMSO1 and DMSO2 groups at T4 in spinal dorsal horn.The PWMT in H1 group [(28.3 ± 2.4) g] and H2 group [(29.1 ±4.2) g] was increased and the expression of TRPA1 was down-regulated at T4 as compared with DMSO1 group [(24.6 ±3.5) g] and DMSO2 group [(22.1 ±4.7) g].Conclusion Intrathecal or intraplantar administration with TRPA1 antagonists could attenuate incisional pain in rats. Key words: Incisional pain; Spinal cord; Transient receptor potential A1

Changes in expression of GluR1-containing AMPA receptor and GluR2-containing AMPA receptor in spinal dorsal horn in a rat model of incisional pain-remifentanil-induced hyperalgesia

Objective To investigate the changes in the expression of GluR1-containing AMPA receptor and GluR2-containing AMPA receptor in spinal dorsal horn in a rat model of incisional pain-remifentanil-induced hyperalgesia.Methods Thirty-two male Sprague-Dawley rats,aged 2-3 months,weighing 240-260 g,in which the catheter was successfully inserted into the caudal vein,were randomly divided into 4 groups (n =8 each):control gourp (group C),remifentanil group (group R),incisional pain group (group P),and remifentanil + incisional pain group (group R + I).A 1-cm longitudinal incision was made through skin,fascia and muscle of the plantar aspect of the left hindpaw in chloral hydrate-anesthetized rats.Remifentanil 1.0 μg· kg-1 · min-1 was infused intravenously for 1 h sarting from beginning of establishment of incisional pain model.Paw withdrawal threshold (PWT) to yon Frey hair stimulation and paw withdrawal latency (PWL) to thermal stimulation were measured before remifentanil infusion and at 2,6,24 and 48 h after remifentanil infusion.The rats were sacrificed after the last behavioral test and L4-6 segments of the spinal cord were removed for determination of the expression of AMPA receptor GluR1 and GluR2 subunits in total and membrane protein in the dorsal horn of spinal cord by Western blot.The ratio between the expression of GluR1 and GluR2 subunits in membrane protein (GluR1/GluR2) was calculated.Results Compared with group C,PWL was significantly shortened,PWT was decreased,the expression of GluR1 in total and membrane protein was up-regulated,the expression of GluR2 in total and membrane protein was down-regulated,and GluR1/GluR2 ratio was increased in I,R and R + I groups (P ＜ 0.05).Compared with R and I groups,PWL was significantly shortened,PWT was decreased,the expression of GluR1 in total and membrane protein was up-regulated,the expression of GluR2 in total and membrane protein was down-regulated,and GluR1/GluR2 ratio was increased in group R + I (P ＜ 0.01).Conclusion Increased percentage of GluR1-conraining AMPA receptors in membrane protein induced by up-regulation of expression of GluR1-containing AMPA receptor and down-regulation of expression of GluR2-containing AMPA receptor in total and membrane protein is involved in the development of incisional pain-remifentanil-induced hyperalgesia in rats. Key words: Receptors, AMPA; Piperidines; Hyperalgesia; Pain; Spinal cord

Changes in total and surface N-methyl-D-aspartate receptor NR1, NR2A and NR2B subunits in spinal cord in a rat model of incisional pain-remifentanil-induced hyperalgesia

Objective To investigate the changes in total and surface N-methyl-D-aspartate receptor (NMDAR) NR1,NR2A and NR2B subunits in spinal cord in a rat model of incisional pain(IP)-remifentanil-induced hyperalgesia.Methods Thirty-two male SD rate in which caudal vein catheter were successfully placed were randomly divided into 4 groups ( n =8 each):control group(group C),remifentanil group(group R),IP group (group I) and IP + remifentanil group (group R + I).In groups R and C remifentanil 1.2 μg· kg-1 · min-1 or the same volume of normal saline was infused intravenously for60 main.In groups R + I and I,a 1 cm longitudinal incision was made in the plantar surface of left hindpaw and remifentanil 1.2 μg· kg-1 ·min-1 or the same volume of normal saline was infused intravenously for 60 min.Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured at 24 h before and 2,6,24,48 h after remifentanil or normal saline administration.The animals were sacrificed after last pain threshold measurement.The L4-6 segment of the spinal cord was isolated for determination of the expression of the total and surface NMDAR NR1,NR2A and NR2B subunits in spinal cord by Western blot.The ratio of surface NR2B/NR2A was calculated.Results Compared with group C,PWT was significantly decreased,PWL shortened,the expression of the total and surface NMDAR NR1,NR2A and NR2B subunits up-regulated and the ratio of surface NR2B/NR2A increased in groups 1,R and R + I( P ＜ 0.05).Compared with groups R and I,PWT was significantly decreased,PWL shortened,the expression of the total and surface NMDAR NR1,NR2A and NR2B subunits up-regulated and the ratio of surface NR2B/NR2A increased in group R + I( P ＜ 0.05).There was no significant difference in the total and surface NMDAR NR2A subunits among the four groups( P ＞ 0.05).Conclusion The up-regulation of total and surface NMDAR NR1 and NR2B subunits and the increased percentage of surface NR2B subunits in rats spinal cord may be involved in the development of incisional pain- remifentanil- induced hyperalgesia. Key words: Piperidines; Hyperalgesia; Receptors, N-methyl-D-aspartate; Spinal cord

Effect of dexmedetomidine on norepinephrine release in midbrain periaqueductal gray in a rat model of incisional pain

Objective To investigate the effect of dexmedetomidine on norepinephrine(NE)release in midbrain periaqueductal gray(PAG)in a rat model of incisional pain.Methods Twenty-four male Wistar rats in which microdialvsis catheter was successfully placed in the ventrolateral region of PAG without complications were randomly divided into 4 groups(n=6 each):group control(group C);group incisional pain(group IP);group dexmetomidine(group D)and group dexmedetomidine+yohimbine(group DY).Incisional pain was induced by an incision made into the plantar surface of left hindpaw in IP,D,DY groups.Dexmedetomidine 30 μg/kg and dexmedetomidine 30 μg/kg+yohimbine 0.5 mg/kg were given intraperitoneally at 15 min before plantar incision in group D and group DY respectively.Mechanical paw withdrawal threshold(MWT)to von Frey filament stimulation was measured at 30 min before(baseline)and 1,2,3,4 h after operation in C,IP,D groups,and at 30 min before(baseline),and 1 h after operation in group DY.Dialysate samples were collected at 30 min before(baseline)and at evcry 30 min after operation for 4 h via cerebral microdialysis catheter for determination of the NE concentration in C,IP,D groups,and at 30 min before(baseline),30,60 min after operation in group DY.Results Incisional pain significantly decreased MWT and increased the NE concentration in dialysate in group IP.Dexmedetomidine premedication significantly inhibited mechanical hyperalgesia and attenuated incisional pain-induced increase in the NE concentration in dialysate in group D.Yohimbine counteracted effects of dexmedetomidine.Conclusion Dexmedetomidine has analgesic effect though inhibition of NE release from PAG. Key words: Dexmedetomidine; Pain; Mesencephalon; Cerebral aqueduct; Norepinephrine

Effects of dexmedetomidine on remifentanil-induced hyperalgesia in a rat model of incisional pain

Objective To observe the effects of pretreatment of dexmedetomidine(DEX)on remifentanilinduced hyperalgesia in a rat model of incisional pain.Methods Sixty male SD rats were randomly divided into five groups:C group(control),I group(incisional pain),R group(remifentanil+incisional pain),ID group(incisional pain+DEX),RD group(remifentanil+incisional pain+DEX).ID and RD group were administered subcutaneously DEX 50μg/kg at ten minutes before anesthesia with sevoflurane.All groups except C group needed to be made the model of incisional pain.A 1 cm long incision was made through skin and fascia of the plantar aspect of the foot.The skin was apposed with 2 mattress sutures.At 24 hours before operation(T0),6 hours(T1),24 hours(T2)and 48 hours(T3)after operation respectively.Paw Withdrawal Thermal latency(PWTL)and Paw Mechanical Withdrawal Threshold(PMW)were detected on the rats' right hind paw in all groups.Results At T1,T2,T3,compared with I group((7.70±0.67)g,(10.79±1.83)g,(10.97±1.87)g),the PMW of R group ((3.72±0.71)g,(6.54±1.27)g,(7.27±1.53)g)were significantly longer(P＜0.05);compared with I group((20.74±2.72)s,(16.56±1.38)s,(22.55±2.01)s),the PWTL of R group((11.81±2.52)s,(11.27 ±2.30)s,(12.30±2.21)s)were significantly longer(P＜0.05).Compared with I group,the PMW of ID group were only significantly longer(P＜0.05)at T1((11.57±2.48)g).Compared with R group,the PMW of RD group were significantly longer at T1((14.03±1.01)g),T2((14.27±1.33)g),T3((14.26±1.58)g)(P＜0.05)and the PWTL of RD group were significantly longer at T1((23.56±1.53)s),T2((16.54±3.24)s)(P＜0.05).Conclusion In a rat model of incisional pain,remifentanil could induce hyperalgesia,and dexmedetomidine could prevent the remifentanil-induced hyperalgesia. Key words: Dexmedetomidine; Remifentanil; Hyperalgesia; Incisional pain; Rat

Comparison of wound-bursting strengths and surface characteristics of FDA-approved tissue adhesives for skin closure

We compared the wound-bursting strength (WBS), mode of adhesive failure and surface characteristics of two FDA-approved tissue adhesives for skin closure in an incisional rat model using a randomized, controlled, blind animal experiment. Standardized 2-cm full-thickness incisions were made in duplicate on both sides of 15 rats and closed with Indermil, or High Viscosity Dermabond (HVD) following manufacturers' instructions. WBS was measured 5 min later with a validated commercial instrument. Wound sections were also observed under light and scanning electron microscopies. Indermil was significantly weaker than HVD (mean difference, 143 mmHg; 95% CI, 42-229 mmHg, P = 0.002). The mode of failure for Indermil was primarily cohesive in the adhesive and the primary failure mode for the HVD was interfacial (χ2, P < 0.01). Microscopic observations demonstrated that application of HVD resulted in a thick, uniform and smooth surface while Indermil resulted in a thin, irregular, cracked surface. We conclude that HVD is stronger, thicker and more uniform than Indermil.

Diphenylhydantoin sodium promotes early and marked angiogenes is and results in increased collagen deposition and tensile strength in healing wounds

Background. Sodium diphenylhydantoin (DpH) (phenytoin) was first introduced as an antiepileptic in 1938. One of its side effects, gingival hyperplasia, prompted investigation into the possible application of this drug as a promoter of wound healing. Since the late 1950s phenytoin has been used in a variety of clinical situations. However, its exact mechanism of action is still debated. The aim of this study was to determine the effect ofDpH on wound healing in an incisional rat model. Methods. A four dorsal wound model was used, and each cephalad wound had a polyvinyl alcohol sponge placed in a subcutaneous pocket just above its cephalad end. Caudal and cephalad wounds were treated with 10 mg DpH in 200 μl carrier, and the other two wounds received an equal volume of the saline vehicle as controls on the day of wounding and on the third and sixth postoperative days. The animals were killed on the tenth postwounding day. Tensile strength of fresh and fixed scars was determined using constant speed tensiometry, and wound hydroxyproline was determined spectophotometrically. Results. There was a highly significant increase in both fresh and fixed wound tensile strength of all DpH-treated wounds compared with controls (p < 0. 001). This was reflected by a significant increase in polyvinyl alcohol sponge hydroxyproline in DpH-treated wounds compared with saline-treated wounds (p = 0. 002). Histologic examination of these wounds was performed at 3 and 6 days after wounding. There was moderate fibroblast infiltration with a marked inflammatory infiltrate and neovascularization in the DpH-treated wounds compared with controls at 3 days. By day 6, the inflammatory infiltrate had almost totally receded in the treated wounds, but fibroblast infiltration and angiogenesis were still persistently marked. In comparison, the saline-treated wounds still had moderate inflammatory and fibroblast infiltrate and mild angiogenesis. Conclusions. DpH alters the natural course of wound healing and may be of benefit in clinical situations where defective wound collagen deposition may lead to poor wound healing and consequent morbidity and mortality.

Diphenylhydantoin sodium promotes early and marked angiogenes is and results in increased collagen deposition and tensile strength in healing wounds

Background: Sodium diphenylhydantoin (DpH) (phenytoin) was first introduced as an antiepileptic in 1938. One of its side effects, gingival hyperplasia, prompted investigation into the possible application of this drug as a promoter of wound healing. Since the late 1950s phenytoin has been used in a variety of clinical situations. However, its exact mechanism of action is still debated. The aim of this study was to determine the effect of DpH on wound healing in an incisional rat model. Methods: A four dorsal wound model was used, and each cephalad wound had a polyvinyl alcohol sponge placed in a subcutaneous pocket just above its cephalad end. Caudal and cephalad wounds were treated with 10 mg DpH in 200 μl carrier, and the other two wounds received an equal volume of the saline vehicle as controls on the day of wounding and on the third and sixth postoperative days. The animals were killed on the tenth postwounding day. Tensile strength of fresh and fixed scars was determined using constant speed tensiometry, and wound hydroxyproline was determined spectophotometrically. Results: There was a highly significant increase in both fresh and fixed wound tensile strength of all DpH-treated wounds compared with controls ( p < 0.001). This was reflected by a significant increase in polyvinyl alcohol sponge hydroxyproline in DpH-treated wounds compared with saline-treated wounds ( p = 0.002). Histologic examination of these wounds was performed at 3 and 6 days after wounding. There was moderate fibroblast infiltration with a marked inflammatory infiltrate and neovascularization in the DpH-treated wounds compared with controls at 3 days. By day 6, the inflammatory infiltrate had almost totally receded in the treated wounds, but fibroblast infiltration and angiogenesis were still persistently marked. In comparison, the saline-treated wounds still had moderate inflammatory and fibroblast infiltrate and mild angiogenesis. Conclusions: DpH alters the natural course of wound healing and may be of benefit in clinical situations where defective wound collagen deposition may lead to poor wound healing and consequent morbidity and mortality. (Surgery 1998;123:287-93.)