Majallah-i Dānishgāh-i ̒Ulūm-i Pizishkī-i Bābul (Apr 1999)
The effect of different concentrations of Saccharin on Morphine analgesia in mice with Formalin test
Abstract
Objective: This study was done to investigate the relative role of sweetness and comparative effects of different taste sensation of non-caloric sweetener, saccharin, on pain and morphine antinociception by Formalin-test in mice. Methods: The Formalin-test was chosen because it measures the response to a long-lasting nociceptive stimulus and thus may closely resemble clinical pain. Findings: Twelve day pretreatment of animals with saccharin (0.04%, 0.08%, 0.16%) potentiated the low dose (1.5 mg/kg) of morphine-induced analgesia in early phase significantly but their effects diminished by increasing the concentration of morphine. Also in the early phase of the antinociception recording, all doses of saccharin antagonized the effect of morphine (3 mg/kg) dose-dependently and the effect of high doses of morphine (6-9 mg/kg) was antagonized by dose of saccharin (0.04%) but the effect of morphine (6 mg/kg) potentiated with high concentrations of saccharine (0.08% and 0.16%). All doses of saccharine decreased morphine analgesic effect at a dose of 9 mg/kg. Analgesic effects of low doses of morphine (1.5-3 mg/kg) were decreased by all doses of saccharine in late phase. Different concentrations of saccharin also affected the antagonistic effect of naloxone (0.4 mg/kg) on morphine-induced analgesia in both phases in Formalin-test. The high dose of saccharin (0.16%) potentiated the effect of naloxone in late phase. Conclusion: The obtained results support that hedonic is an important factor in morphine analgesia. Moreover, it seems important to consider sweet taste sensation. It is therefore inappropriate to use different concentrations of sweet saccharin solutions interchangeably.
