ABSTRACT
There are differences in individual cardiovascular responses to the administration of dexmedetomidine, a highly selective α-adrenergic receptor (ADRA2A) agonist. The aim of this study was to investigate ADRA2A gene polymorphisms in the Chinese Han population and their association with the cardiovascular response to intravenous dexmedetomidine infusion. Sixty elective surgery patients of Chinese Han nationality were administered 1 µg/kg dexmedetomidine intravenously over 10 min as a premedication. ADRA2A C-1291G and A1780G polymorphism status was determined in these patients, and their relationships to changes in blood pressure and heart rate after dexmedetomidine administration were analyzed. There were neither significant differences in systolic or diastolic blood pressure changes in individuals with different A1780G and C-1291G genotypes after dexmedetomidine administration, nor in heart rates among the different A1780G genotypes. However, there were significant differences in changes in heart rates in patients with different C-1291G genotypes. There were no significant differences in the sedative effects of dexmedetomidine among different A1780G and C-1291G genotypes. Logistic regression revealed that the C-1291G polymorphism was associated with differential decreases in heart rate after intravenous infusion of dexmedetomidine. These findings indicate that the ADRA2A C-1291G polymorphism can affect heart rate changes in patients after intravenous infusion of dexmedetomidine.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate effect of tramadol on c-fos expression in spinal cord dorsal horn and serum IL-6 levels induced by plantar incision in rats.</p><p><b>METHODS</b>The Brennan pain model was induced by incision on the planter surface of left hind paw in rats. Forty-eight rats were randomly divided into six groups: Sham group (Group C), control group (Group I,pretreatment with saline 5 ml), three tramadol pretreatment groups (Group T1, T10 and T20,pretreated with 1 mg/kg, 10 mg/kg and 20 mg/kg tramadol, respectively) and one tramadol treatment group (Group PT10, treated with tramadol 10 mg/kg immediately after operation). Pain behavior was assessed by withdrawal threshold to von Frey filament stimulation intensity, response latency of the hind paw to radiant thermal and a cumulative pain score 2 h after incision. Fos-positive neurons in spinal cord were identified by the immunohistochemical technique. Serum IL-6 levels were measured by enzyme-linked immunosorbent assay (ELISA).</p><p><b>RESULTS</b>WithdrawIal threshold to von Frey filament stimulation intensity and response latency of the hind paw to radiant thermal in Group I were significantly lower than those in Group C (P<0.01). Cumulative pain score in Group I was significantly higher than that in Group C (P<0.01). In Groups of T10 and T20, withdrawal threshold to von Frey filament stimulation intensity and response latency of the hind paw to radiant thermal were significantly higher than those in Group I (P<0.01), cumulative pain score was significantly lower than that in Group I in a dose-dependent manner (P<0.01), and were also those in Group PT10. The greatest density of Fos-positive neurons was located in lamine I-II in Group I. Serum IL-6 levels were significantly elevated in Group I. Pretreatment with tramadol showed a dose-depended inhibitory effect on c-fos expression and serum IL-6 production,but not in Group T1. Administration of tramadol postoperatively also suppressed the c-fos expression and serum IL-6 production as showed in PT10 but were weaker than those in Group T10.</p><p><b>CONCLUSION</b>Pretreatment with tramadol can produce dose-dependent inhibitory effect on c-fos expression in spinal cord dorsal horn and then suppress the inflammatory response to the trauma.</p>
Subject(s)
Animals , Male , Rats , Analgesics, Opioid , Pharmacology , Therapeutic Uses , Interleukin-6 , Blood , Pain Threshold , Pain, Postoperative , Drug Therapy , Metabolism , Posterior Horn Cells , Metabolism , Proto-Oncogene Proteins c-fos , Metabolism , Random Allocation , Rats, Sprague-Dawley , Tramadol , Pharmacology , Therapeutic UsesABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effects of tramadol on the proinflammatory responses in a rat model of incisional pain by investigating its effects on nociceptive thresholds and serum interleukin-6 (IL-6) and IL-2 levels.</p><p><b>METHODS</b>Forty-two male Sprague-Dawley (SD) rats scheduled for plantar incision were randomly divided into 7 groups (n=6 in each group). Rats in Group 1 receiving general anesthesia with no incision were served as control; At 30 min before skin incision, Groups 2 to approximately 5 were given 5 ml normal saline or 1, 10, and 20 mg/kg tramadol, respectively, intraperitoneally (i.p.); Group 6 received 10 mg/kg tramadol after operation; Group 7 received 10 mg/kg tramadol before incision, followed by 200 microg/kg naloxone after operation. Mechanical allodynia was measured by electronic von Frey filament to evaluate the nociceptive thresholds 1 h before incision, and 1 h and 2 h after operation. Serum IL-6 and IL-2 levels were measured by enzyme-linked immunosorbent assay (ELISA) 2 h after operation.</p><p><b>RESULTS</b>Mechanical thresholds decreased significantly and serum IL-6 level increased significantly after operation in Group 2 compared with control (P<0.01), and these changes were reversed respectively by tramadol in a dose-dependent manner (P<0.05 and P<0.01, respectively). IL-2 level remained unchanged after operation in Group 2, but decreased in Group 3 (P<0.05), then gradually returned to the normal level in Groups 4 and 5. The intraperitoneally injected tramadol (10 and 20 mg/kg) produced a potent and dose-dependent antinocicptive effect on the lesioned paw. The antinocicptive effects of tramadol were partially antagonized by naloxone (200 microg/kg), suggesting an additional non-opioid mechanism.</p><p><b>CONCLUSION</b>The results suggest that tramadol could be a good choice for the treatment of pain under the conditions that immunosuppression may be particularly contraindicated.</p>