TY - JOUR
T1 - Melatonin reduces formalin-induced nociception and tactile allodynia in diabetic rats
AU - Arreola-Espino, Rosaura
AU - Urquiza-Marín, Héctor
AU - Ambriz-Tututi, Mónica
AU - Araiza-Saldaña, Claudia Ivonne
AU - Caram-Salas, Nadia L.
AU - Rocha-González, Héctor I.
AU - Mixcoatl-Zecuatl, Teresa
AU - Granados-Soto, Vinicio
PY - 2007/12/22
Y1 - 2007/12/22
N2 - The purpose of this study was to assess the antinociceptive and antiallodynic effect of melatonin as well as its possible mechanism of action in diabetic rats. Streptozotocin (50 mg/kg) injection caused hyperglycemia within 1 week. Formalin-evoked flinching was increased in diabetic rats as compared to non-diabetic rats. Oral administration of melatonin (10-300 mg/kg) dose-dependently reduced flinching behavior in diabetic rats. In addition, K-185 (a melatonin MT2 receptor antagonist, 0.2-2 mg/kg, s.c.) completely blocked the melatonin-induced antinociception in diabetic rats, whereas that naltrexone (a non-selective opioid receptor antagonist, 1 mg/kg, s.c.) and naltrindole (a selective δ opioid receptor antagonist, 0.5 mg/kg, s.c.), but not 5′-guanidinonaltrindole (a selective κ opioid receptor antagonist, 1 mg/kg, s.c.), partially reduced the antinociceptive effect of melatonin. Given alone K-185, naltrexone, naltrindole or 5′-guanidinonaltrindole did not modify formalin-induced nociception in diabetic rats. Four to 8 weeks after diabetes induction, tactile allodynia was observed in the streptozotocin-injected rats. On this condition, oral administration of melatonin (75-300 mg/kg) dose-dependently reduced tactile allodynia in diabetic rats. Both antinociceptive and antiallodynic effects were not related to motor changes as melatonin did not modify number of falls in the rotarod test. Results indicate that melatonin is able to reduce formalin-induced nociception and tactile allodynia in streptozotocin-injected rats. In addition, data suggest that melatonin MT2 and δ opioid receptors may play an important role in these effects.
AB - The purpose of this study was to assess the antinociceptive and antiallodynic effect of melatonin as well as its possible mechanism of action in diabetic rats. Streptozotocin (50 mg/kg) injection caused hyperglycemia within 1 week. Formalin-evoked flinching was increased in diabetic rats as compared to non-diabetic rats. Oral administration of melatonin (10-300 mg/kg) dose-dependently reduced flinching behavior in diabetic rats. In addition, K-185 (a melatonin MT2 receptor antagonist, 0.2-2 mg/kg, s.c.) completely blocked the melatonin-induced antinociception in diabetic rats, whereas that naltrexone (a non-selective opioid receptor antagonist, 1 mg/kg, s.c.) and naltrindole (a selective δ opioid receptor antagonist, 0.5 mg/kg, s.c.), but not 5′-guanidinonaltrindole (a selective κ opioid receptor antagonist, 1 mg/kg, s.c.), partially reduced the antinociceptive effect of melatonin. Given alone K-185, naltrexone, naltrindole or 5′-guanidinonaltrindole did not modify formalin-induced nociception in diabetic rats. Four to 8 weeks after diabetes induction, tactile allodynia was observed in the streptozotocin-injected rats. On this condition, oral administration of melatonin (75-300 mg/kg) dose-dependently reduced tactile allodynia in diabetic rats. Both antinociceptive and antiallodynic effects were not related to motor changes as melatonin did not modify number of falls in the rotarod test. Results indicate that melatonin is able to reduce formalin-induced nociception and tactile allodynia in streptozotocin-injected rats. In addition, data suggest that melatonin MT2 and δ opioid receptors may play an important role in these effects.
KW - Diabetes
KW - Melatonin
KW - Melatonin MT receptor
KW - Naltrexone
KW - Naltrindole
KW - Tactile allodynia
UR - http://www.scopus.com/inward/record.url?scp=35448967487&partnerID=8YFLogxK
U2 - 10.1016/j.ejphar.2007.09.006
DO - 10.1016/j.ejphar.2007.09.006
M3 - Artículo
C2 - 17920585
SN - 0014-2999
VL - 577
SP - 203
EP - 210
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 1-3
ER -