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336 REPEATED INTRACISTERNAL PRE084 INFUSION ENHANCES NEURONAL ACTIVITY IN TRIGEMINAL NUCLEUS CAUDALIS IN RAT
S102
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
333 RELATIONSHIP BETWEEN NOCICEPTIVE SENSITIVITY AND BODY DISSATISFACTION IN PATIENTS WITH SELF-INJURIOUS BEHAVIOR A. Yamamotova1 *, V. Kmoch2 , H. Papezova2 . 1 3rd Faculty of Medicine, Charles University, Dpt Physiology, Prague 2, Czech Republic; 2 Charles University in Prague, 1st Faculty of Medicine, Department of Psychiatry, Prague, Czech Republic Background: Self-injurious behavior (SIB) is parasuicidal activity leading to physical self-harm and damage of the body integrity without the conscious intention to die. Changed body image perception, pain perception and high rates of SIB have been described in eating-disordered patients. Methods: We analyzed relationship between body dissatisfaction and pain perception in 17 DSM-IV diagnosed patients with eating disorders with SIB and 15 patients without SIB. Patients were age, BMI, illness duration and diagnoses matched. The pain threshold latencies on radiant heat stimuli were measured using the Analgesia meter (IITC Life Science USA). Intensity of pain during the cold pressor test (CPT) at the time of hand removal from ice-water mixture was assessed by visual analogue scale. Body image perception and dissatisfaction were measured using software Anamorphic Micro. Results: Patients with SIB did not differ in thermal nociception from control patients; they tolerated CPT longer and assessed cold pain as less intensive than control patients. SIB patients were likely to report more dissociative experiences (Somatoform Dissociation Questionnaire) than control patients. In both groups, pain threshold latencies correlated positively with objective dissatisfaction with own body (Desired Size/True Image Size; in pixels). In SIB patients only, pain intensity of CPT correlated negatively with subjective dissatisfaction (Desired Size/Estimation Size). None of measured pain characteristics correlated with Body Image Perception (Estimation Size/True Image Size). Conclusions: In patient with SIB, contrary to patients with pain, nociceptive sensitivity is related more to body dissatisfaction than to body size perception. Supported by MSM 0021620816. 334 PRE- AND POST-SYNAPTIC 5-HT1A RECEPTORS MODULATE EXTRACELLULAR SIGNAL-REGULATED KINASES 1/2 PHOSPHORYLATION IN RAT BRAIN: ROLE OF THE MEK SIGNALLING PATHWAY J. Buritova *, G. Berrichon, D. Cussac. Pierre Fabre Research Center, Castres, France Background and Aims: 5-HT1A receptors are involved in control of pain states but few studies have explored the potential role of the Extracellular signal-Regulated Kinases 1/2 (ERK) signalling pathway along with the 5-HT1A receptor activation in rat brain. Using a quantitative Enzyme Linked-Immuno-Sorbent Assay (ELISA), we examine here the 5-HT1A receptor coupling to phospho (p)ERK levels in hippocampus, prefrontal cortex and hypothalamus. Methods: Rats were intraperitoneally injected with 5-HT1A agonists 8-OH-DPAT and its isomers (0.16–2.5 mg/kg), ERK kinase (MEK) inhibitor SL327 (25–100 mg/kg). SL327 (100 mg/kg) and 5-HT1A antagonist WAY100635 (0.63 mg/kg, subcutaneously or 32 mg in raphe nucleus) were injected 20–30 min before (+)8-OH-DPAT (2.5 mg/kg). In all studies, rats (n = 6) were decapitated 30 min after 5-HT1A agonist injection. Results: ELISA quantification revealed that (+/−)8-OH-DPAT dosedependently reduced hippocampal pERK as of 0.16 mg/kg although 4-fold higher dose (0.63) was necessary to stimulate pERK in prefrontal cortex and hypothalamus. First active dose was 0.63 mg/kg for (−)8-OH-DPAT and (+)8-OH-DPAT in all regions, except for (−)8-OH-DPAT in hippocampus where 2.5 mg/kg was necessary to achieve pERK inhibition. In all regions studied, SL327 dose-dependently reduced pERK by itself and dramatically reduced (+)8-OH-DPAT-induced pERK modulation. Systemic pre-
treatment with WAY100635 abolished (+)8-OH-DPAT-mediated pERK modulation in all regions. Furthermore, WAY100635 microinjection directly in raphe reduced (+)8-OH-DPAT-induced pERK inhibition in hippocampus, suggesting that pERK response in this post-synaptic area are controlled via pre-synaptic 5-HT1A receptor activation. Conclusions: pERK modulation in rat brain is mediated by preand post-synaptic 5-HT1A receptor activation and involves the MEK signalling pathway. 335 ANALGESIC EFFICACY IN RAT MODELS OF EXPERIMENTAL PAIN OF A NEW SELECTIVE SIGMA-1 RECEPTOR ANTAGONIST G. Gris1 *, A. Vidal1 , M. Fort1 , B. Aubel1 , L. Romero1 , A. Gonzalez ´ 1, E. Portillo-Salido1 , J.M. Baeyens2 , J.M. Vela1 , K. Deseure3 , D. Zamanillo1 . 1 Department of Pharmacology, Laboratorios ESTEVE, Barcelona, Spain; 2 Department of Pharmacology and Institute of Neuroscience, Faculty of Medicine, Universidad de Granada., Granada, Spain; 3 Laboratory of Anesthesiology, University of Antwerp, Antwerp, Belgium In previous studies using sigma-1 receptor (s1 R) knockout mice and pharmacological tools, we identified s1 R as a new potential target for the treatment of neuropathic pain based on its regulating effects on activity-induced sensitization in nociceptive pathways. Given the attractive therapeutic potential, we have developed a selective s1 R antagonist (S1RA) and we describe here its analgesic profile in different experimental models of acute and chronic pain in rats. S1RA was evaluated in the acute nociceptive pain model of tail-flick and it failed to exert a significant effect on response latencies when administered alone at active doses in other tests. However, S1RA potentiated morphine analgesia in the tail-flick test. S1RA dose-dependently potentiated the effect of subactive doses of morphine. Interestingly, the compound was active when administered alone in pain models involving sensitization and chronic pain. S1RA dose-dependently inhibited capsaicin-induced mechanical allodynia and formalin-induced pain. When evaluating inflammatory pain, S1RA reduced carrageenan-induced thermal hyperalgesia. Mechanical hypersensitivity was also reduced in a visceral pain model secondary to intracolonic TNBS administration. The compound was also active in reducing mechanical allodynia when administered acutely and chronically in two different models of neuropathic pain (streptozotocin-induced diabetic neuropathy and infraorbital nerve ligation). Altogether, these pharmacological results confirm the therapeutic potential of blocking s1 R as a new mechanism of action for the treatment of pain and identify S1RA as a novel analgesic compound. 336 REPEATED INTRACISTERNAL PRE084 INFUSION ENHANCES NEURONAL ACTIVITY IN TRIGEMINAL NUCLEUS CAUDALIS IN RAT Y.C. Jeong1 *, J.K. Kwon2 , Y.B. Kwon1 , K.W. Kim1 . 1 Department of Pharmacology, Institute for Medical Science, Chonbuk National University Medical School, Jeonju, South Korea; 2 Department of Laboratory Animal Medicine, College of Veterinary Medicine, Chonbuk National University, Jeonju, South Korea Intracranial headaches including migraine are generally accepted to be mediated by prolonged nociceptive activation of trigeminal nucleus caudalis (TNC) but the precise mechanisms are poorly understood. Our accumulative studies demonstrate that sigma-1 receptors (Sig-1R) facilitate nociceptive transmission in the spinal cord. From these findings, present study was further investigated whether activation of Sig-1R affects TNC neuronal activation as a key mechanism underlying the generation of headache. Rats were intracisternally infused with selective Sig-1R agonist PRE084 once or repeatedly for 3, 7 and 14 day. A single infusion of PRE084 dose-dependently increased Fos immunoreactive neurons (Fos-IR) in TNC with BD1047 (Sig-1R antagonist) reversed manner, but
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
the number of Fos-IR was lower than that of single capsaicin infusion as one of headache models. Chronic infusion of PRE084 over 7 day led to comparable number of Fos-IR in TNC with that of capsaicin single infusion. Consistently, the increase of face grooming/scratching behavior was evident from 7 day and peaked at 14 day after PRE084 infusion, which was co-related with the elevation of DFosB in TNC as a marker of sustained pain. Furthermore, PRE084 infusion for 14 days significantly increased protein kinase A and the phosphorylation of its downstream factors including NMDA receptor subunit 1, extracellular-signal regulated kinase and cAMP response element-binding protein in TNC. Thus, our findings indicated that the chronic activation of Sig-1R may evoke prolonged neuronal activation in trigeminovascular system relating to migraine. 337 CHOLINERGIC M2, BUT NOT M1, RECEPTOR IMMUNOREACTIVITY EXPRESSION DIMINISHES IN THE ANTERIOR CINGULATE CORTEX IN A NEUROPATHIC MODEL OF NOCICEPTION 1 J.M. Ortega-Legaspi1,2 *, M. Leon-Olea ´ , A´ı. Melo1,2 , P. Lamothe1,2 1 1,3 Molina , K. Simon-Arceo ´ , A. Lopez-Avila ´ , U. Coffeen1 , O. Jaimes1 , F. Pellicer1 . 1 Direcci´ on de Neurociencias. Instituto Nacional de Psiquiatr´ıa Ram´ on de la Fuente, M´exico D.F., Mexico; 2 Facultad de Medicina. Universidad Nacional Aut´ onoma de M´exico, M´exico, D.F., Mexico; 3 Departamento de Atenci´ on a la Salud. Univesidad Aut´ onoma Metropolitana-Xochimilco, M´exico, D.F., Mexico A cholinergic muscarinic blockade with scopolamine microinjected into the anterior cingulate cortex (ACC) previous to nociceptive stimulation impairs nociceptive related memory. The ACC presents cholinergic input and the expression of muscarinic receptors, with the M1 and M2 being the most abundant. In this study we aimed to determine if there were changes in the ACC regarding M1 and M2 receptor expression using immunofluorescence in rats under neuropathic nociception and also if this effect could be reverted by a muscarinic blockade with scopolamine. Neuropathic nociception: thermonociceptive stimulus in the right hind paw (immersion in water at 55ºC for 20 s.) followed 30 minutes later by a right sciatic denervation. Scopolamine: 10 mg/250 nl microinjected into the left ACC prior to the induction of neuropathic nociception. Control: No treatment. Autotomy behaviour was recorded daily in all groups and on day 8 the rats were perfused with 4% paraformaldehyde. Indirect immunofluorescence was performed on ACC slices (parasagital 40 mm) with either anti M1 or M2 goat IgG antibody. 40X photomicrographs were taken to obtain integrated optical density (IOD). Autotomy in the scopolamine group was significantly diminished as compared to the neuropathic nociception group. This group, for the M2 receptor, showed a diminished IOD vs. control and scopolamine. The M1 receptor was non different between groups. The M2 receptor diminishes as a result of neuropathic nociception. Also, a muscarinic system manipulation in the ACC modifies the acquisition of nociceptive related memory. A reduced effect of this inhibitory receptor induces nociceptive related memory. 338 PHARMACOLOGICAL AND GENETIC EVIDENCE SUPPORTING THE POTENTIAL USEFULNESS OF BLOCKING SIGMA-1 RECEPTORS FOR THE TREATMENT OF NEUROPATHIC PAIN 1 E. Portillo-Salido1 *, X. Nadal2 , R. Sanchez-Arroyos ´ , D. Zamanillo1 , 3 2 1 1 K. Deseure , R. Maldonado , J.M. Vela . Department of Pharmacology, Laboratorios ESTEVE, Barcelona, Spain; 2 Laboratory of Neuropharmacology, Facultat de Ci`encies de la Salut i de la Vida, Universitat Pompeu Fabra., Barcelona, Spain; 3 Laboratory of Anesthesiology, University of Antwerp, Antwerp, Belgium BD-1063 is a pharmacological tool used as an antagonist of sigma-1 receptor (s1 R). We used this tool combined with s1 R knockout mice
S103
to assess the involvement of s1 R in neuropathic pain. To better characterize the compound we first evaluated its affinity for a panel of 60 receptors, enzymes and ion channels. BD-1063 showed high affinity for s1 R (Ki = 12.3 nM), but significant affinity (Ki < 1 mM) was also found for s2 R (Ki = 498 nM), serotonin transporter (Ki = 396 nM) and H1R (Ki = 768 nM). BD-1063 was administered to wild-type and s1 R knockout mice exposed to partial sciatic nerve injury. A clear thermal hyperalgesia and allodynia to mechanical and cold stimuli was found in wild-type mice. BD-1063 exerted dose-dependent antihiperalgesic and antiallodynic effects in all behavioural tests in wild-type mice. According to previous results, s1 R knockout mice developed thermal hyperalgesia but not mechanical or cold allodynia after nerve injury, and BD-1063 was able to reverse nerve injury-induced thermal hyperalgesia in s1 R knockout mice, suggesting that mechanisms other than s1 R accounted for the antihyperalgesic effects elicited by BD-1063. The effect of BD1063 was also evaluated following chronic constriction of the rat’s infraorbital nerve. Unilateral ligation of the infraorbital nerve induced a robust mechanical allodynia that was dosedependently inhibited by BD-1063. This study indicates that s1 R is as a ‘druggable’ protein with potential therapeutic utility for the treatment of neuropathic pain. 339 INHIBITION OF MECHANICAL ALLODYNIA SECONDARY TO CAPSAICIN AND CFA INJECTION IN MICE BY A NEW SELECTIVE SIGMA-1 RECEPTOR ANTAGONIST 1 R. Sanchez-Arroyos ´ *, C. Segales ´ 1 , J.M. Vela1 , J.M. Baeyens2 , D. Zamanillo1 . 1 Department of Pharmacology, Laboratorios ESTEVE, Barcelona, Spain; 2 Department of Pharmacology and Institute of Neuroscience, Faculty of Medicine, Universidad de Granada, Granada, Spain Previous studies using sigma-1 receptor (s1 R) knockout mice identify s1 R as a constituent of the mechanisms modulating activity-induced sensitization in nociceptive pathways. Here we evaluated the effect of a new selective sigma-1 receptor (s1 R) antagonist (S1RA) on capsaicin- and complete Freund’s adjuvant (CFA)-induced mechanical allodynia. s1 R knockout mice were used to reinforce the role played by s1 Rs and to confirm the involvement of s1 Rs in the effects elicited by S1RA. Mechanical allodynia was quantified in wild-type and s1 R knockout mice by measuring the hindpaw withdrawal response to von Frey filament stimulation. It has been previously shown that s1 R is essential for capsaicininduced mechanical hypersensitivity. According to these results, intraplantar administration of capsaicin dose-dependently induced mechanical allodynia in the ipsilateral hindpaw of wild-type mice, but capsaicin-induced mechanical allodynia was absent in s1 R knockout mice. As confirmed by the pharmacological approach, S1RA showed a dose dependent antiallodynic effect after capsaicin administration. Mechanical allodynia was also assessed in the CFAinduced inflammatory pain model in mice on post-inoculation day 4. Wild-type and s1 R knockout mice showed no differences in the thresholds of the ipsilateral paw. Interestingly, S1RA produced a clear, dose-dependent antiallodynic effect in wild type but not in s1 R knockout mice, suggesting that S1RA was able to produce its antiallodynic effect through a s1 R-mediated mechanism. Our results underline the therapeutic potential of blocking s1 R for the treatment of pain and identify S1RA as a new analgesic compound with a new mechanism of action.
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
333 RELATIONSHIP BETWEEN NOCICEPTIVE SENSITIVITY AND BODY DISSATISFACTION IN PATIENTS WITH SELF-INJURIOUS BEHAVIOR A. Yamamotova1 *, V. Kmoch2 , H. Papezova2 . 1 3rd Faculty of Medicine, Charles University, Dpt Physiology, Prague 2, Czech Republic; 2 Charles University in Prague, 1st Faculty of Medicine, Department of Psychiatry, Prague, Czech Republic Background: Self-injurious behavior (SIB) is parasuicidal activity leading to physical self-harm and damage of the body integrity without the conscious intention to die. Changed body image perception, pain perception and high rates of SIB have been described in eating-disordered patients. Methods: We analyzed relationship between body dissatisfaction and pain perception in 17 DSM-IV diagnosed patients with eating disorders with SIB and 15 patients without SIB. Patients were age, BMI, illness duration and diagnoses matched. The pain threshold latencies on radiant heat stimuli were measured using the Analgesia meter (IITC Life Science USA). Intensity of pain during the cold pressor test (CPT) at the time of hand removal from ice-water mixture was assessed by visual analogue scale. Body image perception and dissatisfaction were measured using software Anamorphic Micro. Results: Patients with SIB did not differ in thermal nociception from control patients; they tolerated CPT longer and assessed cold pain as less intensive than control patients. SIB patients were likely to report more dissociative experiences (Somatoform Dissociation Questionnaire) than control patients. In both groups, pain threshold latencies correlated positively with objective dissatisfaction with own body (Desired Size/True Image Size; in pixels). In SIB patients only, pain intensity of CPT correlated negatively with subjective dissatisfaction (Desired Size/Estimation Size). None of measured pain characteristics correlated with Body Image Perception (Estimation Size/True Image Size). Conclusions: In patient with SIB, contrary to patients with pain, nociceptive sensitivity is related more to body dissatisfaction than to body size perception. Supported by MSM 0021620816. 334 PRE- AND POST-SYNAPTIC 5-HT1A RECEPTORS MODULATE EXTRACELLULAR SIGNAL-REGULATED KINASES 1/2 PHOSPHORYLATION IN RAT BRAIN: ROLE OF THE MEK SIGNALLING PATHWAY J. Buritova *, G. Berrichon, D. Cussac. Pierre Fabre Research Center, Castres, France Background and Aims: 5-HT1A receptors are involved in control of pain states but few studies have explored the potential role of the Extracellular signal-Regulated Kinases 1/2 (ERK) signalling pathway along with the 5-HT1A receptor activation in rat brain. Using a quantitative Enzyme Linked-Immuno-Sorbent Assay (ELISA), we examine here the 5-HT1A receptor coupling to phospho (p)ERK levels in hippocampus, prefrontal cortex and hypothalamus. Methods: Rats were intraperitoneally injected with 5-HT1A agonists 8-OH-DPAT and its isomers (0.16–2.5 mg/kg), ERK kinase (MEK) inhibitor SL327 (25–100 mg/kg). SL327 (100 mg/kg) and 5-HT1A antagonist WAY100635 (0.63 mg/kg, subcutaneously or 32 mg in raphe nucleus) were injected 20–30 min before (+)8-OH-DPAT (2.5 mg/kg). In all studies, rats (n = 6) were decapitated 30 min after 5-HT1A agonist injection. Results: ELISA quantification revealed that (+/−)8-OH-DPAT dosedependently reduced hippocampal pERK as of 0.16 mg/kg although 4-fold higher dose (0.63) was necessary to stimulate pERK in prefrontal cortex and hypothalamus. First active dose was 0.63 mg/kg for (−)8-OH-DPAT and (+)8-OH-DPAT in all regions, except for (−)8-OH-DPAT in hippocampus where 2.5 mg/kg was necessary to achieve pERK inhibition. In all regions studied, SL327 dose-dependently reduced pERK by itself and dramatically reduced (+)8-OH-DPAT-induced pERK modulation. Systemic pre-
treatment with WAY100635 abolished (+)8-OH-DPAT-mediated pERK modulation in all regions. Furthermore, WAY100635 microinjection directly in raphe reduced (+)8-OH-DPAT-induced pERK inhibition in hippocampus, suggesting that pERK response in this post-synaptic area are controlled via pre-synaptic 5-HT1A receptor activation. Conclusions: pERK modulation in rat brain is mediated by preand post-synaptic 5-HT1A receptor activation and involves the MEK signalling pathway. 335 ANALGESIC EFFICACY IN RAT MODELS OF EXPERIMENTAL PAIN OF A NEW SELECTIVE SIGMA-1 RECEPTOR ANTAGONIST G. Gris1 *, A. Vidal1 , M. Fort1 , B. Aubel1 , L. Romero1 , A. Gonzalez ´ 1, E. Portillo-Salido1 , J.M. Baeyens2 , J.M. Vela1 , K. Deseure3 , D. Zamanillo1 . 1 Department of Pharmacology, Laboratorios ESTEVE, Barcelona, Spain; 2 Department of Pharmacology and Institute of Neuroscience, Faculty of Medicine, Universidad de Granada., Granada, Spain; 3 Laboratory of Anesthesiology, University of Antwerp, Antwerp, Belgium In previous studies using sigma-1 receptor (s1 R) knockout mice and pharmacological tools, we identified s1 R as a new potential target for the treatment of neuropathic pain based on its regulating effects on activity-induced sensitization in nociceptive pathways. Given the attractive therapeutic potential, we have developed a selective s1 R antagonist (S1RA) and we describe here its analgesic profile in different experimental models of acute and chronic pain in rats. S1RA was evaluated in the acute nociceptive pain model of tail-flick and it failed to exert a significant effect on response latencies when administered alone at active doses in other tests. However, S1RA potentiated morphine analgesia in the tail-flick test. S1RA dose-dependently potentiated the effect of subactive doses of morphine. Interestingly, the compound was active when administered alone in pain models involving sensitization and chronic pain. S1RA dose-dependently inhibited capsaicin-induced mechanical allodynia and formalin-induced pain. When evaluating inflammatory pain, S1RA reduced carrageenan-induced thermal hyperalgesia. Mechanical hypersensitivity was also reduced in a visceral pain model secondary to intracolonic TNBS administration. The compound was also active in reducing mechanical allodynia when administered acutely and chronically in two different models of neuropathic pain (streptozotocin-induced diabetic neuropathy and infraorbital nerve ligation). Altogether, these pharmacological results confirm the therapeutic potential of blocking s1 R as a new mechanism of action for the treatment of pain and identify S1RA as a novel analgesic compound. 336 REPEATED INTRACISTERNAL PRE084 INFUSION ENHANCES NEURONAL ACTIVITY IN TRIGEMINAL NUCLEUS CAUDALIS IN RAT Y.C. Jeong1 *, J.K. Kwon2 , Y.B. Kwon1 , K.W. Kim1 . 1 Department of Pharmacology, Institute for Medical Science, Chonbuk National University Medical School, Jeonju, South Korea; 2 Department of Laboratory Animal Medicine, College of Veterinary Medicine, Chonbuk National University, Jeonju, South Korea Intracranial headaches including migraine are generally accepted to be mediated by prolonged nociceptive activation of trigeminal nucleus caudalis (TNC) but the precise mechanisms are poorly understood. Our accumulative studies demonstrate that sigma-1 receptors (Sig-1R) facilitate nociceptive transmission in the spinal cord. From these findings, present study was further investigated whether activation of Sig-1R affects TNC neuronal activation as a key mechanism underlying the generation of headache. Rats were intracisternally infused with selective Sig-1R agonist PRE084 once or repeatedly for 3, 7 and 14 day. A single infusion of PRE084 dose-dependently increased Fos immunoreactive neurons (Fos-IR) in TNC with BD1047 (Sig-1R antagonist) reversed manner, but
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
the number of Fos-IR was lower than that of single capsaicin infusion as one of headache models. Chronic infusion of PRE084 over 7 day led to comparable number of Fos-IR in TNC with that of capsaicin single infusion. Consistently, the increase of face grooming/scratching behavior was evident from 7 day and peaked at 14 day after PRE084 infusion, which was co-related with the elevation of DFosB in TNC as a marker of sustained pain. Furthermore, PRE084 infusion for 14 days significantly increased protein kinase A and the phosphorylation of its downstream factors including NMDA receptor subunit 1, extracellular-signal regulated kinase and cAMP response element-binding protein in TNC. Thus, our findings indicated that the chronic activation of Sig-1R may evoke prolonged neuronal activation in trigeminovascular system relating to migraine. 337 CHOLINERGIC M2, BUT NOT M1, RECEPTOR IMMUNOREACTIVITY EXPRESSION DIMINISHES IN THE ANTERIOR CINGULATE CORTEX IN A NEUROPATHIC MODEL OF NOCICEPTION 1 J.M. Ortega-Legaspi1,2 *, M. Leon-Olea ´ , A´ı. Melo1,2 , P. Lamothe1,2 1 1,3 Molina , K. Simon-Arceo ´ , A. Lopez-Avila ´ , U. Coffeen1 , O. Jaimes1 , F. Pellicer1 . 1 Direcci´ on de Neurociencias. Instituto Nacional de Psiquiatr´ıa Ram´ on de la Fuente, M´exico D.F., Mexico; 2 Facultad de Medicina. Universidad Nacional Aut´ onoma de M´exico, M´exico, D.F., Mexico; 3 Departamento de Atenci´ on a la Salud. Univesidad Aut´ onoma Metropolitana-Xochimilco, M´exico, D.F., Mexico A cholinergic muscarinic blockade with scopolamine microinjected into the anterior cingulate cortex (ACC) previous to nociceptive stimulation impairs nociceptive related memory. The ACC presents cholinergic input and the expression of muscarinic receptors, with the M1 and M2 being the most abundant. In this study we aimed to determine if there were changes in the ACC regarding M1 and M2 receptor expression using immunofluorescence in rats under neuropathic nociception and also if this effect could be reverted by a muscarinic blockade with scopolamine. Neuropathic nociception: thermonociceptive stimulus in the right hind paw (immersion in water at 55ºC for 20 s.) followed 30 minutes later by a right sciatic denervation. Scopolamine: 10 mg/250 nl microinjected into the left ACC prior to the induction of neuropathic nociception. Control: No treatment. Autotomy behaviour was recorded daily in all groups and on day 8 the rats were perfused with 4% paraformaldehyde. Indirect immunofluorescence was performed on ACC slices (parasagital 40 mm) with either anti M1 or M2 goat IgG antibody. 40X photomicrographs were taken to obtain integrated optical density (IOD). Autotomy in the scopolamine group was significantly diminished as compared to the neuropathic nociception group. This group, for the M2 receptor, showed a diminished IOD vs. control and scopolamine. The M1 receptor was non different between groups. The M2 receptor diminishes as a result of neuropathic nociception. Also, a muscarinic system manipulation in the ACC modifies the acquisition of nociceptive related memory. A reduced effect of this inhibitory receptor induces nociceptive related memory. 338 PHARMACOLOGICAL AND GENETIC EVIDENCE SUPPORTING THE POTENTIAL USEFULNESS OF BLOCKING SIGMA-1 RECEPTORS FOR THE TREATMENT OF NEUROPATHIC PAIN 1 E. Portillo-Salido1 *, X. Nadal2 , R. Sanchez-Arroyos ´ , D. Zamanillo1 , 3 2 1 1 K. Deseure , R. Maldonado , J.M. Vela . Department of Pharmacology, Laboratorios ESTEVE, Barcelona, Spain; 2 Laboratory of Neuropharmacology, Facultat de Ci`encies de la Salut i de la Vida, Universitat Pompeu Fabra., Barcelona, Spain; 3 Laboratory of Anesthesiology, University of Antwerp, Antwerp, Belgium BD-1063 is a pharmacological tool used as an antagonist of sigma-1 receptor (s1 R). We used this tool combined with s1 R knockout mice
S103
to assess the involvement of s1 R in neuropathic pain. To better characterize the compound we first evaluated its affinity for a panel of 60 receptors, enzymes and ion channels. BD-1063 showed high affinity for s1 R (Ki = 12.3 nM), but significant affinity (Ki < 1 mM) was also found for s2 R (Ki = 498 nM), serotonin transporter (Ki = 396 nM) and H1R (Ki = 768 nM). BD-1063 was administered to wild-type and s1 R knockout mice exposed to partial sciatic nerve injury. A clear thermal hyperalgesia and allodynia to mechanical and cold stimuli was found in wild-type mice. BD-1063 exerted dose-dependent antihiperalgesic and antiallodynic effects in all behavioural tests in wild-type mice. According to previous results, s1 R knockout mice developed thermal hyperalgesia but not mechanical or cold allodynia after nerve injury, and BD-1063 was able to reverse nerve injury-induced thermal hyperalgesia in s1 R knockout mice, suggesting that mechanisms other than s1 R accounted for the antihyperalgesic effects elicited by BD-1063. The effect of BD1063 was also evaluated following chronic constriction of the rat’s infraorbital nerve. Unilateral ligation of the infraorbital nerve induced a robust mechanical allodynia that was dosedependently inhibited by BD-1063. This study indicates that s1 R is as a ‘druggable’ protein with potential therapeutic utility for the treatment of neuropathic pain. 339 INHIBITION OF MECHANICAL ALLODYNIA SECONDARY TO CAPSAICIN AND CFA INJECTION IN MICE BY A NEW SELECTIVE SIGMA-1 RECEPTOR ANTAGONIST 1 R. Sanchez-Arroyos ´ *, C. Segales ´ 1 , J.M. Vela1 , J.M. Baeyens2 , D. Zamanillo1 . 1 Department of Pharmacology, Laboratorios ESTEVE, Barcelona, Spain; 2 Department of Pharmacology and Institute of Neuroscience, Faculty of Medicine, Universidad de Granada, Granada, Spain Previous studies using sigma-1 receptor (s1 R) knockout mice identify s1 R as a constituent of the mechanisms modulating activity-induced sensitization in nociceptive pathways. Here we evaluated the effect of a new selective sigma-1 receptor (s1 R) antagonist (S1RA) on capsaicin- and complete Freund’s adjuvant (CFA)-induced mechanical allodynia. s1 R knockout mice were used to reinforce the role played by s1 Rs and to confirm the involvement of s1 Rs in the effects elicited by S1RA. Mechanical allodynia was quantified in wild-type and s1 R knockout mice by measuring the hindpaw withdrawal response to von Frey filament stimulation. It has been previously shown that s1 R is essential for capsaicininduced mechanical hypersensitivity. According to these results, intraplantar administration of capsaicin dose-dependently induced mechanical allodynia in the ipsilateral hindpaw of wild-type mice, but capsaicin-induced mechanical allodynia was absent in s1 R knockout mice. As confirmed by the pharmacological approach, S1RA showed a dose dependent antiallodynic effect after capsaicin administration. Mechanical allodynia was also assessed in the CFAinduced inflammatory pain model in mice on post-inoculation day 4. Wild-type and s1 R knockout mice showed no differences in the thresholds of the ipsilateral paw. Interestingly, S1RA produced a clear, dose-dependent antiallodynic effect in wild type but not in s1 R knockout mice, suggesting that S1RA was able to produce its antiallodynic effect through a s1 R-mediated mechanism. Our results underline the therapeutic potential of blocking s1 R for the treatment of pain and identify S1RA as a new analgesic compound with a new mechanism of action.