Sule Aydin

Valnoctamide: The effect on relieving of neuropathic pain and possible mechanisms

Abstract The purpose of this study is to assess the possible anti‐allodynic and antihyperalgesic effect of valnoctamide, an amide derivative of valproic acid, at the doses of 40, 70 and 100 mg/kg (i.p.) in neuropathic pain model induced by chronic constriction injury in rats, by using dynamic plantar test and plantar test (Hargreaves method), and to evaluate that the possible role of certain serotonin, noradrenergic, opioid and GABAergic receptors by pre‐treatment with 1 mg/kg (i.p.) ketanserin, yohimbine, naloxone and 0.5 mg/kg (i.p.) bicuculline, respectively. 70 and 100 mg/kg valnoctamide significantly increased the mechanical and thermal thresholds decreasing with the development of neuropathy and demonstrated anti‐allodynic and antihyperalgesic activity. Limited contribution of serotonin 5‐HT2A/2C receptors and &agr;2‐adrenoceptors, and significant contribution of GABAA and opioid receptors to the anti‐allodynic activity have been identified whereas remarkable contribution of opioid receptors and significant contribution of serotonin 5‐HT2A/2C receptors, &agr;2‐adrenoceptors, GABAA receptors to the antihyperalgesic activity have been identified. Based upon these findings and considering that valnoctamide has safer side‐effect profile, it is possible to say that valnoctamide is a potential agent that might be used alone or in combination with the other effective therapies in the alleviating of neuropathic pain.

Comparison of the effects of curcumin, tramadol and surgical treatments on neuropathic pain induced by chronic constriction injury in rat

AIM Nerve entrapment syndromes are the most common causes of neuropathic pain. Surgical decompression is the preferred method of treatment. The aim of this study was to compare the efficacy of curcumin, tramadol and chronic constriction release treatment (CCR), individually or together, in a rat model of sciatic nerve injury. MATERIAL AND METHODS Eighty male rats were divided into eight study groups. Group 1 was the sham group. Group 2 was the control group with established chronic constriction injury (CCI). CCI was also established in Groups 3?8. Group 3 underwent chronic constriction release (CCR). Groups 4 and 5 received curcumin and tramadol. Groups 6 and 7 also received curcumin (100 mg/kg daily, oral) and tramadol (10 mg/kg daily, intraperitoneal, 14 days) after CCR, respectively. Combined curcumin-tramadol treatment was applied to Group 8. Behavioral tests (thermal hyperalgesia, dynamic plantar, cold plate test) were performed on days 0,3,7,13,17, and 21. Tissue tumor necrosis factor-? (TNF-?) and interleukin-10 (IL-10) levels were analyzed in the nerve and dorsal root ganglion (DRG) samples on day 21. Histopathological examination was performed on the nervous tissue and DRG. RESULTS Tramadol-CCR and tramadol-curcumin significantly attenuated mechanical allodynia and thermal hyperalgesia. In the CCI-CCR-tramadol treatment group, TNF-? levels were significantly lower in the sciatic nerve tissue, and DRG and IL-10 levels were significantly higher in the sciatic nerve tissue. CONCLUSION CCI-CCR-tramadol treatment is highly effective in the symptomatic treatment of neuropathic pain. CCR-curcumin is associated with less degeneration and high levels of regeneration in the nerve tissue.

Pregabalin Attenuates Carrageenan-Induced Acute Inflammation in Rats by Inhibiting Proinflammatory Cytokine Levels

Objective Pregabalin (PGB) is a compound used in the treatment of epilepsy, anxiety, and neuropathic pain. Experimental data also indicate that PGB can reduce inflammatory pain. We aimed to investigate the anti-inflammatory effects of PGB on carrageenan (CAR)-induced paw edema and its effects on tumor necrosis factor-α (TNF-α) and interleukine-1β (IL-1β) acting as acute phase cytokines in inflammation, and anti-inflammatory cytokine IL-10, in rats. Materials and Methods Single doses of PGB 30, 50, and 100 mg/kg and indomethacin (INDO) 5 mg/kg in the treatment groups and saline in the control group were injected once intraperitoneally prior to administration of 100 μl of 1% CAR into the right hind paw of the rats. The paw thickness was measured using gauge calipers (Vernier calipers) before (0 hour) and every hour afterwards for 6 hours following the inflammation induction. The cytokine levels in the blood serum obtained intracardiacally were determined after 6 hours using the enzyme-linked immunosorbent assay method. p<0.05 was considered statistically significant. Results There was no significant difference between the 0 and 6th hour considering the paw thickness in all groups, except in the CAR group. CAR significantly increased the paw thickness at 6 hours compared to the 0 hour. All doses of PGB and INDO significantly reduced the paw thickness after 6 hours compared to the CAR group. The TNF-α and IL-1β levels in the PGB and INDO groups were comparable to the control group, whereas in the CAR group, these levels were increased. The IL-10 level was enhanced in the PGB 50 mg/kg and INDO groups. Conclusion It was observed that all doses of PGB exerted anti-inflammatory-like effects comparable to INDO, supported by their effects on the levels of cytokines.

The possible mechanisms of protocatechuic acid-induced central analgesia

It is aimed to investigate the central antinociceptive effect of protocatechuic acid and the involvement of stimulation of opioidergic, serotonin 5-HT2A/2C, α2-adrenergic and muscarinic receptors in protocatechuic acid-induced central analgesia in mice. Time-dependent antinociceptive effects of protocatechuic acid at the oral doses of 75, 150 and 300 mg/kg were tested in hot-plate (integrated supraspinal response) and tail-immersion (spinal reflex) tests in mice. To investigate the mechanisms of action; the mice administered 300 mg/kg protocatechuic acid (p.o.) were pre-treated with non-specific opioid antagonist naloxone (5 mg/kg, i.p.), serotonin 5-HT2A/2C receptor antagonist ketanserin (1 mg/kg, i.p.), α2-adrenoceptor antagonist yohimbine (1 mg/kg, i.p.) and non-specific muscarinic antagonist atropine (5 mg/kg, i.p.), respectively. The antinociceptive effect of protocatechuic acid was observed at the doses of 75, 150 and 300 mg/kg in tail-immersion test, at the doses of 150 and 300 mg/kg in hot-plate test at different time interval. The enhancement in the latency of protocatechuic acid-induced response to thermal stimuli was antagonized by yohimbine, naloxone and atropine in tail-immersion test, while it was antagonized only by yohimbine and naloxone pretreatments in hot-plate test. These results indicated that protocatechuic acid has the central antinociceptive action that is probably organized by spinal mediated cholinergic and opiodiergic, also spinal and supraspinal mediated noradrenergic modulation. However, further studies are required to understand how protocatechuic acid organizes the interactions of these modulatory systems. As a whole, these findings reinforce that protocatechuic acid is a potential agent that might be used for pain relief. Additionally, the clarification of the effect and mechanisms of action of protocatechuic acid will contribute to new therapeutic approaches and provide guidance for new drug development studies.

Agmatine co‐treatment attenuates allodynia and structural abnormalities in cisplatin‐induced neuropathy in rats

Cisplatin is a widely used antineoplastic agent in the treatment of various cancers. Peripheral neuropathy is a well‐known side effect of cisplatin and has potential to result in limiting and/or reducing the dose, decreasing the quality of life. Thus, effective treatments are needed. Agmatine is an endogenous neuromodulator that has been shown to exert antiallodynic effects in various animal studies. The first aim of this study was to investigate the in vitro effects of agmatine on cisplatin‐induced neurotoxicity. Primary cultures of dorsal root ganglia (DRG) which are the primary target of drug injury were prepared. DRG cells were incubated with cisplatin (100, 200, 500 μm). Then, agmatine (10, 100, 500 μm) was administered with the submaximal concentration of cisplatin. Cisplatin caused concentration‐dependent neurotoxicity, and agmatine did not alter this effect. The second aim was to investigate the effects of agmatine on cisplatin‐induced peripheral neuropathy in rats and the influence of nitric oxide synthase (NOS) inhibitor, L‐NAME, in this effect. Female Sprague Dawley rats received intraperitoneal saline (control), cisplatin (3 mg/kg), cisplatin+agmatine (100 mg/kg), or cisplatin+agmatine+L‐NAME (10 mg/kg) once a week for 5 weeks. The mechanical allodynia, hot plate, and tail clip tests were performed, and DRG cells and sciatic nerves were analyzed. Agmatine and agmatine+L‐NAME combination attenuated CIS‐induced mechanical allodynia and degeneration in DRG cells and sciatic nerves. However, L‐NAME did not potentiate the antiallodynic or neuroprotective effect of agmatine. These findings indicate that agmatine co‐administration ameliorates cisplatin‐induced neuropathy and may be a therapeutic alternative.

PT670. Antiinflammatory and gastric side effect of gabapentin

Nicotinic acetylcholine (nACh) receptors evoke convulsive seizures both in nicotine intoxication and human epileptic disorders (e.g., autosomal dominant nocturnal frontal lobe epilepsy [ADNFLE]). Here, we performed behavioral and immunohistochemical studies to elucidate the mechanisms of nicotineinduced seizures. Nicotine at high doses (4 mg/kg, i.p.) evoked convulsive seizures, which was antagonized by non-selective (mecamylamine) and α7-selective (methyllycaconitine) nACh receptor antagonists. Nicotine-induced seizures were accompanied by significant and region-specific increments in Fos protein expression, a biological marker of neural excitation, in the piriform cortex (Pir), amygdala (AMG), medial habenular nucleus (MHb), thalamus (Th) and solitary tract, suggesting that these regions are potential causative sites for nicotine-induced seizures. Electrical lesioning (1 mA for 15 sec per side) of AMG significantly suppressed nicotine-induced seizures, whereas neither lesioning of the Pir, MHb nor Th affected the nicotine seizure induction. Furthermore, bilateral microinjection of nicotine (100 or 300 μg/μL/side) into the AMG effectively evoked convulsive seizure in a dose-dependent manner. The present results strongly suggest that acute nicotine treatment evokes convulsive seizures by activating amygdala neurons, mainly through α7nACh receptors. PT668 Development of behavioral dysfunction in mice cohabit with brain disordered cage-mate Seungmoon Jun1, Daejong Jeon2, Yong Jeong1, Hyunwoo Yang1 1Korea Advanced Institute of Science & Technology, Republic of Korea, 2Seoul National University, Republic of Korea Abstract People who live with patients with brain disorders are considered as a potential risk group leading to mental disorder. They suffer from a caregiving burden and distressing situation. Consequently, the longer caregiving, the worse their quality of life. In spite of their devoted effort, caregiver’s deteriorated state has been overlooked. Here, we attempted to set a longterm housing model reflecting the particular situation. Mice were housed with a conspecific temporal lobe epilepsy model mouse or inescapable foot-shock stress mouse models. After long-term housing, cage-mate was performed behavior testsPeople who live with patients with brain disorders are considered as a potential risk group leading to mental disorder. They suffer from a caregiving burden and distressing situation. Consequently, the longer caregiving, the worse their quality of life. In spite of their devoted effort, caregiver’s deteriorated state has been overlooked. Here, we attempted to set a longterm housing model reflecting the particular situation. Mice were housed with a conspecific temporal lobe epilepsy model mouse or inescapable foot-shock stress mouse models. After long-term housing, cage-mate was performed behavior tests and electrophysiological investigation. The conspecific cagemate showed increased anxiety and depression-like behavior. Furthermore, they showed significantly reduced social interaction with juvenile and anesthetized mouse. Behavioral dysfunction of cage-mate sustained four weeks after removing the mouse model. Interestingly, fluoxetine, serotonin selective reuptake inhibitor, hardly restored their behaviors. Our results suggest that a dweller whose cage-mate having brain disorder could develop abnormal behavior including reduced social and increased depression-like behavior. These findings may help to understand psychosocial or psychiatric symptoms frequently observed in at-risk nursing people or caregivers. PT669 Investigation of the antiinflammatory and gastric side effects of pregabalin Fatma Sultan Kilic1, Bilgin Kaygisiz1, Sule Aydin1, Hadi Karimkhani2, Cafer Yildirim1, Setenay Oner3 1 Eskisehir Osmangazi University Medical School, Department of Pharmacology 2 Eskisehir Osmangazi University Medical School, Department of Biochemistry 3 Eskisehir Osmangazi University Medical School, Department of Biostatistics Abstract Objectives: Nonsteroidal antiinflammatory drugs are used for the relief of inflammation, however gastrointestinal side effects restrict their clinical use. We aimed to investigate the antiinflammatory effects of pregabalin, a drug used in epilepsy, anxiety, neuropathic pain treatment, on carrageenaninduced paw edema and to evaluate its gastric side effects in Wistar rats. Methods: Pregabalin 30,50,100mg/kg; indomethacin 5mg/ kg(reference drug), vehicle(saline) were injected intraperitoneally before 100μl of 1% carrageenan administration into the right hind paws of the rats. Paw thickness was measured by a gauge calipers(Vernier Calipers) before (0th hour) and in every hour during 6 hours after induction of inflammation. Paw thickness of treated groups were compared with control group with One-way ANOVA. Also paw thickness in 0th and 6th hours were compared within each group with twoway ANOVA. Pregabalin was administered orally for 10 days to evaluate gastric side effect. At the end of 10 day treatment, rats were sacrificed, gastric tissues were removed out, mucus secretion was determined spectrophotometrically, ulcer index was scored from score 0:(no petechia) to score 3:(petechia>5mm). Results: There was no significant difference between 0th and 6th hours in paw thickness of all groups, except carrageenan group. Carrageenan significantly increased paw thickness in 6th hour compared to 0th hour. All doses of pregabalin and indomethacin significantly reduced paw thickness in 6th hour compared to carrageenan group. Pregabalin 50 and 100mg/kg similar to indomethacin significantly reduced mucus secretion and increased ulcer index compared to control while pregabalin 30mg/kg did not. Conclusion: All doses of pregabalin exerted antiinflammatory effects comparable to indomethacin, 50 and 100mg/kg pregabalin showed gastric side effects as reduced mucus secretion and ulcer formation similar to indomethacin and 30mg/kg pregabalin may be reasonable dose for antiinflammatory effect without showing gastric side effects. This study was supported by ‘Scientific Researchs Projects’ of Eskisehir Osmangazi University.

PT669. Investigation of the antiinflammatory and gastric side effects of pregabalin

Nicotinic acetylcholine (nACh) receptors evoke convulsive seizures both in nicotine intoxication and human epileptic disorders (e.g., autosomal dominant nocturnal frontal lobe epilepsy [ADNFLE]). Here, we performed behavioral and immunohistochemical studies to elucidate the mechanisms of nicotineinduced seizures. Nicotine at high doses (4 mg/kg, i.p.) evoked convulsive seizures, which was antagonized by non-selective (mecamylamine) and α7-selective (methyllycaconitine) nACh receptor antagonists. Nicotine-induced seizures were accompanied by significant and region-specific increments in Fos protein expression, a biological marker of neural excitation, in the piriform cortex (Pir), amygdala (AMG), medial habenular nucleus (MHb), thalamus (Th) and solitary tract, suggesting that these regions are potential causative sites for nicotine-induced seizures. Electrical lesioning (1 mA for 15 sec per side) of AMG significantly suppressed nicotine-induced seizures, whereas neither lesioning of the Pir, MHb nor Th affected the nicotine seizure induction. Furthermore, bilateral microinjection of nicotine (100 or 300 μg/μL/side) into the AMG effectively evoked convulsive seizure in a dose-dependent manner. The present results strongly suggest that acute nicotine treatment evokes convulsive seizures by activating amygdala neurons, mainly through α7nACh receptors. PT668 Development of behavioral dysfunction in mice cohabit with brain disordered cage-mate Seungmoon Jun1, Daejong Jeon2, Yong Jeong1, Hyunwoo Yang1 1Korea Advanced Institute of Science & Technology, Republic of Korea, 2Seoul National University, Republic of Korea Abstract People who live with patients with brain disorders are considered as a potential risk group leading to mental disorder. They suffer from a caregiving burden and distressing situation. Consequently, the longer caregiving, the worse their quality of life. In spite of their devoted effort, caregiver’s deteriorated state has been overlooked. Here, we attempted to set a longterm housing model reflecting the particular situation. Mice were housed with a conspecific temporal lobe epilepsy model mouse or inescapable foot-shock stress mouse models. After long-term housing, cage-mate was performed behavior testsPeople who live with patients with brain disorders are considered as a potential risk group leading to mental disorder. They suffer from a caregiving burden and distressing situation. Consequently, the longer caregiving, the worse their quality of life. In spite of their devoted effort, caregiver’s deteriorated state has been overlooked. Here, we attempted to set a longterm housing model reflecting the particular situation. Mice were housed with a conspecific temporal lobe epilepsy model mouse or inescapable foot-shock stress mouse models. After long-term housing, cage-mate was performed behavior tests and electrophysiological investigation. The conspecific cagemate showed increased anxiety and depression-like behavior. Furthermore, they showed significantly reduced social interaction with juvenile and anesthetized mouse. Behavioral dysfunction of cage-mate sustained four weeks after removing the mouse model. Interestingly, fluoxetine, serotonin selective reuptake inhibitor, hardly restored their behaviors. Our results suggest that a dweller whose cage-mate having brain disorder could develop abnormal behavior including reduced social and increased depression-like behavior. These findings may help to understand psychosocial or psychiatric symptoms frequently observed in at-risk nursing people or caregivers. PT669 Investigation of the antiinflammatory and gastric side effects of pregabalin Fatma Sultan Kilic1, Bilgin Kaygisiz1, Sule Aydin1, Hadi Karimkhani2, Cafer Yildirim1, Setenay Oner3 1 Eskisehir Osmangazi University Medical School, Department of Pharmacology 2 Eskisehir Osmangazi University Medical School, Department of Biochemistry 3 Eskisehir Osmangazi University Medical School, Department of Biostatistics Abstract Objectives: Nonsteroidal antiinflammatory drugs are used for the relief of inflammation, however gastrointestinal side effects restrict their clinical use. We aimed to investigate the antiinflammatory effects of pregabalin, a drug used in epilepsy, anxiety, neuropathic pain treatment, on carrageenaninduced paw edema and to evaluate its gastric side effects in Wistar rats. Methods: Pregabalin 30,50,100mg/kg; indomethacin 5mg/ kg(reference drug), vehicle(saline) were injected intraperitoneally before 100μl of 1% carrageenan administration into the right hind paws of the rats. Paw thickness was measured by a gauge calipers(Vernier Calipers) before (0th hour) and in every hour during 6 hours after induction of inflammation. Paw thickness of treated groups were compared with control group with One-way ANOVA. Also paw thickness in 0th and 6th hours were compared within each group with twoway ANOVA. Pregabalin was administered orally for 10 days to evaluate gastric side effect. At the end of 10 day treatment, rats were sacrificed, gastric tissues were removed out, mucus secretion was determined spectrophotometrically, ulcer index was scored from score 0:(no petechia) to score 3:(petechia>5mm). Results: There was no significant difference between 0th and 6th hours in paw thickness of all groups, except carrageenan group. Carrageenan significantly increased paw thickness in 6th hour compared to 0th hour. All doses of pregabalin and indomethacin significantly reduced paw thickness in 6th hour compared to carrageenan group. Pregabalin 50 and 100mg/kg similar to indomethacin significantly reduced mucus secretion and increased ulcer index compared to control while pregabalin 30mg/kg did not. Conclusion: All doses of pregabalin exerted antiinflammatory effects comparable to indomethacin, 50 and 100mg/kg pregabalin showed gastric side effects as reduced mucus secretion and ulcer formation similar to indomethacin and 30mg/kg pregabalin may be reasonable dose for antiinflammatory effect without showing gastric side effects. This study was supported by ‘Scientific Researchs Projects’ of Eskisehir Osmangazi University.

Effects of Simvastatin on Experimental Neuropathic Pain Model and the Role of Nitric Oxide

The aim of the present study was to evaluate putative antinociceptive effects of simvastatin and contribution of nitric oxide to experimental neuropathic pain model in rats. 48 Male, Sprague-Dawley rats (200-250g) were divided into seven groups. Simvastatin (10-20 mg/kg i.p.) was administered intraperitoneally for ten days to rats which were injured by main root ligation of sciatic nerve in chronic construction injury model. The antinociceptive activity of simvastatin was evaluated by using mechanical allodynia, thermal hyperalgesia and cold allodynia on the days of 0, 3, 7, 10. The same tests were performed to assess the role of nitric oxide, by using simvastatin 20mg/kg with 10mg/kg L-NAME or L-Arginine. Tramadol, used routinely in neuropathic pain treatment, was evaluated as a positive control. In all tests, hindpaw withdrawal thresholds and latencies were obtained for ligated, control and sham operated groups 30 minutes after drug or vehicle injections. Simvastatin (10-20 mg/kg) and tramadol 10 mg/kg groups significantly increased paw withdrawal latency on third day in mechanical allodynia test. Simvastatin 20mg/kg and tramadol groups significantly increased antinociceptive effect on tenth day. L-NAME+simvastatin 20mg/kg combination showed significant effect on the tenth day. L-Arginine+simvastatin 20mg/kg significantly decreased paw withdrawal threshold as compared to simvastatin (10-20 mg/kg) on the third day. There was no significant difference between groups in terms of thermal hyperalgesia. Simvastatin 20mg/kg significantly increased paw withdrawal latency on the tenth day as compared to control group in cold allodynia test. Simvastatin 20mg/kg significantly decreased the neuropathic pain in the present study. As a conclusion it seems that nitric oxide pathway may contribute to antinociceptive effect of simvastatin.