Tufan Mert1, Hafize Oksuz2, Berin Tugtag3, Metin Kilinc4, Nimet Senoglu2, Ramazan Bilgin5. 1. Department of Biophysics, School of Medicine, Kahramanmaras Sutcu Imam University, Kahramanmaras, Turkey. Electronic address: tufanmert@yahoo.com. 2. Anaesthesiology and Reanimation, School of Medicine, Kahramanmaras Sutcu Imam University, Kahramanmaras, Turkey. 3. Department of Anatomy, School of Medicine, Fatih University, Istanbul, Turkey. 4. Biochemistry, School of Medicine, Kahramanmaras Sutcu Imam University, Kahramanmaras, Turkey. 5. Arts and Science Faculty, Department of Chemistry (Biochemistry Division), University of Cukurova, Adana, Turkey.
Abstract
BACKGROUND: In this study, we investigated the effects of locally (intraplantar) applied remifentanil, a μ opioid receptor agonist, to the paws and tested whether locally N-methyl d-aspartate (NMDA) receptors agonist or antagonist can modify remifentanil-induced effects in diabetic rats. METHODS: Effects of locally (intraplantar) remifentanil, NMDA and MK801 or their combinations were investigated by measuring the latencies, thresholds and two biochemical parameters (malondialdehyde (MDA) and nitric oxide (NO)), in streptozotocin induced diabetic rats. RESULTS: Diabetic rats exhibited hyperalgesia and allodynia and remifentanil treatment aggravated the hyperalgesia and allodynia. The hyperalgesic and allodynic effects of remifentanil decreased in diabetic rats as compared to healthy rats. MK801 suppressed the hyperalgesic and allodynic actions of remifentanil in diabetic rats. However, hyperalgesic and allodynic actions of NMDA increased in diabetic rats. In contrast to age matched group, the combination of NMDA and remifentanil did not produce synergistic actions in diabetic rats. The levels of MDA and NO in the paw tissues of the diabetic rats significantly increased. MK801 significantly decreased NO levels, but not MDA, in diabetic rats. CONCLUSIONS: The hyperalgesic and allodynic actions of locally treated remifentanil may decrease in diabetic conditions. Increases in NMDA receptors activation, reactive oxygen species production and NO release may modify the sensitivity to remifentanil in diabetes induced neuropathic pain states.
BACKGROUND: In this study, we investigated the effects of locally (intraplantar) applied remifentanil, a μ opioid receptor agonist, to the paws and tested whether locally N-methyl d-aspartate (NMDA) receptors agonist or antagonist can modify remifentanil-induced effects in diabeticrats. METHODS: Effects of locally (intraplantar) remifentanil, NMDA and MK801 or their combinations were investigated by measuring the latencies, thresholds and two biochemical parameters (malondialdehyde (MDA) and nitric oxide (NO)), in streptozotocin induced diabeticrats. RESULTS:Diabeticrats exhibited hyperalgesia and allodynia and remifentanil treatment aggravated the hyperalgesia and allodynia. The hyperalgesic and allodynic effects of remifentanil decreased in diabeticrats as compared to healthy rats. MK801 suppressed the hyperalgesic and allodynic actions of remifentanil in diabeticrats. However, hyperalgesic and allodynic actions of NMDA increased in diabeticrats. In contrast to age matched group, the combination of NMDA and remifentanil did not produce synergistic actions in diabeticrats. The levels of MDA and NO in the paw tissues of the diabeticrats significantly increased. MK801 significantly decreased NO levels, but not MDA, in diabeticrats. CONCLUSIONS: The hyperalgesic and allodynic actions of locally treated remifentanil may decrease in diabetic conditions. Increases in NMDA receptors activation, reactive oxygen species production and NO release may modify the sensitivity to remifentanil in diabetes induced neuropathic pain states.