Ascorbic Acid inhibits development of tolerance and dependence to opiates in mice: possible glutamatergic or dopaminergic modulation

Abstract

In a recent study, it has been demonstrated that ascorbic acid possessed antidopaminergic activity and modulate the glutamatergic neurotransmission in mice. With this background, the present study was undertaken to study the effect of ascorbic acid on the development of tolerance and dependence to opiate and its mechanism of action. Male Swiss mice weighing 20-25 g were used in the present study. Mice were made physically dependent on opioid by the chronic administration of morphine (10 mg/kg, twice a day, for 9 days) intraperitoneally. Ascorbic acid, haloperidol (dopamine antagonist) or MK 801 (NMDA receptor antagonist) was administered daily for 9 d before challenging the animals with morphine. The development of tolerance was assessed by noting the tail-flick latency on day 1, 3, 9 and 10. On the 10(th) day after the measurement of tail-flick latency, animals were challenged with naloxone (2 mg/kg., i.p.) and incidence of escape jumps were recorded by placing the animals in 45 cm high plexiglass container. Ascorbic acid (400-1600 mg/kg) dose dependently inhibited development of tolerance and dependence to morphine as noted from tail-flick latency. When given along with MK 801 (0.01 mg/kg., i.p) or haloperidol (0.1 mg/kg i.p.), ascorbic acid (800 mg/kg., i.p.) potentiated the response of MK 801 or haloperidol. In conclusion, it is hypothesized that inhibition of development of tolerance and dependence to morphine by ascorbic acid appears to have two components, namely dopaminergic and glutamatergic.

Keywords: Ascorbic acid; dependence; dopamine; glutamate; tolerance.

Fig. 1

Ascorbic acid on the development of tolerance to the antinociceptive effect of morphine. Effect of chronic administration of morphine administration on antinociceptive response and various doses of ascorbic acid (400-1600 mg/kg) on the development of tolerance to the analgesic effect of morphine was assessed employing tail-flick method in mice. n = 5-9 for various treatment groups. ***p < 0.001 as compared to morphine treated group. [–●– saline; –◆– Ctrl (morphine); –▲– AA (400); –×– AA (800); –■– AA (1600)].

Fig. 2

Effect of MK 801 alone and in combination with ascorbic acid on morphine tolerance. Effect of low doses of MK 801 (0.01 mg/kg) alone and in combination with ascorbic acid (800 mg/kg) to the analgesic effect of morphine was assessed employing tail-flick method in mice. n = 5-9 for various treatment groups. ***p < 0.001 as compared to morphine treated group. [–●– saline; –◆– Ctrl (Morphine); –×– AA (800); –▲– MK 801 (0.01); –■– AA(800) + MK 801 (0.01)].

Fig. 3

Effect of haloperidol alone and in combination with ascorbic acid on morphine tolerance. Effect of haloperidol (0.1 mg/kg) alone and in combination with ascorbic acid (800 mg/kg) on the development of tolerance to the analgesic effect of morphine was assessed by employing tail-flick method in mice. n = 5-9 for various treatment groups. ***p < 0.001 as compared to morphine treated group. [–●–saline; –◆– Ctrl (Morphine); –×–AA (800); –▲– Hal (0.1); –■– AA (800) + Hal (0.1)].

Fig. 4

Effect of chronic treatment with ascorbic acid alone and in combination with haloperidol and MK 801 on analgesic response Per se effect of MK 801 (0.01 mg/kg) and haloperidol (0.1 mg/kg) alone or in combination with ascorbic acid (800 mg/kg) on analgesic response on different days. On 10^th day all the groups were challenged with respective treatment followed by morphine (10 mg/kg). (n = 5-9) for various treatment groups. [–●–saline; –◆– Ctrl (Morphine); –▲– AA (400); –×– AA (800); –■– AA (1600); –○– MK 801 (0.01); –△– AA (800) + MK 801; –□– Hal (0.1); –◊–AA (800) + Hal (0.1)].

Fig. 5

Effect of ascorbic acid alone or in combination with MK 801 and haloperidol on morphine withdrawal-induced jumps in mice. Effect of various doses of ascorbic acid (400-1600 mg/kg) and MK 801 (0.01 mg/kg) or haloperidol (0.1 mg/kg) alone or in combination with ascorbic acid (800 mg/kg) on naloxone-precipitated withdrawal jumps in morphine-dependent mice. (n = 5-9) for various treatment groups. ***p < 0.001 as compared to morphine treated group.